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13 June 1997

    Source: http://www.hnd.usace.army.mil/techinfo/cegssgml/16650.sec (SGML format)

    See Guide Specifications for Military Construction: http://jya.com/cegs.htm

    -------------------------------------------------------------------------------

      **************************************************************************
      DEPARTMENT OF THE ARMY                               CEGS-16650 (May 1996)
      U.S.  ARMY CORPS OF ENGINEERS                        _____________________
                                      GUIDE SPECIFICATION FOR MILITARY CONSTRUCTION
      **************************************************************************

                                   SECTION 16650
                           ELECTROMAGNETIC (EM) SHIELDING

                                       05/96

      **************************************************************************
                    NOTE:  This guide specification covers the
                    requirements for electromagnetic shielded
                    facilities.  This guide specification is to be
                    used in the preparation of project specifications in
                    accordance with ER 1110-345-720.
      **************************************************************************

    PART 1   GENERAL

      **************************************************************************
                    NOTE:  The following information will be shown on
                    the project drawings:

                    1.  Assembly details.

                    2.  Typical penetration details.

                    3.  Method of mounting shielded enclosure within
                    building.

                    4.  Shield penetration plan containing wall
                    elevations, floor and ceiling plans showing the
                    locations of all penetrations (to include all mech.,
                    electrical, fire protection, etc.) to the HEMP
                    shield.

                    5.  Location of mechanical and electrical equipment
                    within shielded enclosure.

                    6.  Detail equipment mounted or suspended from the
                    shielded ceiling.

                    7.  Shield penetration schedule to include:
                    a.  Location of the waveguide.
                    b.  Size of waveguide (dimensions).
                    c.  No. Of penetrations in the waveguide.
                    d.  Penetration designation of each penetration
                    in the waveguide (if more than one).
                    e.  Size of pipe for each penetration in the
                    waveguide.
                    f.  Type of pipe for each waveguide
                    penetration.
                    g.  Type of penetration.
                    h.  The detail/sheet no. of the waveguide
                    detail.
                    i.  Any remarks pertaining to the waveguide.

                    8.  Filter schedule to include:
                    a.  Location of filter.
                    b.  Type of filter (power or signal).
                    c.  No. Of filters in the filter enclosure.
                    d.  Electrical characteristics of the filter
                    (voltage, amperage, no. of poles, frequency).
                    e. Purpose of the filter.
                    f.  The detail/sheet no. Of the typical filter
                    detail.
                    g.  Any remarks pertaining to the filter.

                    9.  Typical filter details.

                    10.  Hardness critical items (HCI) should be
                    identified using the (HCI) symbol on project
                    drawings.

                    Refer to MIL-HDBK 419 for special grounding and
                    bonding requirements for EM shielded enclosures.
                    Refer to the U.S. Air Force Handbook for the Design
                    and Construction of HEMP/TEMPEST and Other Shields
                    in Facilities (March 1993).  This document can be
                    obtained from HQ AFIC/LEEE, San Antonio, Texas
                    78243-5001.  Also refer to AR 380-19.  MIL-HDBK 423
                    should be used for projects requiring HEMP
                    protection.  The designer should consult these
                    documents and other appropriate sources before
                    applying this guide specification to large-scale EM
                    shielded enclosures or to HEMP or TEMPEST projects.
                    The requirement for thermal expansion joints
                    inherent to large-scale enclosures is not addressed
                    in this guide specification.  The extent and
                    location of the work to be accomplished and wiring,
                    equipment, and accessories necessary for a complete
                    installation should be indicated on the project
                    drawings.  The Air Force contracts with an
                    independent testing laboratory to perform their
                    acceptance testing.  The test can consist of a SELDS
                    or equivalent test and H-field and plane wave CW
                    tests per MIL-STD 188 125 and/or IEEE STD 299.  See
                    the U.S. Air Force Handbook for the Design and
                    Construction of HEMP/TEMPEST and Other Shields in
                    Facilities for more details.  Methodology and
                    procedures for setting up equipment are contained in
                    MIL-HDBK-423.  Full MIL-STD 188 125 acceptance
                    testing (PCI tests as specified in appendix B)
                    should be avoided.  (Also see designer notes K and
                    U).  Although not addressed in this specification,
                    fiber optic cable has gained acceptance as an
                    effective method of transmitting data across the
                    boundary of shielded enclosures without filtering.
                    If fiber optic cable is used, describe the waveguide
                    penetration of the shield in detail.  Fiber optic
                    cable is specified in CEGS 16768, FIBER OPTICS DATA
                    TRANSMISSION SYSTEM.
      **************************************************************************

    1.1   REFERENCES

      **************************************************************************
                    NOTE:  Issue (date) of references included in
                    project specifications need not be more current than
                    provided by the latest change (Notice) to this guide
                    specification.
      **************************************************************************

      The publications listed below form a part of this specification to the
      extent referenced.  The publications are referred to in the text by basic
      designation only.

                AMERICAN HARDBOARD ASSOCIATION (AHA)

      AHA A135.4    (1995) Basic Hardboard

                AMERICAN INSTITUTE OF STEEL CONSTRUCTION (AISC)

      AISC-MO16    (1989) ASD Manual of Steel Construction

                AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM)

      ASTM A 36    (1994a) Carbon Structural Steel

      ASTM A 123    (1989a) Zinc (Hot Dip Galvanized)
        Coatings on Iron and Steel Products

      ASTM A 227    (1993) Steel Wire, Cold-Drawn for
        Mechanical Springs

      ASTM A 366    (1991; R 1993) Steel, Sheet, Carbon,
        Cold-Rolled, Commercial Quality

      ASTM A 526    (1990) Steel Sheet; Zinc-Coated
        (Galvanized) by the Hot-Dip Process,
        Commercial Quality

      ASTM A 568    (1993a) Steel, Sheet, Carbon, and
        High-Strength, Low-Alloy, Hot-Rolled and
        Cold-Rolled, General Requirements for

      ASTM A 569    (1991a; R 1993) Steel, Carbon (0.15
        Maximum, Percent), Hot-Rolled Sheet and Strip
        Commercial Quality

      ASTM A 611    (1994) Steel, Sheet, Carbon, Cold-Rolled,
        Structural Quality

      ASTM A 653    (1995) Steel Sheet, Zinc-Coated
        (Galvanized) or Zinc-Iron Alloy-Coated
        (Galvannealed) by the Hot-Dip Process

      ASTM B 194    (1995) Copper-Beryllium Alloy Plate,
        Sheet, Strip, and Rolled Bar

      ASTM B 545    (1992) Electrodeposited Coatings of Tin

      ASTM B 633    (1985; R 1994) Electrodeposited Coatings
        of Zinc on Iron and Steel

      ASTM E 84    (1995a) Surface Burning Characteristics
        of Building Materials

      ASTM E 90    (1990) Laboratory Measurement of Airborne
        Sound Transmission Loss of Building
        Partitions

                AMERICAN WELDING SOCIETY (AWS)

      AWS A5.18    (1993) Carbon Steel Electrodes and Rods
        for Gas Shielded Arc Welding

      AWS BRH    (1991) Brazing Handbook

      AWS D1.1    (1994) Structural Welding Code - Steel

      AWS D1.3    (1989) Structural Welding Code - Sheet
        Steel

      AWS D9.1    (1990) Sheet Metal Welding Code

                DEPARTMENT OF COMMERCE (DOC)

      DOC PS 1    (1983) Construction and Industrial
        Plywood

                INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS (IEEE)

      IEEE C62.11    (1993) IEEE Standard Metal-Oxide Surge
        Arresters for AC Power Circuits

      IEEE C62.33    (1982; R 1994) Varistor Surge-Protective
        Devices

      IEEE C62.41    (1991) Surge Voltages in Low-Voltage AC
        Power Circuits

      IEEE STD 142    (1991) IEEE Recommended Practice for
        Grounding of Industrial and Commercial Power
        Systems

      IEEE STD 299    (1991) IEEE Standard Method of Measuring
        the Effectiveness of the Electromagnetic
        Shielding Enclosures

                MILITARY HANDBOOKS (MIL-HDBK)

      MIL-HDBK 419    (Rev A) Grounding, Bonding, and Shielding
        for Electronic Equipments and Facilities

                MILITARY STANDARDS (MIL-STD)

      MIL-STD 188 124    (Rev B) Grounding, Bonding and Shielding
        (Metric)

      MIL-STD 188 125    (Rev A) High-Altitude Electromagnetic
        Pulse (HEMP) Protection for Ground-Based C4I
        Facilities Performing Critical, Time-Urgent
        Missions, Vol. I Fixed Facilities (Metric)

      MIL-STD 220    (Rev A; Notice 1 & 2) Method of
        Insertion-Loss Measurement

                NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION (NEMA)

      NEMA ICS 2    (1993) Industrial Control Devices,
        Controllers and Assemblies

      NEMA ICS 6    (1993) Enclosures for Industrial Controls
        and Systems

      NEMA MG 1    (1993; Rev 1-1993; Rev 2-1995) Motors and
        Generators

                NATIONAL FIRE PROTECTION ASSOCIATION (NFPA)

      NFPA 70    (1996) National Electrical Code

      NFPA 77    (1993) Static Electricity

      NFPA 80    (1995) Fire Doors and Windows

      NFPA 80A    (1993) Protection of Buildings from
        Exterior Fire Exposures

      NFPA 101    (1994) Safety to Life from Fire in
        Buildings and Structures

      NFPA 780    (1992) Installation of Lightning
        Protection Systems

                UNDERWRITERS LABORATORIES (UL)

      UL 486A    (1991; Rev Oct 1991) Wire Connectors and
        Soldering Lugs for Use with Copper Conductors

      UL 1283    (1993; Rev Aug 1993) Electromagnetic
        Interference Filters

      UL 1449    (1985; Errata Apr 1986) Transient Voltage
        Surge Suppressors

    1.2   SYSTEM DESCRIPTION

      **************************************************************************
                    NOTE:  Projects involving military communications
                    equipment must be designed to incorporate the
                    applicable requirements of MIL-STD 188 124, which
                    will be provided in the ELECTRICAL WORK, INTERIOR
                    specification.
      **************************************************************************

      The shielded facility shall meet or exceed minimum attenuation decibel (dB)
      levels specified herein.  The EM shielding system shall include, but is not
      limited to, the following:

      a.  The [welded steel] [bolted] EM shield.

      b.  EM shielded doors for access into the facility.

      c.  Electrical and electronic penetrations of the shield.

      d.  EM filter/surge arrester assemblies, including their EM enclosures.

      e.  EM shielded pull boxes and junction boxes.

      f.  EM shielded conduit runs.

      g.  Special protective measures for mission-essential equipment outside
      the EM shield.

      h.  Structural penetrations.

      i.  Mechanical and utility penetrations (such as air ducts, gas, and
      water).

      j.  Instrumentation and control.

      k.  Equipment door/access panels.

    1.3   SUPERVISION

      Work performed under this section shall be supervised and inspected by the
      shielding specialist.  Materials and equipment shall be approved and
      verified by the shielding specialist before being submitted to the
      Contracting Officer for approval.  The submittal shall be date stamped and
      signed by the shielding specialist.  The shielding specialist shall be
      responsible for coordinating the required shielding work with the work of
      all other trades that will interface or affect the shielding work in any
      way.  The contractor shall provide sufficient supervisory and/or quality
      control personnel on site to supervise the installation crew and to conduct
      in-progress quality assurance tests.

    1.4   SUBMITTALS

      **************************************************************************
                    NOTE:  Submittals must be limited to those necessary
                    for adequate quality control.  The importance of an
                    item in the project should be one of the primary
                    factors in determining if a submittal for the item
                    should be required.

                    Indicate submittal classification in the blank space
                    using "GA" when the submittal requires Government
                    approval or "FIO" when the submittal is for
                    information only.
      **************************************************************************

      Government approval is required for submittals with a "GA" designation;
      submittals having an "FIO" designation are for information only.  The
      following shall be submitted in accordance with Section 01300 SUBMITTAL
      PROCEDURES

      SD-01 Data

      Electromagnetic Shielding System; GA.

      Manufacturer's data, catalog cuts, and printed documentation regarding the
      work.

      SD-04 Drawings

      Electromagnetic Shielding System; GA.

      Installation details showing location, number, and method of penetrating
      the shielding material.  Fabrication details for penetrations of the
      shielding material and the complete EM shielded enclosure to include doors
      and filters.  Drawings shall show erection details and sequence of erection
      and shall clearly indicate the methods necessary to ensure shield integrity
      under all columns and other structural members.

      SD-06 Instructions

      EM Shielding System Installation Plan; GA.  Quality Control
      Plan; GA.

      Instruction for the shielding installation provided by the shielding
      installers.

      SD-07 Schedules

      EM Door; GA.  EM Filter Assemblies; GA.  EM Penetrations
      Schedule; GA.

      Filter schedule shall include voltage, amperage, enclosure type (low, high,
      band pass), system, location, cut-off frequency, band pass frequencies, and
      electrical surge arresters (ESA).

      SD-08 Statements

      EM Shielding Specialist Qualifications; GA.  EM Shielding Testing
      Specialist Qualifications; GA.  EM Shielding Installers
      Qualifications; GA.  Welders Qualifications; GA.

      SD-09 Reports

      Enclosure Sound Transmission Testing; GA.  Swinging Door Static
      Load Test; GA.  Swinging Door Sag Test; GA.  Door Closure
      Test; GA.  Door Handle-Pull Test; GA.  Door EM Shielding
      Effectiveness Test; GA.  Door Sound Transmission Test; GA.
      Filter Current Overload Capability Test; GA.  Filter Insertion
      Loss Test; GA.  Filter Operating Temperature and Temperature Rise
      Test; GA.  Filter Voltage Drop Test; GA.  Filter Dielectric
      Withstand Voltage Test; GA.  Filter Insulation Resistance Test;
      GA.  Filter Enclosure Shielding Effectiveness Test; GA.
      Filter Terminals Test; GA.  Filter Harmonic Distortion Test;
      GA.  Filter Reactive Shunt Current Test; GA.  ESA Breakdown
      Voltage Test; GA.  ESA Impulse Sparkover Voltage Test; GA.
      ESA Clamping Voltage Test; GA.  ESA Extinguishing Test; GA.
      ESA Extreme Duty Discharge Test; GA.  ESA Surge Life Test;
      GA.  EM Waveguide Assembly Testing; GA.  EM Cabinet and Pull
      Box Shielding Effectiveness Testing; GA.  Field Testing Reports;
      GA.

      SD-13 Certificates

      Welders Certification; GA.

      SD-18 Records

      Field Testing Results; FIO.

      SD-19 Operation and Maintenance Manuals

      EM Shielding System; FIO.

    1.5   QUALIFICATIONS

    1.5.1   Shielding Specialists, Installers and Testing Specialists

      The name and background qualifications of individuals who will be
      responsible for installation, supervision, and testing of the shielding
      systems on this project shall be provided.  Shielding and testing
      specialist credentials shall include a bachelor's degree in science or
      engineering and post-degree training and experience with EM shielding.

    1.5.1.1   Testing Experience

      The testing specialist shall have experience during the previous 5 years in
      shielded enclosure leak detection system (SELDS), IEEE STD 299, and
      other methods of shielded enclosure testing.

    1.5.1.2   Work Experience

      The EM shielded system shall be provided by an experienced firm or
      individual that has been regularly and successfully engaged in the
      installation, supervision, and/or testing of equivalent EM shielded systems
      for at least the previous 5 years.  The principal work of this firm or
      individual shall be the satisfactory installation and construction of EM
      shielded protection systems.  Such experience shall include achieving
      specified requirements for shielded system attenuation and maintainability
      of attenuation levels on work performed.

    1.5.1.3   Project Experience

      A project experience list shall be furnished on projects of similar scope
      which have been completed during the previous 5 years.  Project completion
      dates and the name and telephone number of the user and/or owner of each
      project shall be included.  Project experience for installers shall
      indicate the installation responsibilities, performance, materials, and
      methods used.  Project experience for the shielding specialist shall
      indicate the responsibilities performed.  Project experience for the
      testing specialist shall indicate the test methods performed.

    1.5.2   Qualifications of Welders

      Welding shall be performed by certified welders.  The Contractor shall
      provide the names of the welders to be employed and certification that each
      welder has passed qualification tests within the last 2 years in the
      processes specified in AWS D1.1, AWS D9.1, and as required by the
      Contracting Officer.

    1.6   FILTER AND ELECTRICAL WORK REQUIREMENTS

      Filter and electrical work shall comply with NFPA 70, UL 486A, and
      UL 1283.  The label and listing of the Underwriters Laboratories or
      other nationally recognized testing laboratory shall be acceptable evidence
      that the material or equipment conforms to the applicable standards of that
      agency.  In lieu of the label or listing, a certificate may be furnished
      from an acceptable testing organization adequately equipped and competent
      to perform such services.  The certificate shall state that the items have
      been tested and that they conform to the specified standard.

    1.7   FIELD EXAMPLES

      **************************************************************************
                    NOTE:  Requests for field examples and mock-ups
                    usually add cost to the project.  Samples should
                    only be required for special applications and should
                    be limited to scaled-down items.  For example, the
                    designer may ask for a welded floor/wall corner
                    section.  Do not normally ask for samples of filters
                    and full-size waveguide vents.
      **************************************************************************

      Field examples shall be provided for the following:  [shielding sheet
      installation,] [shielding fastening,] [doors,] [[30] [100] [_____] ampere
      power filter,] [communication filter,] [waveguide,] [penetration,] and
      [_____].

    1.8   PREINSTALLATION CONFERENCE

      A preinstallation conference for EM shielding shall be held with the
      Contractor and installers working in, on, or near the EM shield.
      Coordination requirements shall be discussed and instructions shall be
      stated to ensure the integrity of the EM shield.

    1.9   DELIVERY AND STORAGE

      Equipment shall be delivered and stored with protection from excessive
      humidity and temperature variation, dirt, and other contaminants.

    1.10  FIELD MEASUREMENTS

      The Contractor shall become familiar with details of the work, verify
      dimensions in the field, and shall advise the Contracting Officer of any
      discrepancy before performing the work.

    1.11   PROJECT/SITE REQUIREMENTS

      Welding of EM shielding material and sheet steel shall be performed at an
      ambient temperature of [10 degrees C] [50 degrees F] minimum to
      [32 degrees C] [90 degrees F] maximum.  Shielding shall not be
      installed until the building has been weather enclosed.  Sheet steel
      welding shall not be performed in direct sunlight.

    1.12   EXTRA MATERIALS

      [One] [_____] extra EM power filter[s] and [one] [_____] extra
      communications filter[s] of each different type furnished on the project
      shall be furnished as a spare.

    1.13   SOURCE QUALITY CONTROL

      Factory tests shall be performed as described herein.  The Contracting
      Officer reserves the right to witness the specified factory tests.  The
      Contracting Officer shall be notified at least 30 days before factory tests
      are scheduled to be performed.  Test data shall include a detailed
      description of the test instrumentation and equipment, including
      calibration dates, a detailed description of the test procedure, and the
      recorded test data.

    1.14   OPERATING AND MAINTENANCE MANUAL

      The manual shall address all components and aspects of the EM shielding and
      shall include, but not be limited to, the following:

      a.  A complete set of assembly drawings to include penetration
      locations and installation details.

      b.  The construction specification on EM shielding.

      c.  Shield penetration schedule.

      d.  Power/signal filter schedule.

      e.  Test plan.

      f.  The prepared preventive maintenance instructions for periodic
      inspection, testing and servicing, lubrication, alignment, calibration, and
      adjustment events normally encountered.  Complex preventive maintenance
      events shall be extracted from or shall refer to detailed vendor or
      manufacturer data.  This information shall be derived from an evaluation of
      engineering data considering local environmental conditions, manufacturer's
      recommendations, estimated operating life for the specific application and
      use of the equipment, and types of job skills available at the operating
      site.

      g.  Spare parts data approved and verified by the shielding specialist
      prior to submission.  The data shall include a complete list of recommended
      parts and supplies with current unit prices and source of supply.

      h.  Provide a list of hardness critical items (HCI) requiring periodic
      inspection to maintain EM shield integrity.  Hardness critical items are
      those components and/or construction features which singularly and
      collectively provide specific levels of HEMP protection, such as the EM
      shield, surge arresters, EM shielded doors, shield welding, electrical
      filters, honeycomb waveguides, and waveguides-below-cutoff.

    PART 2   PRODUCTS

    2.1   GENERAL

    2.1.1   Standard Products

      Materials and equipment shall be the standard products of a manufacturer
      regularly engaged in the manufacture of such products and shall essentially
      duplicate items that have been in satisfactory use for at least 2 years
      prior to bid opening.  Equipment shall be supported by a service
      organization that is, in the opinion of the Contracting Officer, reasonably
      convenient to the site.

    2.1.2   Nameplates

      Each major item of equipment shall have the manufacturer's name, address,
      type or style, model or serial number, and catalog number on a plate
      secured to the item of equipment.

    2.1.3   Special Tools

      One set of special tools, calibration devices, and instruments required for
      operation, calibration, and maintenance of the equipment shall be provided
      as follows:

      [SELDS Test Set]

      [_____]

    2.1.4   Testability

      Equipment and materials of the EM shielding shall be designed and built to
      facilitate testing and maintenance.

    2.2   EM SHIELDING EFFECTIVENESS

      **************************************************************************
                    NOTE:  The designer will consider the shield as
                    early in the design as possible while the geometry
                    of the shielded enclosure can be located to utilize
                    components inherent in the structure.  Failure to
                    consider the shield configuration first in the
                    design will increase design costs, cause problems in
                    its incorporation into the structure, and lose
                    installation simplicity.  The EM shielded enclosure
                    design should be coordinated by the structural,
                    mechanical, and electrical engineers and architect.
                    The structural and shielding systems should drive
                    each other on large projects.  Multi-story shielded
                    enclosures require continuous connections of
                    shielding steel interconnected to the structural
                    steel.  In these cases, the shielding wall layout
                    should coincide with the structural steel beam
                    layout.  The shield within an exterior building
                    concept must employ a design which allows for
                    settling, seismic motion, and differential thermal
                    expansion between the steel and concrete of the
                    building and the steel of the EM shielding.
      **************************************************************************

      The EM shielded enclosure complete with all filters, doors, and/or
      waveguides shall have the following minimum EM shielding effectiveness
      attenuation.  Minimum magnetic field attenuation shall be [20 dB] [_____]
      at 14 kHz increasing linearly to [50 dB] [100 dB] at [200 kHz] [1 MHz]
      [_____].  Minimum electric field and plane wave attenuation shall be [50
      dB] [100 dB] [_____] from 14 kHz to [1 GHz] [10 GHz] [_____].

    2.3   EM SHIELDING ENCLOSURE REQUIREMENTS (WELDED CONSTRUCTION)

      **************************************************************************
                    NOTE:  For the EM shielding enclosure, choose either
                    welded or bolted construction.  The unused method
                    should be deleted from the project specification.
                    Welded construction will usually consist of
                    continuous 1.897 mm (14 gauge) thick steel plate and
                    angles to form the enclosure.  Thicker material may
                    be used if it is more cost-effective or required for
                    structural reasons.  Welded construction is used
                    when a shielded facility requires a long
                    maintainable service life of high-level protection,
                    100 dB attenuation, or HEMP protection, 100 dB.
                    Bolted construction is associated with a lower level
                    (50 dB) of maintained shielding effectiveness.
                    Bolted construction will usually consist of modular
                    panels bolted together with metal strips or
                    channels.  Panels are commonly plywood with steel
                    sheets laminated to one or both sides.  Bolted
                    construction is used when a shielded facility's
                    service life is short, 10 years or less, or the
                    system is required to be demountable for change of
                    location.  This system requires more maintenance
                    than a welded system and requires access to the
                    panels.  The EM shield layout may restrict
                    attenuation testing of the enclosure.  It is
                    desirable for large facilities to place the shield
                    at least 1 meter (3.3 feet) inside the exterior
                    walls, although cost and construction restrict this
                    consideration.  The floor shielding can be tested by
                    SELDS test but not by IEEE STD 299 if it is on
                    grade.  The facility layout must be carefully
                    planned to allow for testing and shield maintenance.
      **************************************************************************

    2.3.1   Welded Shielding Enclosure

      **************************************************************************
                    NOTE:  Shielding steel thickness should not be based
                    solely on the minimum thickness required for
                    HEMP/TEMPEST attenuation.  Thicker steel may be
                    necessary because of structural factors and heat
                    deformation or burn-through from seam welding.
      **************************************************************************

      The intent of this section and the drawings is to provide a complete metal
      enclosure including floor, walls, ceiling, doors, penetrations, welds, and
      the embedded structural members to form a continuous EM shielded enclosure.
      Shielding sheets and closures shall be [1.897] [_____] mm [14]
      [_____] gauge thick cold-rolled steel for walls and ceiling conforming to
      ASTM A 366 and [3.416] [_____] mm [10] [_____] gauge thick
      hot-rolled steel for floors conforming to ASTM A 568 or ASTM A 569.
      Steel plates, channels, or angles of minimum 6 mm 1/4 inch thick
      shall be used to reinforce shield sheets for attachments of ducts,
      waveguides, conduit, pipes, and other penetrating items.  Furring channels
      used to attach shielding sheets to walls or floors shall be the minimum
      gauge of the shielding steel.  The shielding sheet steel gauge may be
      thicker at the Contractor's option to reduce labor and welding effort only
      if structurally tolerable with the existing design.  Steel shall be free of
      oil, dents, rust, and defects.

    2.3.2   Metal Members

      Structural steel shapes, plates, and miscellaneous metal shall conform to
      ASTM A 36.  Furring channels shall conform to ASTM A 611.

    2.3.3   Steel and Welding Material

      Welding materials shall comply with the applicable requirements of AWS
      D1.1 and AWS D9.1.  Steel and welding material shall conform to
      AISC-MO16.  Welding electrodes shall conform to AWS D1.1 for metal
      inert gas (MIG) welding method.  Weld filler metal shall conform to AWS
      A5.18.

    2.3.4   Fasteners

      Self-tapping screws shall not be used for attachment of shielding.
      Power-actuated drive pins shall be zinc-coated steel, Type I, pin size No.
      4 to secure steel sheets to concrete surfaces and to light gauge furring
      channels.  The drive pins shall conform to ASTM A 227 Class 1 for
      materials and ASTM B 633 for plating.

    2.3.5   Miscellaneous Materials and Parts

      Miscellaneous bolts and anchors, supports, braces, and connections
      necessary to complete the miscellaneous metal work shall be provided.  The
      necessary lugs, rebars, and brackets shall be provided to assemble work.
      Holes for bolts and screws shall be drilled or punched.  Poor matching of
      holes will be cause for rejection.  Thickness of metal and details of
      assembly and supports shall provide ample strength and stiffness.  The
      materials shall be galvanically similar.

    2.3.6   Penetrations

      **************************************************************************
                    NOTE:  Configure the facility to minimize the number
                    of metallic structural elements required to
                    penetrate the barrier.
      **************************************************************************

      Penetrations of the shield, including bolts or fasteners, shall be sealed
      with puddle welds or full circumferential EM welds.  Structural
      penetrations including beams, columns, and other metallic structural
      elements shall be provided with continuously welded or brazed seams and
      joints between the penetrating element and the shield.  Nonmetallic
      structural elements shall not penetrate the electromagnetic barrier.

    2.3.7  Penetration Plates (Welded Construction)

      The penetration plate shall be the central location for treatment of
      penetrations.  The panel shall be constructed of 6 mm 1/4 inch
      thick ASTM A 36 steel plate welded to the shield.  Waveguide, conduit,
      and piping penetrations shall be circumferentially welded at the point of
      penetration to the inner surface of the penetration plate.  Penetration
      plates shall extend at least 150 mm 6 inches beyond all
      penetrations.

    2.3.8   Floor Finish

      **************************************************************************
                    NOTE:  Indicate or specify whether other flooring is
                    to be provided or higher floor loads are required.
                    This is most critical when raised floors are
                    specified.  Allowances must be made for elevated
                    door thresholds.  Specify special requirements for
                    laboratory loads or seismic loading in this
                    paragraph.  If concrete floor wearing slabs are
                    specified, they should be thick enough to hold
                    anchor bolts for equipment, supports, and interior
                    partitions.  Concrete wearing slabs may be provided
                    in most applications with a minimum thickness of 100
                    mm (4 inches).  The Air Force is opposed to placing
                    concrete wearing slabs over shielding steel because
                    of problems with testing and repair.  Placing
                    concrete over floor shielding requires a waiver from
                    HQ AFCESA/ENE.

                    Indicate or specify whether other flooring is to be
                    provided or higher floor loads are required.  This
                    is most critical when raised floors are specified.
                    Allowances must be made for elevated door
                    thresholds.  Specify special requirements for
                    laboratory loads or seismic loading in this
                    paragraph.  If concrete floor wearing slabs are
                    specified, they should be thick enough to hold
                    anchor bolts for equipment, supports, and interior
                    partitions.  Concrete wearing slabs may be provided
                    in most applications with a minimum thickness of 100
                    mm (4 inches).  The Air Force is opposed to placing
                    concrete wearing slabs over shielding steel because
                    of problems with testing and repair.  Placing
                    concrete over floor shielding requires a waiver from
                    HQ AFCESA/ENE.
      **************************************************************************  *

      Floor EM shielding shall be covered by a reinforced cast-in-place concrete
      slab [100] [_____] mm [4] [_____] inches thick.

    2.4   EM SHIELDING ENCLOSURE REQUIREMENTS (BOLTED CONSTRUCTION)

      **************************************************************************
                    NOTE:  For the EM shielding enclosure, choose either
                    welded or bolted construction.  The unused method
                    should be deleted from the project specification.
                    Welded construction will usually consist of
                    continuous 1.897 mm (14 gauge) thick steel plate and
                    angles to form the enclosure.  Thicker material may
                    be used if it is more cost-effective or required for
                    structural reasons.  Welded construction is used
                    when a shielded facility requires a long
                    maintainable service life of high-level protection,
                    100 dB attenuation, or HEMP protection, 100 dB.
                    Bolted construction is associated with a lower level
                    (50 dB) of maintained shielding effectiveness.
                    Bolted construction will usually consist of modular
                    panels bolted together with metal strips or
                    channels.  Panels are commonly plywood with steel
                    sheets laminated to one or both sides.  Bolted
                    construction is used when a shielded facility's
                    service life is short, 10 years or less, or the
                    system is required to be demountable for change of
                    location.  This system requires more maintenance
                    than a welded system and requires access to the
                    panels.  The EM shield layout may restrict
                    attenuation testing of the enclosure.  It is
                    desirable for large facilities to place the shield
                    at least 1 meter (3.3 feet) inside the exterior
                    walls, although cost and construction restrict this
                    consideration.  The floor shielding can be tested by
                    SELDS test but not by IEEE STD 299 if it is on
                    grade.  The facility layout must be carefully
                    planned to allow for testing and shield maintenance.
      **************************************************************************

    2.4.1   Panel Construction

      Flat steel sheets shall be laminated to each side of a 20 mm 3/4
      inch thick structural core of either plywood or hardboard.  Panels shall
      have a flame spread rating of less than 25 when tested according to ASTM
      E 84.  Flat steel shall conform to ASTM A 653 and ASTM A 526 with
      G-60 coating, minimum 0.5512 mm 26 gauge thick, zinc-coated
      phosphatized.  Plywood shall conform to DOC PS 1 for exterior, sound
      grade hardwood, Type I.  Hardboard shall conform to AHA A135.4, Class
      4, SIS, for standard type hardboard.  Adhesive for laminating steel sheets
      to structural core shall be a waterproof type which maintains a permanent
      bond for the lifetime of the enclosure.

    2.4.2   Framing

      Panels shall be joined and supported by specially designed framing members
      that clamp the edges of the panels and provide continuous, uniform, and
      constant pressure for contact to connect the shielding elements of the
      panels.  The walls shall be self supporting from floor to ceiling with no
      bracing.  Deflection of walls under a static load of 335 N 75
      pounds applied normally to the wall surface at any point along the
      framing members shall not exceed 1/250 of the span between supports.
      [Ceilings shall be self-supporting from wall to wall.] [Ceilings shall be
      supported by adjustable, nonconducting, isolated hangers from the
      structural ceiling above.]  Ceilings shall be designed to have a deflection
      under total weight, including ceiling finish, of not more than 1/270 of the
      span.  A one-piece factory pre-welded corner section or trihedral corner
      framed with a brass machine cast corner cap assembly consisting of inner
      and outer parts shall be provided at all corner intersections of walls and
      floor or ceiling.  The modular enclosure shall be designed for ease of
      erection, disassembly, and reassembly.

    2.4.3   Channel

      The framing-joining system members shall consist of 3 mm 1/8 inch
      thick zinc-plated steel channels having a minimum 16 mm 5/8 inch
      overlap along each side of the contacting surface.  Screw fasteners shall
      be spaced at 75 or 100 mm 3 or 4 inch intervals.  Screw fasteners
      shall be either zinc-or cadmium-plated steel, minimum size 6 mm 1/4
      inch - 20 with a pan or flat Phillips head.  Fasteners shall be
      heat-treated and hardened with a minimum tensile strength of 931 MPa.
      135,000 psi.

    2.4.4   Sound Transmission Class (STC)

      Enclosure panels shall have an STC of [30] [_____] dB minimum when tested
      according to ASTM E 90.

    2.4.5   Penetration Plates (Bolted Construction)

      Plates shall be a minimum 3 mm 1/8 inch thick ASTM A 36 steel
      plate, sized [450] [_____] mm [18] [_____] inches by [450]
      [_____] mm [18] [_____] inches and shall have a 6 mm 1/4 inch
      thick extruded brass frame for mounting to the shielded enclosure wall
      panel.  Penetration plates shall extend at least 150 mm 6 inches
      beyond all penetrations.

    2.5   EM SHIELDED DOORS

      **************************************************************************
                    NOTE:  Edit these paragraphs depending on type of
                    door used on project.
      **************************************************************************

    2.5.1   General

      Material in shielded doors and frames shall be steel conforming to ASTM A
      36, ASTM A 366 or ASTM A 568, and ASTM A 569 and shall be
      stretcher-leveled and installed free of mill scale.  Metal shall be thicker
      where indicated or required for its use and purpose.  Metal thresholds of
      the type for proper shielding at the floor shall be provided.  Fire rated
      shielded doors and assemblies shall meet NFPA 80 and NFPA 80A
      requirements and shall bear the identifying label of a nationally
      recognized testing agency qualified to perform certification programs.  The
      EM shielded doors shall be provided by a single supplier who has been
      regularly engaged in the manufacture of these items for at least the
      previous 5 years.  The assemblies shall be supplied complete with a rigid
      structural frame, hinges, latches, and parts necessary for operation.  The
      products supplied shall duplicate assemblies that have been in satisfactory
      use for at least 2 years.  The door frame shall be steel suitable for
      [welding] [bolting] to the surrounding structure and shield.  The EM
      filters, EM waveguide penetrations for door systems, and miscellaneous
      material shall be provided for a complete system.  The enclosure door shall
      be nonsagging and nonwarping.  The EM shielded door shall provide a
      shielding effectiveness of [10 dB] [20 dB] greater than the minimum EM
      shielding effectiveness requirements.  The door shall have a clear opening
      [as shown on the drawings] [of [915] [_____] mm [36] [_____] inches
      wide and [2135] [_____] mm [84] [_____] inches high].  The door and
      frame assembly shall have a sound rating of STC [30] [_____] minimum.
      Testing shall be performed in accordance with ASTM E 90.

    2.5.1.1   Door Latch

      The door latch shall be lever controlled with roller cam action requiring
      not more than 67 N 15 pounds of operating force on the lever handle
      for both opening and closing.  The door shall be equipped with a latching
      mechanism having a minimum of three latching points that provides proper
      compressive force for the EM seal.  The mechanism shall be operable from
      both sides of the door and shall have permanently lubricated ball or thrust
      bearings as required at points of pivot and rotation.

    2.5.1.2   Hinges

      Doors shall be equipped with a minimum of three well-balanced adjustable
      ball-bearing or adjustable radial thrust bearing hinges suitable for equal
      weight distribution of the shielded doors.  Hinges shall allow adjustment
      in two directions.  Force necessary to move the doors shall not exceed 22
      N. 5 pounds.

    2.5.1.3   Threshold Protectors

      Threshold protectors shall be furnished for each EM shielded door.
      Protectors shall consist of portable ramps that protect the threshold when
      equipment carts or other wheeled vehicles are used to move heavy items
      across the threshold.  The ramps may be asymmetrical to account for
      different floor elevations on each side, but the slope of the ramp shall
      not exceed 4:1 on either side.  Ramps shall be designed to support a
      [227] [_____] kg [500] [_____] pound vertical force applied to a
      75 by 13 mm 3 by 1/2 inch area for a personnel door, and a [907]
      [_____] kg [2,000] [_____] pound vertical force applied to a 75 by
      13 mm 3 by 1/2 inch area for an equipment double leaf door.  The
      force shall be applied to the contact area between the threshold and the
      door.  Mounting brackets, convenient to the entry, shall be provided to
      store the ramp when not in use.

    2.5.1.4   Frequency of Operation

      With proper maintenance, door assemblies shall function properly through
      100,000 cycles and 15-year service life minimum without the shielding
      effectiveness decreasing below the overall shield required attenuation.

    2.5.1.5   Electric Interlocking Devices

      Electric interlocking devices shall be provided for vestibules equipped
      with shielded doors at each end.  Electric interlocking devices shall be
      provided so that shielded doors at the ends of the vestibule cannot be
      opened at the same time during normal operation.  A manual override shall
      be provided to allow emergency egress, and an audible alarm shall be
      provided to indicate that doors at each end of the vestibule are open.  The
      alarm will continue to sound while both doors are open.  The Contractor
      shall provide a low-voltage piezoelectric-type alarm, in a tamperproof
      enclosure, at a location shown on the project drawings or as directed by
      the Contracting Officer's representative.  The sound intensity shall be
      45 dBA minimum at 3.05 m. 10 feet.  Lights shall be provided on the
      side of each door outside the vestibule to indicate that the other door is
      open.  Interlock systems may be integrated into a cypher lock system.  The
      interlock system shall be powered by an uninterruptible power source and
      shall be fail-safe in an unlocked condition in the event of a power
      failure.

    2.5.1.6   Electric Connectivity

      Electric connectivity for sensors, alarms, and electric interlocking
      devices shall be installed in accordance with the door manufacturer's
      instructions, the approved drawings, and Section 16415 ELECTRICAL WORK,
      INTERIOR.

    2.5.1.7  Threshold Alarm

      A press-at-any-point ribbon switch shall be applied to the threshold.  The
      switch shall enunciate an alarm whenever pressure is applied to the
      threshold of the EM shielded door.

    2.5.1.8   Hold Open and Stop Device

      Each EM shielded door leaf shall be provided with a hold open and stop
      device permanently attached to the door leaf.  Shielded doors shall have a
      fastener plate welded onto the door.  The device shall not interfere with
      the finger stock.  No drilling or tapping of the shielded door will be
      allowed.

    2.5.1.9   Emergency Exit Hardware

      Emergency exit EM shielded doors shall be equipped with single motion
      egress hardware.  The force required to latch and unlatch emergency exit
      hardware on EM shielded doors shall meet life safety code NFPA 101.
      Field alterations or modifications to panic hardware will not be allowed.

    2.5.1.10   Finish

      EM shielded doors shall be factory prime painted with zinc chromate primer.
      Doors may be factory finish painted or galvanized.  The Contractor shall
      touch up any damaged finish.

    2.5.1.11   Spare Parts

      The Contractor shall furnish one set of finger stock and EM gaskets (if
      used) for each hinged EM shielded door provided.  In addition, one set of
      manufacturer recommended and Contracting Officer approved spare parts for
      EM shielded doors of each style installed shall be provided.

    2.5.1.12   Tools

      The Contractor shall furnish one full set of tools that are required to
      maintain the doors and are not typically available from tool vendors.  The
      Contractor shall furnish environmentally safe lubricants, cleaning
      solvents, or coatings in sufficient quantities to last for [6] [_____]
      months.

    2.5.1.13   Maintenance Supplies and Procedures

      Maintenance supplies sufficient for a [3] [_____] year period or [50,000]
      [_____] open-close cycles, whichever is greater, shall be provided for each
      EM shielded door.  The maintenance instructions required to maintain the
      door through the cycle count shall be prominently displayed nearby.

    2.5.1.14   Door Counter

      A door operation counter shall be provided on the enclosure interior.

    2.5.1.15   Additional Hardware

      **************************************************************************
                    NOTE:  Alarms would normally be specified in Section
                    16725 INTRUSION DETECTION SYSTEM.  Hardware will be
                    specified in the hardware section.
      **************************************************************************

      See door schedule on drawings and Section 08700 BUILDER'S HARDWARE,
      for additional hardware requirements.  Fire rating and STC sound ratings
      shall be as required by the door finish schedule on the drawings or in the
      specifications.

    2.5.2   Latching Type Doors

      **************************************************************************
                    NOTE:  The knife edge shall be made of stainless
                    steel 430 series if it will be exposed to moist air
                    containing salt (near the sea coast) or in an
                    uncontrolled or corrosive environment.
      **************************************************************************

      Doors shall be [steel] [laminated] type.  [Steel doors shall be a minimum
      of 3.416 mm 10 gauge thick steel sheet electrically and
      mechanically joined by welded steel frames overlapping joints with
      continuous EM welds.] [Laminated type shall be the same construction as
      enclosure panels, except the steel faces shall be electrically and
      mechanically joined by channels or overlapping seams, both of which shall
      be continuously seam welded or soldered along all joined surfaces.]  The
      closure seal shall utilize an extruded brass channel containing a recess
      into which [two] [_____] sets of [beryllium copper condition HT in
      accordance with ASTM B 194] [stainless steel 430 (magnetic type)
      series] contact fingers and a closed cell foam rubber air seal are fitted
      and can be easily removed and replaced without the use of special tools and
      without the application of solders.  The door shall mate to the frame in a
      manner that allows the insertion of a brass knife edge between the two rows
      of the radio frequency finger stock, to obtain optimum conductivity and
      electromagnetic shielding.  High-temperature silver solder shall be used to
      attach the brass knife edge components to the door panels and the frame.
      The fingers that form a contact between the door and its frame shall be
      protected from damage due to physical contact and shall be concealed within
      the door and frame assembly.

    2.5.3   Pneumatic Sealing Doors

      Pneumatic sealing mechanisms shall achieve EM shielding by using pressure
      to force the door panel against the frame surface.  Contact areas of door
      and frame shall be a peripheral strip not less than 75 mm 3 inches
      wide completely around the door with a tinned or highly conductive
      noncorrosive surface.  After the door is in a closed position, the
      pneumatic sealing mechanism shall exert pressure in not more than 10
      seconds.  The sealing mechanism release shall be actuated in not more than
      5 seconds.  Manual [override] [operation] shall not exceed a maximum of
      [155] [_____] N [35] [_____] pounds  When the door is sealed, the
      attenuation around the edges shall meet the EM shielding effectiveness
      requirements of this specification.  Swinging doors shall have a threshold
      of zinc-plated steel, not less than 9.5 mm 3/8 inch thick.  The
      door shall be provided with a pneumatic system that maintains a nominal
      sealing pressure of [240] [_____] kPa. [35] [_____] psi.  A label
      shall be attached to pneumatic doors warning against painting of the mating
      surfaces.

    2.5.3.1   Door and Enclosure Design

      Doors shall be designed for long life and reliability without the use of EM
      gaskets, EM finger stock, or other sealing devices other than the direct
      metal-to-metal contact specified.  The EM sealing device shall be fail-safe
      upon loss of air pressure and shall readily allow manual opening of the
      door.  For either normal or fail-safe operation, the maximum time to reach
      the open position shall be no more than 7 seconds.  The enclosure design
      shall include provision for removing the door for routine maintenance
      without disturbing its alignment and EM sealing properties.

    2.5.3.2   Control Panel

      The inside and outside of the shielded enclosure shall contain a control
      panel including the necessary opening and closing pneumatic valves.  The
      outside control panel shall also have a pressure regulator and filter.  The
      door air supply shall be capable of quick opening from inside the enclosure
      to allow escape when opening pneumatic valves fail or malfunction.

    2.5.3.3   Air System for Pneumatic Sealing

      A complete air system including compressor, filter alarm, tank, lines, air
      filter, dryer, air control valves, and controls shall be provided.  Air
      tank capacity shall be sized so that the air volume and pressure are
      sufficient to operate the door through ten complete cycles after the loss
      of normal power.

    2.5.4   Magnetic Sealed Door Type

      An EM seal shall be formed by a solid metal-to-metal contact around the
      periphery of the door frame.  The materials at the contact area shall be
      compatible and corrosion resistant.  The contact force for the door EM seal
      shall be provided by electromagnets.  When the electromagnet is energized,
      the door leaf shall be pulled in to ensure a solid and continuous contact
      with the door frame.  When the electromagnet is de-energized, the door leaf
      shall be free to swing.  The EM shielded doors may use electromagnets or a
      combination of permanent magnets and electromagnets.

    2.5.5   Sliding Type Door

      A sliding shielded door shall be of the size and operating direction
      indicated.  Clear openings indicated on the drawings shall not require
      dismantling of any part of the door.  The door shall be manually operable
      from either side, inside or outside, with a maximum pull (force) of 155
      N 35 pounds to set the shielded door in motion.  Shielded door face
      panels and frames shall be constructed of reinforced steel suitable for
      achieving the specified attenuation.  Frames shall be constructed of steel
      shapes welded together to form a true rectangular opening.  In the sealed
      position, the shielded doors shall provide the minimum shielding
      effectiveness specified without any derating.  The doors shall be designed
      for long life and reliability and shall not use EM gaskets, EM finger
      stocks, or other sealing devices other than the specified direct
      metal-to-metal contact.  A label shall be attached to sliding doors warning
      against painting of the mating surfaces.

    2.5.6   Power Operators

      Power operators shall be [pneumatic] [electric] type conforming to NFPA
      80 and the requirements specified herein.  Readily adjustable limit
      switches shall be provided to automatically stop the door in its full open
      or closed position.  All operating devices shall be suitable for the
      hazardous class, division, and group defined in NFPA 70.

    2.5.6.1   Pneumatic Operators

      **************************************************************************
                    NOTE:  Designer will coordinate with the drawings to
                    ensure compressed air is available at door
                    locations.
      **************************************************************************

      Pneumatic operators shall be heavy-duty industrial type designed to operate
      the door at not less than 0.2 m/s 2/3 fps or more than 0.3 m/s
      1 fps with air pressure of [_____] kPa. [_____] psi.  A
      pressure regulator shall be provided if the operator is not compatible with
      available air pressure.  Dryer, filter, and filter alarm shall be provided.
      Pneumatic piping shall be provided up to the connection with building
      compressed air, but not more than 6 m 20 feet from door jambs.
      Operators shall have provisions for immediate emergency manual operation of
      the door in case of failure.  The operator shall open, close, start, and
      stop the door smoothly.  Control shall be [electrical, conforming to NEMA
      ICS 2 and NEMA ICS 6; enclosures shall be Type 12 (industrial use),
      Type 7 or 9 in hazardous locations, or as otherwise indicated] [pneumatic]
      [with] [pushbutton wall switches] [ceiling pull switches] [rollover floor
      treadle] [as indicated].

    2.5.6.2   Electric Operators

      Electric operators shall be heavy-duty industrial type designed to operate
      the door at not less than 0.2 m/s 2/3 fps or more than 0.3 m/s.
      1 fps.  Electrical controls shall be [pushbutton wall switches]
      [ceiling pull switches] [rollover floor treadle] [as indicated].  Electric
      power operators shall be complete with an electric motor, brackets,
      controls, limit switches, magnetic reversing starter, and other accessories
      necessary.  The operator shall be designed so that the motor may be removed
      without disturbing the limit switch timing and without affecting the
      emergency operator.  The power operator shall be provided with a slipping
      clutch coupling to prevent stalling of the motor.  Operators shall have
      provisions for immediate emergency manual operation of the door in case of
      electrical failure.  Where control voltages differ from motor voltage, a
      control voltage transformer shall be provided inside as part of the
      starter.  Control voltage shall be 120 volts or less.

      a.  Motors.  Drive motors shall conform to NEMA MG 1, shall be
      high-starting torque reversible type, and shall be of sufficient output to
      move the door in either direction from any position at the required speed
      without exceeding the rated capacity.  Motors shall be suitable for
      operation on [[120] [208] [277] [480] volts, 60 Hz] [[220] [240] [380]
      volts, 50 Hz], [single] [three] phase, and shall be suitable for
      across-the-line starting.  Motors shall be designed to operate at full
      capacity over a supply voltage variation of plus or minus 10 percent of the
      motor voltage rating.

      b.  Controls.  Each door motor shall have an enclosed reversing
      across-the-line type magnetic starter with thermal overload protection,
      limit switches, and remote control switches.  The control equipment shall
      conform to NEMA ICS 2; enclosures shall conform to NEMA ICS 6, and
      shall be Type 12 (industrial use), Type 7 or 9 in hazardous locations, or
      as otherwise indicated.  Each wall control station shall be of the
      three-button type, with the controls marked and color coded:  OPEN - white;
      CLOSE - green; and STOP - red.  When the door is in motion and the stop
      control is pressed, the door shall stop instantly and remain in the stop
      position.  From the stop position, the door shall be operable in either
      direction by the open or close controls.  Controls shall be of the
      full-guarded type to prevent accidental operation.

    2.5.6.3   Leading Edge Safety Shutdown

      Leading edges of the door with operators shall have a safety shutdown
      switch strip the entire length of the leading edge.  The safety strip shall
      be press-at-any-point ribbon switches.  Activation of the strip shall shut
      down the operator and release the door with reset required to continue door
      operation.

    2.5.7   EM Shielded Door Factory Test

      **************************************************************************
                    NOTE:  When specifying nonlatching doors, delete
                    door static load and sag tests and cycle test for
                    door latches.  Retain cycle test for door hinges.
      **************************************************************************

      Test data shall be provided on at least one shielded door of each type
      provided for the facility to verify that the EM shielded doors of the
      design supplied have been factory tested for compliance with this
      specification.  Test doors shall not be furnished on the project.  Test
      data reports shall be submitted in accordance with paragraph SUBMITTALS.

    2.5.7.1   Swinging Door Static Load Test

      The door shall be mounted and latched to its frame, then set down in a
      horizontal position such that it will open downward with only the frame
      rigidly and continuously supported from the bottom.  A load of 195
      kg/psm 40 lb/psf shall be applied uniformly over the entire surface
      of the door for at least 10 minutes.  The door will not be acceptable if
      this load causes breakage, failure, or permanent deformation which causes
      the clearance between door leaf and stops to vary more than 1.6 mm
      1/16 in from the original dimension.

    2.5.7.2   Swinging Door Sag Test

      The door and its frame shall be installed normally and opened 90 degrees.
      Two 45 kg 100 pound weights, one on each side of the door, shall be
      suspended from the door within 130 mm 5 in of the outer edge for at
      least 10 minutes.  The door will not be acceptable if this test causes
      breakage, failure, or permanent deformation which causes the clearance
      between the door leaf and door frame to vary more than 1.6 mm 1/16
      in from the original dimension.

    2.5.7.3   Door Closure Test

      Each door design shall be operated 100,000 complete open-close cycles.  The
      door will not be acceptable if the closure test causes any breakage,
      failure, or permanent deformation which causes the clearance between the
      door and door frame to vary more than 1.6 mm 1/16 in from the
      original dimension.

    2.5.7.4   Handle-Pull Test

      The door shall be mounted and latched to its frame.  The handle shall have
      a force of 1100 N 250 pounds applied outward (normal to the surface
      of the door) at a point within 50 mm 2 in of the end of the handle.
      The door will not be acceptable if this test causes any breakage, failure,
      or permanent deformation exceeding 3 mm. 1/8 inch.

    2.5.7.5   Door Electromagnetic Shielding Test

      The EM shielded door shall be factory tested in accordance with the
      requirements of this specification both before and after the mechanical
      tests described above.

    2.6   ELECTROMAGNETIC FILTERS

      **************************************************************************
                    NOTE:  All EM filters for power and signal lines
                    should be scheduled on the drawings.

                    This guide specification covers electromagnetic
                    filters for 50, 60, and 400 Hz power lines and
                    signal lines for GENERAL USE ONLY.  This
                    specification is NOT applicable for filters to be
                    used with a specific individual item of electronic
                    equipment.  Filters for use with specific individual
                    items of equipment must be scheduled on the drawings
                    showing voltage, current, insertion loss, passband,
                    frequency, baud rate, and cutoff frequency.
      **************************************************************************

      A filter shall be provided for each power, data, and signal line
      penetrating the enclosure.  These lines shall include, but are not limited
      to, power lines, lines to dummy loads, alarm circuits, lighting circuits,
      and signal lines such as telephone lines, antenna lines, HVAC control, and
      fire alarm.  Filters [and ESAs] shall be enclosed in metallic cases which
      shall protect the filter elements from moisture and mechanical damage.  All
      external bonding or grounding surfaces shall be free from all insulating
      protective finishes.  All exposed metallic surfaces shall be suitably
      protected against corrosion by plating, lead-alloy coating, or other means.
      The finish shall provide good electrical contact when used on a terminal or
      as a conductor, shall have uniform texture and appearance, shall be
      adherent, and shall be free from blisters, pinholes and other defects.  The
      filter [and ESA] assemblies shall also meet the requirements of UL
      1283.  Insertion loss in the stop band between the load side of the
      filter and the power supply side shall be not less than the EM shielding
      attenuation specified herein.  The filter used for 400 Hz shall be provided
      with power factor correcting coil to limit the reactive current to 10
      percent maximum of the full load current rating.  Each filter unit shall be
      capable of being mounted individually and shall include one filter for each
      phase conductor of the power line and the neutral conductor.  The signal
      filters shall include one filter for each conductor.

    2.6.1  Enclosure

      **************************************************************************
                    NOTE:  The intent of this paragraph is to preserve
                    the integrity of the filter and to shield the input
                    and output circuits from each other.  Usually, this
                    is accomplished by mounting the filters in an
                    EM-modified NEMA Type 1 enclosure with separate
                    compartments for the input and the output terminals.
                    If a weatherproof or hazardous area type enclosure
                    is needed, it must be specified.
      **************************************************************************

      Filter units shall be mounted in an EM modified NEMA Type [1] [_____]
      enclosure in accordance with NEMA ICS 6 and meet the requirements of
      UL 1283.  Enclosures shall be made of corrosion resistant steel of
      1.9837 mm 14 gauge minimum thickness with welded seams and
      galvanized bulkhead cover plates.  The enclosure nonconductive surfaces
      shall be finished with a corrosion-inhibiting primer and two coats of baked
      or finish enamel.  The input compartment shall house the individual line
      filters and the input terminals of the filters and mounting for the surge
      arrestor.  Live parts shall be spaced in accordance with NFPA 70.
      Filter leads shall be copper.  Filter enclosures shall be shielding
      effectiveness tested in accordance with IEEE STD 299 and Table I of
      this specification.  [Test leads and coaxial connectors through the
      enclosure shall be provided for HEMP testing.] [The imbedded configuration
      shall be used for filter enclosures as required by MIL-STD 188 125.]

    2.6.1.1   Filter Unit Mounting

      Each filter unit shall be mounted individually in an enclosure containing
      one filter for each penetrating conductor.  One end of the individual
      filter case shall be attached to the rf barrier plate between the two
      compartments to provide and rf tight seal between the rf barrier plate and
      the filter case.  The terminals of the filters shall project through
      openings in the rf barrier plate into the inner terminal compartment.  The
      case of each filter shall be attached to both the enclosure and to the
      barrier plate to prevent undue stress being applied to the rf seal between
      the filter case and the rf barrier plate.  Individual filters shall be
      removable from the enclosure.  Like filters shall be interchangeable.

    2.6.1.2   Conduit Connections to Enclosures

      The load terminal and input compartments shall have no knockouts, and each
      compartment shall have weldable threaded conduit hubs.  The hubs shall be
      circumferentially EM welded in place and shall be sized and located as
      required for the conduits indicated.

    2.6.1.3   Access Openings and Cover Plates

      Enclosures shall have separate clear front access cover plates on terminal
      and power input compartments.  Access cover plates shall be hinged with EM
      gaskets and 75 mm 3 inch maximum bolt spacing.  The design shall
      include thick cover plates and folded enclosure edges to prevent enclosure
      deformation, bolt spacers to prevent uneven gasket compression, and gasket
      mounting to facilitate replacement.  All gasket contact areas shall be
      tin-plated using the electrodeposited type I method in accordance with
      ASTM B 545.  Nuts and bolts shall be permanently fastened to the
      enclosure by welding or captive attachments.

    2.6.1.4   Operating Temperature

      The filter and ESA assembly shall be rated for continuous operation, with
      filters at rated voltage and full-load currents, in ambient temperatures
      from minus 55 to plus 65 degrees C (measured outside the EM filter
      enclosure).  Filter components shall be suitable for continuous full load
      operation at a temperature from minus 55 to plus 85 degrees C.

    2.6.1.5   Short Circuit Withstand

      Filters shall be labeled and built to have standard short circuit withstand
      ratings in accordance with UL 1283.  The minimum ratings shall be as
      follows:

                                    FILTER RATED           SHORT CIRCUIT FULL LOAD
                                  CURRENT, RMS AMPERE          AMPERES SYMMETRICAL

                   0-100                    10,000
                 101-400                    14,000

    2.6.1.6   Filter Connections

      Individual filters shall have prewired standoffs and solderless lugs.  The
      lugs shall be of the hexagonal head bolt or screw type and shall conform to
      UL 486A.  Live parts shall be spaced in accordance with NFPA 70.

    2.6.2   Internal Encapsulated Filters (Filter Units)

      **************************************************************************
                    NOTE:  There are two kinds of power filters,
                    commonly known as "W" and "X" series.  The "W"
                    series filters are designed to achieve rated
                    insertion loss under load when tested in accordance
                    with MIL-STD 220, which only requires testing under
                    load conditions from 100 kHz to 20 MHz.  The "X"
                    series device data sheets will contain the phrase
                    "tested using extended range buffer networks" and
                    will satisfy the stated performance under full load
                    at frequencies below 100 kHz.  The "X" series
                    filters will also be tested in accordance with
                    MIL-STD 220.  The "X" series filters can also be
                    differentiated from "W" devices by the fact that
                    they are usually two to three times greater in
                    weight.

                    Fire alarm, signal, energy monitoring and control
                    system, telephone, and control lines require filters
                    that pass a specific frequency, voltage, and number
                    of conductors.  Fire alarm circuits with ground
                    fault indicators will show a ground fault when
                    connected through a filter and should be avoided.  A
                    fiber optic connection through the shield is
                    recommended.  Conductors penetrating the shield
                    perimeter shall be kept to a minimum.  Systems
                    penetrating the shield will have special
                    requirements in their specifications for
                    compatibility between system signal and control
                    circuits and the EM filters.
      **************************************************************************

    2.6.2.1   Filter Construction

      Individual filters shall be heavy-duty type sealed in a steel case.  After
      the filter is filled with an impregnating or encapsulating compound, the
      seams shall be welded.  When a solid potting compound is used to fill the
      filter, the filters may be mechanically secured and sealed with solder.
      Hermetically sealed impregnated capacitors shall be used, or the complete
      filter assembly shall be vacuum impregnated.  Individual filter cases shall
      be fabricated of not less than 2 mm 14 gauge thick steel and
      finished with a corrosion-resistant plating,or one coat of
      corrosion-resistant primer and two coats of finish enamel.  The filter
      shall be filled with an impregnating or potting compound that is chemically
      inactive with respect to the filter unit and case.  The compound, either in
      the state of original application or as a result of having aged, shall have
      no adverse effect on the performance of the filter.  The same material
      shall be used for impregnating as is used for filling.  Filter terminals
      shall be copper that can withstand the pull requirements specified and
      measured in accordance with paragraph Terminals Pull Test.

    2.6.2.2   Ratings

      **************************************************************************
                    NOTE:  Indicate maximum current, voltage, and pass
                    band frequency ratings on the drawings.  If no
                    drawings are furnished with the specifications,
                    specify the ratings here.
      **************************************************************************

      [Filters shall be provided in the current, voltage, and frequency ratings
      indicated on the drawings.]  [Filter current shall be [_____].]  [Filter
      voltage shall be [[120] [208] [277] [480] volts, 60 Hz] [[230] [250] [400]
      volts, 50 Hz].]  [The pass band frequencies [_____] Hz to [_____] Hz shall
      be suitable for use with the [50] [_____] [60] [_____] [and] [400] [_____]
      Hz power source and signal line filters as indicated.]

    2.6.2.3   Voltage Drop

      Voltage drop through the filter at operation frequency shall not exceed 2
      percent of the rated line voltage when the filter is fully loaded with a
      resistive load (unity power factor.  Voltage drop measurements shall be in
      accordance with paragraph Voltage Drop Measurements.

    2.6.2.4   Input Elements

      Filters shall be provided with inductive inputs.  If inductive input is
      used then an ESA is required to protect the filter.  The inductor shall
      ensure firing potential for the preceding ESA and shall limit the current
      through the filter capacitor.  The input inductor shall be designed to
      withstand at least a 10,000-volt transient.

    2.6.2.5   Drainage of Stored Charge

      Filters shall be provided with bleeder resistors to drain the stored charge
      from the capacitors when power is shut off.  Drainage of stored charge
      shall be in accordance with NFPA 70.

    2.6.2.6   Insertion Loss

      **************************************************************************
                    NOTE:  Use 100 dB insertion loss at 14 kHz to 10 GHz
                    for applications such as secure communications
                    installations.  For other applications, insert
                    appropriate insertion loss and frequency range for
                    the specific product.  Consult filter manufacturer
                    for detailed requirements.  Also consult the
                    manufacturer when leakage current is important, such
                    as in life safety areas.  There is a tradeoff
                    between leakage current and insertion loss when
                    insertion loss is measured according to MIL-STD 220
                    because of the test connection and the
                    line-to-ground capacitance.  Harmonic loading of EM
                    filters will require alterations to the electrical
                    system design to protect the filters from damage.
                    Large individual loads, such as adjustable speed
                    drive and uninterruptible power supplies, should
                    have shielded isolation transformers on their input
                    line side.  Multiple small individual loads, such as
                    computers, should have EM filters derated or
                    shielded isolation transformers between filter
                    output and the harmonic generating loads.  EM
                    filters should be derated by 50 percent when serving
                    loads with substantial harmonic components.  If a
                    facility is formally required to fully comply with
                    MIL-STD 188 125, filter and ESA characteristics
                    should meet the standard's requirements as applied
                    to the facility.  The facility's electrical system
                    should be designed to meet the requirements of
                    MIL-STD 188 125 with commercially available filters
                    and ESA.  The commercial electrical power feeder
                    should be arranged in a manner that will meet
                    MIL-STD 188 125 requirements.  Voice and data lines
                    should be converted to fiber optics prior to
                    penetration of the EM shield.  The requirements of
                    MIL-STD 188 125 should be applied by a shielding
                    specialist experienced in the standard's
                    requirements and applications.
      **************************************************************************

      Insertion loss shall meet or exceed the levels complying with EM shielding
      effectiveness attenuation requirements herein when measured in accordance
      with MIL-STD 220.  Insertion loss measurements shall be performed in
      accordance with MIL-STD 220 and the paragraph Insertion Loss
      Measurement.

    2.6.2.7   Operating Temperature Range

      Individual filters mounted in the filter enclosure operating at full load
      amperage and rated voltage shall not exceed plus 85 degrees C based on an
      ambient temperature of 65 degrees C outside the filter enclosure.
      Continuous operation from minus 55 to plus 85 degrees C shall be
      demonstrated according to paragraph "Filter Life Test (at Elevated Ambient
      Temperature)".  Filters shall also withstand temperature cycling as
      specified in paragraph "Thermal Shock Test".  The filter shall remain at
      rated voltage and full-load current until temperature equilibrium is
      reached or 24 hours, whichever is greater.

    2.6.2.8   Current Overload Capability

      Filters shall be capable of operating at 140 percent of rated current for
      15 minutes, 200 percent of rated current for 1 minute, and 500 percent of
      rated current for 1 second when tested in accordance with paragraph
      Overload Test.

    2.9.2.9   Reactive Shunt Current

      The reactive shunt current drawn by the filter operating at rated voltage
      shall not exceed 30 percent of the rated full-load current when measured in
      accordance with paragraph Reactive Shunt Current Measurements.

    2.6.2.10   Dielectric Withstand Voltage

      Filters shall be provided which conform to the minimum values of dielectric
      withstanding voltage.  Filter dielectric withstand voltage test shall be in
      accordance with paragraph "Dielectric Withstand Voltage Test".  HEMP
      filters shall be capable of operating continuously at full-rated voltage
      and of withstanding an overvoltage test of 2.8 times the rated voltage for
      1 minute.  In addition, each filter shall be capable of withstanding a
      20-kV or 4-kA peak transient pulse of approximately 20 ns pulsewidth at
      full operating voltage, without damage.

    2.6.2.11   Insulation Resistance

      The insulation resistance between each filter terminal and ground shall be
      greater than 1 megohm when tested in accordance with paragraph Insulation
      Resistance Test.

    2.6.2.12   Parallel Filters (Current Sharing)

      Where two or more individual filters are electrically tied in parallel to
      form a larger filter, they shall equally share the current.  Equally
      sharing is defined to be within 5 percent of the average current.  The
      tests shall be in accordance with paragraph Current Sharing.

    2.6.2.13   Harmonic Distortion

      Harmonics generated by the insertion of a filter shall not increase line
      voltage distortion more than 2.5 percent when measured with a unity power
      factor in accordance with the paragraph Harmonic Distortion Test.

    2.6.3   Marking of Filter Units

      Each filter case shall be marked with HCI tags and with the rated current,
      rated voltage, manufacturer s name, type of impregnating or potting
      compound, operating frequency, and model number.  In addition, individual
      filter cases, the filter enclosures, and supply and load panelboards of
      filtered circuits shall be marked by the manufacturer with the following:

      "WARNING:  Before working on filters, terminals must be temporarily
      grounded to ensure discharge of capacitors."  Nameplates and warning labels

      shall be securely attached.  Nameplates and warning labels shall be
      attached with epoxy.

    2.6.4   Minimum Life

      Filter assemblies shall be designed for a minimum service life of 15 years.

    2.6.5   Power and Signal Line Factory Testing

      **************************************************************************
                    NOTE:  In most cases, test results for equal filters
                    are sufficient to determine compliance with
                    specification requirements.  Factory tests on
                    individual filters may be required for higher than
                    average temperature applications, special filter
                    configurations, and other special project
                    requirements.

                    Filters with nonstandard configuration or ratings
                    may require testing by an independent testing
                    organization.  These ratings would be for filters
                    above 1,000 amperes.
      **************************************************************************

      Factory test report data shall be submitted for each filter configuration,
      voltage, and amperage which shall show the ability of filters to meet the
      specified requirements.  Filter test reports shall be based on prior tests
      of the same filter assembly design and components.  Test data reports shall
      be submitted in accordance with paragraph SUBMITTALS.  Test data shall
      include the following:

      a.  Voltage Drop Measurements.

      b.  Insertion Loss Measurements.

      c.  Filter Life Test.

      d.  Thermal Shock Test.

      e.  Overload Test.

      f.  Reactive Shunt Current Measurements.

      g.  Dielectric Withstand Voltage.

      h.  Insulation Resistance Test.

      i.  Current Sharing.

      j.  Harmonic Distortion.

      k.  Terminals.

    2.6.5.1   Voltage Drop Measurements

      The voltage drop measurements on both ac and dc filters shall be performed
      with the components mounted in the filter/ESA assembly enclosure or mounted
      on a metal plate by the same holding method that will be used for mounting
      in the enclosure.  For ac rated filters, measurements shall be made by
      using expanded scale-type meters.  For dc rated filters, measurements shall
      be made by using a dc meter when the filter is carrying rated current and
      rated voltage.

    2.6.5.2   Insertion Loss Measurements

      Insertion loss measurements for power filters shall have the following
      modifications.  The filters shall be installed in the filter/ESA assembly
      enclosure.  The load current power supply shall operate at the rated
      voltage of the filters and shall be capable of providing any current from
      no-load through rated full-load current.  The rf signal generator shall be
      a swept continuous wave (cw) source.  The buffer networks shall be modified
      to permit valid measurements over the entire frequency band on which
      insertion loss requirements are specified (14 kHz-1 Ghz).  The receiver or

      network analyzer shall be capable of operating over the entire frequency
      band on which insertion loss requirements are specified (14 kHz-1 Ghz).
      Sensitivity shall be adequate to provide a measurement dynamic range at
      least 10 dB greater than the insertion loss requirement.  The load
      impedance shall be resistive and shall be capable of dissipating the rated
      full-load filter current.  Insertion loss measurements shall be made at 20
      percent, 50 percent, and 100 percent of the filter full-load operating
      current.  Insertion loss measurements for communication/signal line filters
      shall be performed the same as for power filters except that the insertion
      loss measurements are required at a load impedance equal to the image
      impedance of the filter.  No load insertion loss measurements shall be
      performed over the frequencies defined in the EM shielding effectiveness
      attenuation requirements for both power and communication filters. [Testing
      shall be load to source for TEMPEST.]  [Testing shall be source to load for
      HEMP.]

    2.6.5.3   Filter Life Test (at Elevated Ambient Temperature)

      This test is conducted for the purpose of determining the effects on
      electrical and mechanical characteristics of a filter, resulting from
      exposure of the filter to an elevated ambient temperature for a specified
      length of time, while the filter is performing its operational function.
      Surge current, total resistance, dielectric strength, insulation
      resistance, and capacitance are types of measurements that would show the
      deleterious effects due to exposure to elevated ambient temperatures.  A
      suitable test chamber shall be used which will maintain the temperature at
      the required test temperature and tolerance.  Temperature measurements
      shall be made within a specified number of unobstructed inches from any one
      filter or group of like filters under test.  This test shall be made in
      still air.  Specimens shall be mounted by their normal mounting means.
      When groups of filters are to be tested simultaneously, the mounting
      distance between filters shall be as specified for the individual groups
      otherwise the mounting distance shall be sufficient to minimize the
      temperature on one filter affecting the temperature of another.  Filters
      fabricated of different materials shall not be tested simultaneously.  The
      test temperature shall be 85 + 2 degrees C.  The length of the test shall
      be for 5,000 hours.  Specified measurements shall be made prior to, during,
      or after exposure.

    2.6.5.4   Thermal Shock Test

      This test is conducted for the purpose of determining the resistance of a
      filter to exposures at extremes of high and low temperatures, and to the
      shock of alternate exposures to these extremes.  Suitable temperature
      controlled systems shall be used to meet the temperature requirements and
      test conditions.  Environmental chambers shall be used to meet test
      requirements and to reach specified temperature conditions.  Filters shall

      be placed so that there is no obstruction to the flow of air across and
      around the filter.  The filter shall be subjected to the specified test
      condition.  The first five cycles shall be run continuously.  After five
      cycles, the test may be interrupted after the completion of any full cycle,
      and the filter allowed to return to room ambient temperature before testing
      is resumed.  One cycle consists of steps 1 through 4 of the applicable test
      condition for dual environmental test chambers (one low temperature and one
      high temperature test chamber) and steps 1 and 3 for single compartment
      test chambers where both high and low temperatures are achieved without
      moving the filter.  The test conditions are as follows:

      1.  -55 deg C. + 0 deg and -3 deg
      2.  25 deg C. +10 deg and -5 deg
      3.  85 deg C. + 3 deg and -0 deg
      4.  25 deg C. +10 deg and -5 deg

      The effective total transfer time from the specified low temperature to the
      specified high temperature shall not exceed 5 minutes.  The exposure time
      in air at the extreme temperatures is a function of the weight of the
      filter.  The minimum exposure time per the weight of the filter shall be as
      follows:

      a.  1 oz. and below 15 minutes

      b.  Above 1 oz. to 4.8 oz.  30 minutes

      c.  Above 4.8 oz. to 3 lb.  1 hour

      d.  Above 3 lb. to 30 lb.  2 hour

      e.  Above 30 lb. to 300 lb.  4 hour

      f.  Above 300 lb.  8 hour

      Specified measurements shall be made prior to the first cycle and upon
      completion of the final cycle, except that failures shall be based on
      measurements made after the specimen has stabilized at room temperature
      following the final cycle.

    2.6.5.5   Overload Test

      Filters shall be mounted in the filter/ESA assembly enclosure or mounted on
      a metal plate by the same holding method that will be used for mounting in
      the enclosure.  A specified current shall then be applied for a specified
      period of time.  After the filter has returned to room temperature, the
      insulation resistance and voltage drop shall be measured.  The insulation
      resistance shall be measured using the method in paragraph "Insulation
      Resistance Test".  AC voltage drop measurements shall be made by using
      expanded scale-type meters which will enable voltage differences of less
      than 1 volt to be read.  DC voltage drop measurements shall be made by
      using a dc reading meter when the filter is carrying rated current and
      rated voltage.  The insulation resistance and the voltage drop shall be
      measured after each separate overload test.  Filters will also be visually
      examined for evidence of physical damage after each test.

    2.6.5.6   Reactive Shunt Current Measurements

      The reactive shunt current measurements shall be performed with the filters
      mounted in the filter/ESA assembly enclosure or mounted on a metal plate by
      the same holding method that will be used for mounting in the enclosure.
      The filter shall be terminated in the inner compartment in an open circuit.
      Rated ac voltage shall be applied between the filter outer compartment
      terminal and the enclosure or metal plate.  The ac current into the outer
      compartment terminal shall be monitored.  The measured current is equal to
      the filter reactive shunt current.

    2.6.5.7   Dielectric Withstand Voltage Test

      The dielectric withstanding voltage test (also called high-potential, over
      potential, voltage-breakdown, or dielectric-strength test) consists of the
      application of a voltage higher than rated voltage for a specific time
      between mutually insulated portions of a filter or between insulated
      portions and ground.  Repeated application of the test voltage on the same
      filter is not recommended as even an overpotential less than the breakdown
      voltage may injure the insulation.  When subsequent application of the test
      potential is specified in the test routine, succeeding tests shall be made
      at reduced potential.  When an alternating potential (ac) is used, the test
      voltage shall be 60 Hz. and shall approximate a true sine wave in form.
      All ac potentials shall be expressed as root-mean-square values.  The KVA
      rating and impedance of the source shall be such as to permit operation at
      all testing loads without serious distortion of the waveform and without
      serious change in voltage for any setting.  When a direct potential (dc) is
      used, the ripple content shall not exceed 5 percent rms of the test
      potential.  A voltmeter shall be used to measure the applied voltage to an
      accuracy of 5 percent.  When a transformer is used as a high-voltage source
      of ac, a voltmeter shall be connected across the primary side or across a
      tertiary winding provided that the actual voltage across the filter will be
      within the allowable tolerance under any normal load condition.  Unless
      otherwise specified, the test voltage shall be dc and shall be as follows:

      a.  DC rated only - 2.5 times rated voltage.

      b.  For filters with ac and dc ratings - 2.5 times rated dc voltage.

      c.  AC rated only - 4.2 times rated rms voltage.

      The duration of the dc test voltages shall be 5 seconds minimum, 1 minute
      maximum, after the filter has reached thermal stability at maximum
      operating temperature produced by passage of rated current.  The test
      voltage shall be applied between the case (ground) and all live (not
      grounded) terminals of the same circuit connected together.  The test
      voltage shall be raised from zero to the specified value as uniformly as
      possible, at a rate of approximately 500 volts (rms or dc) per second.
      Upon completion of the test, the test voltage shall be gradually reduced to
      avoid voltage surges.  The changing current shall be 50 mA maximum.  During
      the dielectric withstanding voltage test, the fault indicator shall be
      monitored for evidence of disruptive discharge and leakage current.  The
      sensitivity of the breakdown test equipment shall be sufficient to indicate
      breakdown when at least 0.5 mA of leakage current flows through the filter
      under test.  The test shall be performed with the components mounted in the
      filter/ESA assembly enclosure.  Filters for ac circuits shall be tested
      with an ac source while filters for dc circuits shall be tested with a dc
      source.  After the test the filter shall be examined and measurements shall
      be performed to include insulation resistance measurements to determine the
      effect of the dielectric withstanding voltage test on specific operating
      characteristics.

    2.6.5.8   Insulation Resistance Test

      This is a test to measure the resistance offered by the insulating members
      of a filter to an impressed direct voltage tending to produce a leakage
      current through or on the surface of these filters.  Insulation-resistance
      measurements shall be made on an apparatus suitable for the characteristics
      of the filter to be measured such as a megohm bridge, megohm-meter,
      insulation-resistance test set, or other suitable apparatus.  The test
      shall be performed with the components mounted in the filter/ESA assembly
      enclosure or mounted on a metal plate by the same holding method that will
      be used for mounting in the enclosure.  The bleeder resistor shall be
      disconnected.  The direct potential applied to the specimen shall be the
      largest test condition voltage (100, 500, or 1,000 volts +10%) that does
      not exceed the rated peak ac voltage or the rated dc voltage.  A separate
      dc power supply may be used to charge the filters to the test voltage.  The
      measurement error at the insulation-resistance value required shall not
      exceed 10 percent.  Proper guarding techniques shall be used to prevent
      erroneous readings due to leakage along undesired paths.
      Insulation-resistance measurements shall be made between the mutually
      insulated points or between insulated points and ground.  The insulation
      resistance value shall be read with a megohmmeter and recorded after the
      reading has stabilized.  When more than one measurement is specified,
      subsequent measurements of insulation resistance shall be made using the
      same polarity as the initial measurements.

    2.6.5.9   Current Sharing

      Testing shall be performed with the filters mounted in the filter/ESA
      assembly enclosure or mounted on a metal plate by the same holding method
      that will be used for mounting in the enclosure.  The filter inner
      compartment terminals shall be loaded with a resistor equal in value to the
      rated operating voltage divided by the sum of the current ratings of the
      devices in parallel.  The resistor shall be capable of dissipating the
      total current.  Rated operating voltage shall be applied at the filter
      outer compartment terminals.  The current into each filter outer
      compartment terminal shall be monitored.

    2.6.5.10   Harmonic Distortion Test

      Harmonic distortion measurements shall be made using a spectrum analyzer
      having a dynamic range of [70 dB] [_____] and a frequency range from [10
      kHz to 1.7 GHz] [_____].  Total harmonic distortion shall be measured at
      the input and output terminals of the filter when operating at 25, 50, and
      100 percent of rated full-load current.

    2.6.5.11   Terminals Pull Test

      The purpose of this test is to determine whether the design of the filter
      terminals can withstand the mechanical stresses to which they will be
      subjected during installation or disassembly in equipment.  Testing shall
      be performed with the components mounted in the filter/ESA assembly
      enclosure or mounted on a plate by the same holding method that will be
      used for mounting in the enclosure.  The force applied to the terminal
      shall be 89 N 20 pounds.  The point of application of the force and
      the force applied shall be in the direction of the axes of the
      terminations.  The force shall be applied gradually to the terminal and
      then maintained for a period of 5 to 10 seconds.  The terminals shall be
      checked before and after the pull test for poor workmanship, faulty
      designs, inadequate methods of attaching of the terminals to the body of
      the part, broken seals, cracking of the materials surrounding the
      terminals, and the changes in electrical characteristics such as shorted or
      interrupted circuits.  Measurements are to be made before and after the
      test.

    2.7   ELECTRICAL SURGE ARRESTERS (ESA)

      **************************************************************************
                    NOTE:  ESA application guidance is found in MIL-HDBK
                    423.
      **************************************************************************

    2.7.1  Power and Signal Line ESA

    2.7.1.1   ESA General

      ESAs shall be metal oxide varistors (MOVs) or spark gaps.  When a spark gap
      is specified, the ESA shall be enclosed within a metal case. Discharges
      shall be contained within the case; no external corona or arcing will be
      permitted.  ESAs shall be factory installed with minimum lead lengths
      within the outer compartment.  For all power filter/ESA assemblies, the
      ESAs shall be installed a minimum of 7.6 cm 3 in apart, with
      terminals at least 7.6 cm 3 in from a grounded surface.  For
      telephone filter/ESA assemblies, the ESAs shall have a minimum clearance
      spacing of 2.5 cm 1 in, and terminals shall be at least 7.6 cm
      3 in from a grounded surface.  Each phase, neutral and telephone
      circuit conductor shall be connected through an ESA to the ground bus.  The
      ESA shall be installed [in the power input compartment of the filter] [in a
      separate EM shielded enclosure].  ESA units within the filter/ESA assembly
      shall be individually replaceable.  Like ESAs shall be interchangeable.
      ESA terminals shall withstand the 89 N 20 lb pull test.  Live parts
      shall be spaced in accordance with NFPA 70.  ESA leads shall be copper.
      Individual ESAs shall be marked with HCI tags and shall be marked with the
      manufacturer's name or trademark and part number.  The ESA shall meet the
      requirements of IEEE C62.11, IEEE C62.41, and UL 1449.

    2.7.1.2    Wiring

      **************************************************************************  *
                    NOTE:  Some designers prefer coiling the wire
                    between the ESA and the filter, because it creates
                    enough inductance to develop the ESA firing
                    potential during transients for HEMP applications.
                    Short leads, as recommended herein, improve the
                    voltage-limiting effectiveness of the ESA.  Fusing
                    of the ESA is not recommended because protection may
                    be lost without the operator's knowledge.  If fusing
                    is necessary, a light to indicate a blown fuse will
                    be provided on the ESA enclosures.
      **************************************************************************

      The ESAs shall be located so that leads of minimum length connect the ESA
      ground terminal to the enclosure.  The total lead length connecting the ESA
      to the filter and the ESA ground terminal to the enclosure shall be less
      than 300 mm. 12 in.  Power line ESA wiring shall be No. 4 AWG
      minimum.  Communication/signal line ESA wiring shall be of the same or
      heavier gauge than the communication/signal line conductor.

    2.7.1.3   Voltage Characteristics

      **************************************************************************
                    NOTE:  Clamping voltage requirement is intended to
                    ensure that the ESA does not have excessive series
                    resistance.  The specific value should be chosen
                    after reviewing manufacturer's data.

                    Specified dc breakdown voltage (or MOV voltage at 1
                    milliampere dc current) for dc and single phase ac
                    power should be in the range of 150 to 200 percent
                    of the peak (not rms) operating voltage.  Use 200 to
                    250 percent on three-phase circuits, so that a
                    short-circuit fault in one phase will not fire ESA
                    on the other two phases.

                    The spark gap dc breakdown voltage requirement is
                    intended to ensure that the spark gap is a
                    low-inductance, fast device.  The precise values are
                    not critical and should be chosen after reviewing
                    ESA catalog information.
      **************************************************************************

      Measurements of (MOV) voltage at 1 mA dc current and spark gap dc breakdown
      voltage shall be made in accordance with the following procedure.  Testing
      shall be performed with the ESAs mounted in the filter/ESA assembly
      enclosure or mounted on a metal plate by the same holding method which will
      be used for mounting in the enclosure.  A variable dc power supply shall be
      connected between the ESA terminal and the enclosure (or plate).  The
      applied dc voltage shall be increased at the rate not to exceed 10 percent
      of the rated firing voltage per second.  The (MOV) voltage at 1 mA dc
      current is the power supply output voltage, when the output current is 1
      milliampere.  The spark gap dc breakdown voltage is the applied voltage
      just prior to breakdown (indicated by a rapid decrease in the voltage
      across the device).  Deenergize the power supply immediately after the
      value has been recorded.  MOV direct current breakdown voltage at 1
      milliampere dc current shall be at least [340] [500] [1,000] [_____] volts
      and less than [425] [1,500] [_____] volts.  MOV testing shall be in
      accordance with IEEE C62.33.  Spark gap direct current breakdown
      (sparkover) voltage shall be at least [500] [1,000] [_____] volts and less
      than [1,500] [3,000] [_____] volts.  Spark gap impulse sparkover voltage of
      the ESA shall be less than 4,000 volts.  This voltage shall be on surges of
      either polarity having a rate of rise of 1,000 volts/nanosecond.  Testing
      of the ESA impulse sparkover voltage shall be performed with the spark gaps
      mounted in the filter/ESA assembly enclosure or mounted on a metal plate by
      the same holding method which will be used for mounting in the enclosure.
      The pulse generator shall be connected between the spark gap terminal and
      the enclosure (or plate) with a minimum inductance connection.  The pulse
      generator shall be capable of providing a ramp voltage of 1 kV/ns to a peak
      voltage which is at least twice the open circuit impulse sparkover voltage.
      Voltage across the spark gap shall be monitored on an oscilloscope or
      transient digitizing recorder, capable of at least 1 ns resolution.  The
      peak transient voltage during the pulse is the impulse sparkover voltage.
      Response time shall be less than 4 nanoseconds.  Clamping voltage of the
      ESA shall be less than [900] [_____] volts at a current pulse of 10 kA.
      ESA clamping voltage measurements shall be performed with the ESAs mounted
      in the filter/ESA assembly enclosure or mounted on a metal plate by the
      same holding method which will be used for mounting in the enclosure.  The
      pulse generator shall be connected between the ESA terminal and the
      enclosure (or plate) with a minimum inductance connection.  The pulse
      generator shall be capable of providing a 10 kA current pulse, on an 8- x
      20-microsecond waveshape into the ESA.  Current through the ESA and voltage
      across the ESA shall be monitored on oscilloscopes or transient digitizing
      recorders.  The asymptotic voltage during the 10 kA portion of the pulse is
      the clamping voltage.

    2.7.1.4   ESA Extinguishing Characteristics

      The ESA shall extinguish and be self-restoring to the normal nonconductive
      state within one-half cycle at the operating frequency.  The ESA
      extinguishing test shall be performed with the ESA mounted in the
      filter/ESA assembly enclosure or mounted on a metal plate by the same
      holding method which will be used for mounting in the enclosure.  The
      extinguishing test shall use an ac power source connected between the ESA
      terminal and ground which shall be at the rated voltage and frequency
      capable of providing at least 25 amperes into a short-circuit load.  A
      pulse generator capable of providing a short pulse which will fire the ESA
      shall also be connected across the ESA.  Voltage across the ESA shall be
      monitored on an oscilloscope or transient digitizing recorder.  A series of
      ten pulses shall be injected.  Performance of the ESA is satisfactory if
      the arc extinguishes (indicated by re-occurrence of the sinusoidal
      waveform) within 8.5 milliseconds after the start of each pulse.

    2.7.1.5   ESA Extreme Duty Discharge Current

      The ESA shall be rated to survive the extreme duty discharge current of a
      single 8- x 20-microsecond pulse with a 10 to 90 percent rise time of 8
      microseconds and fall time to a value of 36.8 percent of peak in 20
      microseconds.  The ESA for high voltage power lines (above 600 volts) shall
      have an extreme duty discharge capability equal to or greater than 70 kA.
      The ESA for low voltage power lines (below 600 volts) to such things as
      building interiors, area lighting, and external HVAC equipment shall have
      an extreme duty discharge capability equal to or greater than 50 kA.  The
      ESAs for control circuits such as interior alarms, indicator lights, door
      access controllers, HVAC controls, and telephones, shall have an extreme
      duty discharge capability equal to or greater than 10 kA.  The ESA extreme
      duty discharge test shall be performed with the ESA mounted in the
      filter/ESA assembly enclosure or mounted on a metal plate by the same
      holding method which will be used for mounting in the enclosure.  A pulse
      generator shall be connected between the ESA terminal and the enclosure (or
      plate) with a minimum inductance connection.  The pulse generator shall be
      capable of supplying an 8- x 20-microsecond waveshape and a only single
      pulse is required.  Current through the ESA and voltage across the ESA
      shall be monitored on oscilloscopes or transient digitizing recorders.  The
      ESA shall be visually monitored during the test and after the pulse
      inspected for charring, cracks, or other signs of degradation or damage.
      Test shall be on a prototype only.  The dc breakdown voltage test shall be
      repeated.

    2.7.1.6  Minimum Operating Life

      **************************************************************************
                    NOTE:  Surge life test will be performed only when
                    required by the user.  Coordinate current amplitude
                    with manufacturer.
      **************************************************************************

      The ESA operating life tests shall be performed with the ESA mounted in the
      filter/ESA assembly enclosure or mounted on a metal plate by the same
      holding method which will be used for mounting in the enclosure.  A pulse
      generator shall be connected between the ESA terminal and the enclosure (or
      plate) with a minimum inductance connection.  The pulse generator shall be
      capable of supplying repetitive 4 kA current pulses, with a 50 ns x 500 ns
      waveshape, to the ESA.  A series of ten pulses is required.  Current
      through the ESA and voltage across the ESA shall be monitored on
      oscilloscopes or transient digitizing recorders.  The ESA shall be visually
      monitored during the series of pulses for indications of external
      breakdown.  The ESA shall be able to conduct 2,000 pulses at a peak current
      of 4 kA and 50 nanoseconds x 500 nanoseconds waveform.  Post-test shall
      include inspection for charring, cracks, or signs of degradation.  The dc
      breakdown voltage test shall be repeated.

    2.7.1.7   Operating Temperature

      The ESA shall be rated for continuous operation in ambient temperatures
      from minus 25 to plus 125 degrees C.

    2.7.2   ESA Testing

      ESA factory test data shall be submitted which shall show the ability to
      meet the requirements herein, based on prior tests of the same ESA assembly
      components and design.  Testing shall be performed with the ESA mounted in
      the filter/ESA assembly enclosure or mounted on a metal plate by the same
      holding method which will be used for mounting in the enclosure.  The pulse
      generator shall be connected between the ESA terminal and the enclosure (or
      plate) with a minimum inductance connection.  Current through the ESA and
      voltage across the ESA shall be monitored on oscilloscopes or transient
      digitizing recorders.  Test data shall include the following:

      a.  Breakdown Voltage.

      b.  Impulse Sparkover Voltage.

      c.  Clamping Voltage.

      d.  Extinguishing.

      e.  Extreme Duty Discharge.

      f.  Surge Life.

    2.8   WAVEGUIDE ASSEMBLIES

      Waveguide-below-cutoff (WBC) protection shall be provided for all piping,
      ventilation, fiber optic cable penetrations and microwave communications
      barrier penetrations of the HEMP electromagnetic barrier.  These WBC
      penetrations shall be protected with cutoff frequencies and attenuation no
      less than the EM shielding effectiveness values listed herein.  The cutoff
      frequencies shall be no less than 1.5 times the highest frequency of the
      shielding effectiveness.  For 1 GHz, the maximum rectangular linear
      diagonal dimension shall be 10 cm 4 inches and the maximum circular
      diameter shall be 10 cm. 4 inches.  The length-to-cell
      cross-section dimension ratio of the waveguide shall be a minimum of [5:1
      to attain 100 dB] [3:1 to attain 50 dB].  Penetration locations shall be
      arranged to facilitate installation and testing by minimizing the number of
      locations.  Waveguides of each assembly type shall be factory tested in
      accordance with IEEE STD 299 and Table I of this specification.

    2.8.1   Waveguide-Type Air Vents

      **************************************************************************
                    NOTE:  Occurrence of dissimilar metals will use
                    corrosion resistant design.
      **************************************************************************

      Each ventilation WBC array shall be a honeycomb-type air vent with a core
      fabricated of corrosion resistant steel as shown on the drawings.
      Waveguide construction shall include heavy frames to dissipate the heat of
      welding to the shield.  A welded WBC array shall be constructed from sheet
      metal or square tubes.  Array cells shall be formed by welding the sheets
      at intersections or welding adjacent tubes along the entire length of the
      WBC section.  The maximum cell size shall be 10 cm 4 in on a
      diagonal.  The length of the WBC section shall be at least five times the
      diagonal dimension of the cells.  Air vents shall be a permanent part of
      the shielded enclosure and shall have a shielding effectiveness equal to
      that of the total enclosure.  Static pressure drop through the vents shall
      not exceed 3.4 gpscm 0.01 inch of water at an air velocity of 305
      m/s. 1000 fpm.  Waveguides for air vents (honeycomb) shall have
      access doors in duct work for maintenance.  The frame of the honeycomb
      panel shall be [welded] [bolted] into the penetration plate [with
      continuous circumferential EM welds.] [with bolts 75 mm 3 inches on
      center.]  Welds for fabrication and installation of honeycomb waveguide
      panels are primary shield welds and shall be inspected as indicated.
      Acceptance testing of all honeycomb panels shall be included with the final
      acceptance test.  No conductors, such as wires and louver operating rods,
      shall pass through the waveguide openings.

    2.8.2   Piping Penetrations

      All piping penetrations of the HEMP barrier to include utility piping, fire
      mains, vent pipes, and generator and boiler exhausts shall be made with
      piping WBC sections.  The WBC material shall be steel with a composition
      suitable for welding to the HEMP shield.  The minimum wall thickness shall
      be 3.2 mm. 0.125 in.  The maximum inside diameter shall be 10
      cm 4 in or a metallic honeycomb insert with a maximum cell dimension
      of 10 cm 4 in shall be installed.  The WBC section shall have an
      unbroken length of at least five diameters to form a minimum cutoff
      frequency of 1.5 times the highest frequency of the shield effectiveness.
      The piping WBC section shall be circumferentially welded or brazed  to the
      HEMP shield, pipe sleeve or a penetration plate as shown on the drawings.
      Generator and boiler exhausts shall be constructed as shown in the drawings
      and shall be configured as a WBC or WBC array.  The circumferential
      penetration welds are primary shield welds and shall be inspected and
      tested as indicated.

    2.8.3   Waveguide Penetrations

      Waveguide penetrations for dielectric fibers or hoses shall be implemented
      in the same manner as piping penetrations.  Dielectric hoses or pipes shall
      be converted to metal waveguide piping before penetrating the shield.  No
      conductors, such as wires and fiber cable strength members, shall pass
      through the waveguide opening.

    2.9   GROUNDING STUD

      **************************************************************************  *
                    NOTE:  Grounding stud will be provided only for
                    small (under 100 square meters (1,000 square feet)
                    of floor area) bolted and welded enclosures.
      **************************************************************************

      Enclosure shall have 13 mm 1/2 inch diameter stud circumferentially
      welded to each side of the shielding penetration plate.

    2.10   PENETRATION PLATES

      Penetration plates shall be minimum 6 mm 1/4 inch thick and sized
      as shown on the drawings.  The penetration plate shall overlap the shield
      penetration cutout dimension by a minimum of 150 mm 6 in on each
      side.  The penetration plate shall be [welded] [bolted] to the HEMP shield
      [with continuous circumferential EM welds.] [with bolts 75 mm 3 in
      on center.]

    2.11   GALVANIZING

      Galvanizing, when practical and not otherwise indicated, shall be
      hot-dipped processed after fabrication.  Galvanizing shall be in accordance
      with ASTM A 123, or ASTM A 653, as applicable.  Exposed fastenings
      shall be galvanically compatible material.  Electrolytic couples and
      dissimilar metals that tend to seize or gall shall be avoided.

    2.12   EM SHIELDED CABINETS AND PULL BOXES

      Cabinets and pull boxes shall be modified NEMA [1] [_____] in accordance
      with NEMA ICS 6 made of corrosion resistant steel of not less than
      1.9837 mm 14 gauge thick with welded seams and galvanized bulkhead
      cover plates.  Access cover plates shall be hinged with EM gaskets and 75
      mm 3 inch maximum bolt spacing.  Design shall include thick cover
      plates, folded enclosure edges, and bolt spacers to prevent uneven gasket
      compression and enclosure deformation.  Gasket shall be easy to replace.
      Gasket contact areas shall be tin-plated using the electrodeposited type I
      method in accordance with ASTM B 545.  Conduit hub shall be
      circumferentially EM welded to the enclosure.  The cabinets shall be
      finished with a corrosion-inhibiting primer and two coats of baked or
      finish enamel.  Cabinets shall be provided with mounting brackets for wall
      mounting or legs for floor mounting.  Cabinets and boxes of each type shall
      be factory tested in accordance with IEEE STD 299 and Table I of this
      specification.

    2.13   QUALITATIVE MONITORING SYSTEM

      A built-in shield monitoring system for SELDS testing shall be provided.
      The system shall consist of either multiple injection points or a surface
      loop system.  Driving conductors shall be brought to a single lockable EM
      shielded connection box, located outside the shield in a controlled space.

    PART 3   EXECUTION

    3.1   INSTALLATION

    3.1.1   Coordination

      The EM shielding installer shall instruct other trades in the presence and
      with the direction of the Government representative, in advance of the EM
      shielding system installation, to ensure that all individuals are aware of
      the critical installation requirements.  Cleaners, solvents, coatings,
      finishes, physical barriers, and door threshold protectors shall be
      provided as required to protect the shielding system from corrosion,
      damage, and degradation.  The shielding installation plan shall be approved
      before construction begins.

    3.1.2   Verification

      Before, during, and after the EM shielding and penetration protection
      subsystem installation, the shielding specialist shall verify and approve
      the installation for compliance with the specifications.  Materials and
      methods, shop drawings, and other items for the shielding subsystem shall
      bear an approval stamp of the shielding specialist.  Compliance
      notification shall be provided to the Contracting Officer before materials
      are installed or methods performed.

    3.1.3   Inspection

      During and after EM shielding and penetration protection subsystem
      installation, including EM filters and waveguides, a qualified shielding
      specialist shall inspect the installation for compliance with the
      specifications.  The inspection shall be done before a finish or concrete
      topping coat is installed.

    3.1.4   Manufacturer's Services

      Services of a manufacturer's representative who is experienced in the
      installation, adjustment, and operation of the equipment specified shall be
      provided.  The representative shall supervise the installation, adjustment,
      and testing of the equipment.

    3.1.5   Posting Framed Instructions

      Framed instructions containing wiring and control diagrams under glass or
      in laminated plastic shall be posted.  Condensed operating instructions,
      prepared in typed form, shall be framed as specified above and posted
      beside the diagrams before acceptance testing of the system.

    3.2   EM SHIELDING ENCLOSURE INSTALLATION (WELDED STEEL CONSTRUCTION)

      **************************************************************************
                    NOTE:  Either the welded construction or bolted
                    construction will be used.  Choose the appropriate
                    construction and delete the non-applicable
                    paragraph.

                    For the EM shielding enclosure, choose either welded
                    or bolted construction.  The unused method should be
                    deleted from the project specification.  Welded
                    construction will usually consist of continuous
                    1.897 mm (14 gauge) thick steel plate and angles to
                    form the enclosure.  Thicker material may be used if
                    it is more cost-effective or required for structural
                    reasons.  Welded construction is used when a
                    shielded facility requires a long maintainable
                    service life of high-level protection, 100 dB
                    attenuation, or HEMP protection, 100 dB.  Bolted
                    construction is associated with a lower level (50
                    dB) of maintained shielding effectiveness.  Bolted
                    construction will usually consist of modular panels
                    bolted together with metal strips or channels.
                    Panels are commonly plywood with steel sheets
                    laminated to one or both sides.  Bolted construction
                    is used when a shielded facility's service life is
                    short, 10 years or less, or the system is required
                    to be demountable for change of location.  This
                    system requires more maintenance than a welded
                    system and requires access to the panels.  The EM
                    shield layout may restrict attenuation testing of
                    the enclosure.  It is desirable for large facilities
                    to place the shield at least 1 meter (3.3 feet)
                    inside the exterior walls, although cost and
                    construction restrict this consideration.  The floor
                    shielding can be tested by SELDS test but not by
                    IEEE STD 299 if it is on grade.  The facility layout
                    must be carefully planned to allow for testing and
                    shield maintenance.
      **************************************************************************

      The EM shielded enclosure shall be installed in accordance with this
      specification, the drawings, and the recommendations of the manufacturer
      and EM shielding specialist.  Shielding steel shall be handled and
      installed carefully to prevent damage.  No penetrations of the shield other
      than those indicated on the drawings will be permitted, including fasteners
      and mounting bolts, without prior written authorization from the
      Contracting Officer.

    3.2.1   Surface Preparation

      Contacting surfaces shall be cleaned and buffed to ensure firm contact with
      shielding steel.

    3.2.2   Control of Warping

      **************************************************************************
                    NOTE:  Steel plates exposed to sunlight and changing
                    environmental conditions increase warpage and
                    buckling.
      **************************************************************************

      Warping of steel shielding plates during installation and welding shall be
      kept within 1 mm in 1 meter. 1/8 inch in 10 feet.  Embeds, drive
      pins, and/or anchor bolts or ties shall be used to hold plates in place
      during welding.  Other techniques such as skip welding shall also be used
      to reduce warpage.  The system chosen shall be fully coordinated and
      approved by the Contracting Officer.  Fasteners, drive pins, and other
      shield penetrations shall be sealed with full penetration circumferential
      EM welds.

    3.2.3   Placement of Floor Shield

      **************************************************************************
                    NOTE:  The shingle overlap method is one successful
                    method of floor shield placement.  Designers have
                    the option to select other methods.
      **************************************************************************

      Placement of the floor shield shall not begin until at least 14 days after
      the pouring of the floor slab and Contracting Officer approval of all
      required submittals.  [The placement of the floor shield shall utilize [the
      shingle overlap method] [_____].]  [Individual floor sheet shall be
      attached on the top and one side only with air-pressure drive tools to the
      floor.  Floor shielding sheets shall be overlapped 50 mm 2 inches
      at joints, bent and laid flat on the concrete floor without voids or gaps,
      and sealed with continuous EM welds at all seams and joints.]  The floor
      shield installation shall start at the center of the space.

    3.2.4   Placement of Overslab

      Before placement of the overslab over any portion of the floor shield, the
      Contracting Officer's approval is required.  Both visual and SELDS testing
      of the shielding within the area to be covered must be successfully
      completed, any defects repaired and retested, and full test results
      supplied to the Contracting Officer prior to placement of the overslab.  A
      vapor barrier shall be placed over the floor shield.

    3.2.5   Welding

      The shielding work shall be provided in accordance with the performance
      criteria specified.  Shielding steel structurally welded to the steel frame
      shall be welded in accordance with AWS D1.1 and AWS D1.3.  EM
      shielding seams shall be sealed EM-tight by the MIG method, using
      electrodes structurally and electrically compatible with the adjacent steel
      sheets.  [Sheet steel shall be welded to support steel by plug or tack
      welding at 300 mm 12 inches on center, and then sheet seams shall
      be continuously EM welded to seal the enclosure] [_____].  Slag inclusions,
      gas pockets, voids, or incomplete fusion shall not be allowed anywhere
      along welded seams.  Weld failures shall be corrected by grinding out such
      welds and replacing with new welds.  A qualified welder shall perform
      welding, both structural and EM sealing.  Weldments critical to shielding
      effectiveness are shown on the drawings and shall be performed in the
      manner shown on the drawings.  Where both structural integrity and
      shielding quality are required for a given weldment, both criteria shall be
      met simultaneously.  Brazing shall conform to the documents discussed
      above, where practicable, and shall also conform to requirement of AWS
      BRH.  Structural, mechanical, or electrical systems penetrations shall be
      sealed by providing a continuous solid perimeter weld, or braze to the
      shield as specified.  All shield joints and seams shall have a minimum 50
      mm 2 inch overlap and shall be sealed with a continuous solid weld.
      After testing, the Contracting Officer shall inspect and approve the
      installation prior to covering by other trades.

    3.2.6   Wall Shielding Attachment

      **************************************************************************
                    NOTE:  The wall attachment method outlined in this
                    paragraph is one successful example.  Site-specific
                    methods must be edited at this point in this
                    specification.  Note that all attachment
                    penetrations must be welded closed.  Metal wall
                    studs or furring strips should be of equal or
                    greater thickness (gauge) than the shield steel when
                    shield steel is welded to supporting metal.
      **************************************************************************

      Continuous [1.613] [_____] mm [16] [_____] gauge thick furring
      channels spaced not more than 600 mm 24 in on center shall be
      secured to steel wall studs by using self-tapping sheet metal screws.  The
      steel sheets shall be tack welded to the furring strips every 400 mm
      16 in on center horizontally and 600 mm 24 in on center
      vertically.  A continuous full penetration EM weld shall be made to join
      the sheets and form the shield.  Welds shall not form dimples or
      depressions causing fish mouths at the edge of the sheet.

    3.2.7   Formed Closures

      Formed closures shall be installed where indicated and/or necessary to
      completely close all joints, openings, enclosures of pipe chases, and
      structural penetrations, columns, and beams.

    3.2.8   Sequence of Installation

      Erection of the steel shall be sequenced to prevent steel sheet warpage.
      Shielding components shall be installed and shall have passed initial
      testing (part 1) before construction of any features that would limit
      access for repairs to the shield.

    3.2.9   Door Assemblies

      Doors shall be mounted to perform as specified.  Door framing shall be
      continuously welded to the EM shield.  The structural system supporting the
      door frame shall provide proper support for doors and frame.

    3.3   EM SHIELDING ENCLOSURE INSTALLATION (BOLTED CONSTRUCTION)

      **************************************************************************
                    NOTE:  Either welded construction or bolted
                    construction will be used.  Choose the appropriate
                    construction and delete the non-applicable
                    paragraph.

                    For the EM shielding enclosure, choose either welded
                    or bolted construction.  The unused method should be
                    deleted from the project specification.  Welded
                    construction will usually consist of continuous
                    1.897 mm (14 gauge) thick steel plate and angles to
                    form the enclosure.  Thicker material may be used if
                    it is more cost-effective or required for structural
                    reasons.  Welded construction is used when a
                    shielded facility requires a long maintainable
                    service life of high-level protection, 100 dB
                    attenuation, or HEMP protection, 100 dB.  Bolted
                    construction is associated with a lower level (50
                    dB) of maintained shielding effectiveness.  Bolted
                    construction will usually consist of modular panels
                    bolted together with metal strips or channels.
                    Panels are commonly plywood with steel sheets
                    laminated to one or both sides.  Bolted construction
                    is used when a shielded facility's service life is
                    short, 10 years or less, or the system is required
                    to be demountable for change of location.  This
                    system requires more maintenance than a welded
                    system and requires access to the panels. The EM
                    shield layout may restrict attenuation testing of
                    the enclosure.  It is desirable for large facilities
                    to place the shield at least 1 meter (3.3 feet)
                    inside the exterior walls, although cost and
                    construction restrict this consideration.  The floor
                    shielding can be tested by SELDS test but not by
                    IEEE STD 299 if it is on grade.  The facility layout
                    must be carefully planned to allow for testing and
                    shield maintenance.
      **************************************************************************

    3.3.1   Enclosure Panel Installation

      Panels shall be installed in accordance with the shielding manufacturer's
      recommendations.  Shielding panels shall be handled and installed carefully
      to ensure that panels are not damaged.  Exposed surfaces shall be cleaned
      of dirt, finger marks, and foreign matter resulting from manufacturing
      processes, handling, and installation.  Electrical conduits shall be
      installed as close to the EM shield as possible.  Framing-joining system
      bolts shall not be used to mount material and equipment.  Material and
      equipment which must penetrate the shielded enclosure shall be seam welded
      or soldered to both shielding surfaces.

    3.3.2   Surface Preparation

      Surfaces shall be cleaned and buffed to ensure good electrical contact with
      shielding surface.  Paint or other coverings on mating surfaces of special
      boxes such as for fire alarm systems, buzzers, and signal lights, including
      areas between box and cover, box and wall, and box and conduit, shall be
      removed.  Insulating material shall be removed to maintain a low-resistance
      ground system and to ensure firm mating of metal surfaces.

    3.3.3   Floor Panel Setting

      A polyethylene film 0.15 mm 6 mil thick vapor barrier shall be
      placed over the structural floor of the parent room before any other work
      is set thereon.  A 3 mm 1/8 inch thick layer of hardboard shall be
      provided over this film with joints loosely butted.  Over this layer an
      additional layer of similar filler material of equal thickness as the
      projection of the framing-joining member from the bottom surface of the
      floor panel shall be provided leaving no more than 6 mm 1/4 inch of
      space between the hardboard and the framing-joining member.

    3.3.4   Framing-Joining System

      Screws shall be tightened with a calibrated adjustable torque wrench so
      equal torque can be set on each screw.  Proper torque values shall be in
      accordance with the manufacturer's requirements.

    3.3.5   Door Assemblies

      The door shall be mounted to perform as required herein.  The door shall be
      through-bolted to the EM shield.

    3.3.6   Filter Installation

      **************************************************************************
                    NOTE:  When it is required that the filter unit be
                    installed inside the shielded enclosure, the input
                    terminal compartment will be EM-tight instead of the
                    load terminal compartment, and the filters will be
                    located in the load terminal compartment.  This
                    arrangement is necessary to prevent radiated EM
                    energy within the shielded enclosure from inducing
                    EM energy in the power conductors between the
                    filters and the point where the conductors pass
                    through the shielded enclosure wall.  To provide for
                    this arrangement, change the wording as necessary;
                    i.e., change the word "load" to read "input" and
                    change the words "input" to read "output" or "load,"
                    as appropriate.
      **************************************************************************

      Filters shall be supported independently of the wall shielding.
      Inspections shall be conducted on filters provided under this
      specification, to verify compliance with the specified requirements.
      Filters shall be shipped after successful testing and shall be examined
      prior to installation to determine if damage occurred during shipment.
      Damage, no matter how slight, will be reason for rejection of the filter.

    3.4   WAVEGUIDE INSTALLATION

      Penetrations of the EM shield shall be treated with the appropriate
      waveguide method.  Waveguides shall be suitable for piping and for fluids
      or gases contained within, in accordance with specified requirements.

    3.5   SHIELDING PENETRATION INSTALLATION

      Penetrations shall be installed in accordance with requirements of the
      penetration schedule and coordinated with system installation.

    3.6   QUALITY ASSURANCE

      Quality Control Plan

      A quality control plan shall be developed to assure compliance with
      contract requirements and quality control records shall be maintained for
      construction operations required under this section.  The quality control
      plan shall be submitted to the Contracting Officer.  A copy of testing
      records, as well as the records of corrective actions taken, shall be
      furnished.  The in-progress and final acceptance testing of EM shielding
      and penetration protection system work shall be performed as specified.
      Deficiencies shall be corrected at no additional cost to the Government.
      Legible copies of the daily inspection reports shall be maintained by the
      shielding specialist at the project site, and the copies of the
      Construction Quality Control Report shall be delivered to the Contracting
      Officer on the third workday following the date of the report.  The daily
      inspections shall include the type of work being performed during the
      report period and locations, type of testing, deficiencies, corrective
      actions, unsolved problems, and recommendations to assure adequate quality
      control.  Results of inspections and tests performed in accordance with
      this specification shall be attached to the daily Construction Quality
      Control Report.

    3.7   SHIELDING QUALITY CONTROL

      The Contractor's organizational structure for shielding quality control
      shall be integrated into the jobsite management.  Testing shall be
      performed by [an independent testing firm] [the shielding installer].

    3.7.1   HEMP Hardness Critical Item Schedule

      Hardness critical items shall be identified during the detail drawing
      submittal period.  These items are those components and/or construction
      features which singularly and collectively provide specified levels of HEMP
      protection, such as the EM shield, surge arresters, EM shielded doors,
      shield welding, electrical filters, honeycomb waveguides, and
      waveguides-below-cutoff.

    3.7.1.1   Performance Test Plan

      A performance test plan shall be submitted for Contracting Officer
      approval.  Testing shall be accomplished in three parts:  (1) in-progress;
      (2) initial shielded enclosure effectiveness; and (3) final acceptance,
      shield enclosure effectiveness.  The test plan shall include equipment
      listings (including calibration dates and antenna factors) and the proposed
      test report format.  The plan shall also include specific test dates and
      durations during the overall construction period so that the Contracting
      Officer may be scheduled to observe the testing and so that repairs may be
      made to the shield and retests conducted.  This separate testing schedule
      for the EM enclosure shall show the points, during construction, when it
      begins and ends as well as a day-by-day test schedule.  The test plan shall
      indicate proposed dates and duration of lowest and highest frequency tests
      so that the Contracting Officer may be available for these final acceptance
      tests.  A test grid shall be identified and the plan for correlation of
      that grid to the structure shall be provided.

    3.7.1.2   Test Reports

      **************************************************************************
                    NOTE:  Specifications and/or quality assurance test
                    results of this paragraph may be classified for some
                    projects.  Provide appropriate instructions when
                    this occurs.
      **************************************************************************

      Test reports shall include the method of testing, equipment used,
      personnel, location of tests, and test results.  Daily reports of results
      of each test performed on each portion of the shielding system shall be
      submitted to the Contracting Officer within 3 working days of the test.
      Location of the area tested shall be clearly identified.  Leaks detected
      during testing shall be identified with sufficient accuracy to permit
      relocation for testing in accordance with test procedures.  Reports of
      testing shall be submitted to the Contracting Officer with required
      certification by the testing agency representative or consultant.  Three
      reports (in-progress test report, initial test report, and final acceptance
      test report) shall be submitted in accordance with the format described
      below.

      Cover Page:
      A cover page is required.

      Administrative Data:
      Test personnel.
      Contract number.
      Date of test.

      Authentication.  Contractor personnel responsible for performance of
      the tests and witnessing organization or representatives.

      Contents:
      Shielded facility description.
      Nomenclature of measurement equipment.

      Serial numbers of measurement equipment.  Date of last calibration of
      measurement equipment.  Type of test performed.  Measured level of
      reference measurements and ambient level at each frequency and test point.
      Measured level of attenuation in decibels at each frequency and test point.
      Dynamic range at each test frequency and test point.  Test frequencies.
      Location on the shielded enclosure of each test point.  Actual attenuation
      level at each test point.

      Conclusions: This section shall include results of the tests in brief
      narrative form.

      Number of Copies of the Report:
      [Three] [_____] copies.

    3.7.2   Field Testing

      **************************************************************************
                    NOTE:  If a facility is required to fully comply
                    with MIL-STD 188 125 by the Joint Chiefs of Staff, a
                    military department headquarters, or a major
                    command, coordinate with the using organization to
                    establish test requirements.  Quality assurance and
                    the testing required by appendix A of that standard
                    should be performed.  However, the using
                    organization may insist on full testing in
                    accordance with appendix B as well.  In that case,
                    advise the user that, based on limited testing to
                    date, no existing EM filter/ESA devices have
                    survived the E-2 and E-3 waveforms.  Include
                    appropriate cost and scheduling considerations if
                    appendix B testing is required.  If MIL-STD 188 125
                    is not a requirement, avoid its reference.
      **************************************************************************

      Testing shall be accomplished in the three parts described below.

    3.7.2.1   Testing - Part 1

      Part 1 shall be in-progress testing and shall include inspection, visual
      seam inspection, and seam testing of all EM shielding materials and
      installation.  [In-progress testing of welded shielding shall include
      testing the structural welds to be embedded prior to concrete placement by
      dye penetrant and magnetic particle testing and 100 percent testing of
      wall, ceiling, and floor shielding welds by the SELDS tests.]  [In-progress
      testing of bolted construction shall include 100 percent testing of floor,
      wall, and ceiling shielding seams by the SELDS testing.]  After successful
      completion of in-progress testing (including defect repairs and retest) and
      with prior approval of the Contracting Officer, placement of embedments
      covering may be made to complete the structural systems.  The Contractor
      shall provide an in-progress test report.

    3.7.2.2   Testing - Part 2

      Part 2 initial testing shall consist of inspection, visual seam inspection,
      seam testing, and shielded enclosure effectiveness testing after shielding
      and shielding penetrations are completed, but before the installation of
      finish materials over the shielding.  Access to penetrations is required.
      All [seams] [welds], including shielding and penetrations not tested in
      part 1, shall be SELDS tested.  The initial shielded enclosure
      effectiveness acceptance test shall consist of a MIL-STD 188 125 test
      utilizing specified test frequencies for magnetic and plane wave.  Testing
      shall be conducted in accordance with the paragraph  EM Shielding
      Effectiveness Testing.  These tests shall be performed with the number of
      shield penetrations limited to those required to support the test.  After
      successful completion of Part 2 initial testing (including defect repairs
      and retest) and with prior approval of the Contracting Officer, placement
      of any covering may be made except in areas where penetrations are located.
      The Contractor shall provide an initial test report.

    3.7.2.3   Testing - Part 3

      Part 3 final acceptance testing shall consist of a visual inspection and a
      shielded enclosure effectiveness test of the EM shielding materials and
      installation.  All [seams] [welds], including shielding and penetrations
      not tested in parts 1 and 2, shall be SELDS tested.  Part 3 testing shall
      be performed upon completion of construction and when the building is ready
      for occupancy.  Facilities requiring HEMP protection shall be tested for
      shielding effectiveness in accordance with acceptance test procedures in
      MIL-STD 188 125.  The Contracting Officer shall be notified in writing
      14 days prior to tests to permit adequate monitoring by authorized
      representatives.  Corrective work shall be accomplished immediately upon
      detection that any area has failed to meet the requirements specified.
      Retesting shall be performed to verify that remedial work done to meet the
      required attenuation has been properly installed.  The Contractor shall
      provide a final acceptance test report.

    3.7.3   Weld Inspection

      **************************************************************************
                    NOTE:  Additional welding tests may be specified,
                    such as ultrasonic or radiographic tests, but these
                    tests are costly.
      **************************************************************************

      The weld seams shall be visually inspected by a qualified welder during the
      welding operation and after welding is completed.  Completed welds shall be
      inspected after the welds have been thoroughly cleaned by hand or power
      wire-brush.  Welds shall be inspected with magnifiers under bright light
      for surface cracking, porosity, slag inclusion, excessive roughness,
      unfilled craters, gas pockets, undercuts, overlaps, size, and insufficient
      throat and concavity.  Defective welds shall be ground out and replaced
      with sound welds.

    3.7.4   Shielded Enclosure Leak Detection System (SELDS) Testing

      **************************************************************************
                    NOTE:  SELDS testing the welds in the floor
                    shielding is usually performed on the interior only
                    because it is not possible to "sniff" on both sides
                    (assuming the shield is on the ground level).  Dye
                    penetrant may also be used to test the welds where
                    SELDS testing is not possible.  The SELDS can be
                    obtained commercially from the following:  1.
                    Carnel Labs Corporation 21434 Osborne Street Canoga
                    Park, CA 91304 Telephone:  (818) 882-3977 2.
                    Rayproof Shielding Systems Corporation 50 Keeler
                    Avenue Norwalk, CT 06854 Telephone:  (203) 838-4555
                    3.  Retlif Corporation 795 Marconi Avenue
                    Ronkonkoma, NY 11779 Telephone:  (516) 737-1500
      **************************************************************************

      The leak detection system shall use a 95- to 105-kHz oscillator and a
      battery operated hand-held receiver.  The receiver or "sniffer" shall have
      a ferrite loop probe capable of sensing leaks within 6 mm 1/4 inch
      of the probe location with a dynamic range of 140 dB.  Testing shall be
      conducted in accordance with test equipment manufacturer's instructions.
      Test loops or leads shall be placed under the shield floor or into
      inaccessible locations prior to installation to assist in the detection of
      seam leaks in the floor, ceiling and walls.  The loop or lead wires shall
      be placed between the vapor barrier and the structural slab for the floor
      shield with the leads brought to an accessible location.  The test leads
      shall be insulated stranded copper conductors 2-2.5 mm in diameter and
      bonded to the shield only at the end.  Test leads shall be placed in
      plastic conduit for protection and shall not exceed 45 m 150 ft in
      length.  The surface area of the shield will determine the number of test
      leads (drive points) that are required.  Drive points shall be installed on
      the shielding exterior and attached to two sets of diagonally opposing
      corners during construction.  The distance between test lead connections on
      a shield surface shall not be more than 20 m. 66 ft.  The maximum
      testing area shall be 400 sm. 4300 sf.  If the shield area exceeds
      this requirement, additional drive points shall be provided.  Bonding of
      the test leads to the shield is accomplished by brazing or high-temperature
      soldering.  Test leads from the drive points shall be run to a lockable
      test cabinet for connection to the SELDS oscillator.  If more than one test
      cabinet is required for a given area or building, test leads that would be
      common to different surface areas shall be duplicated at each test cabinet
      to ensure that test point parings are maintained.  The Contractor shall
      record the location of the permanent test leads and shall provide this
      information to the Contracting Officer for permanent reference.  Welds and
      seams shall be 100 percent tested.  Seams shall be continuously probed with
      the test receiver set to detect abrupt changes of shielding level greater
      than 10 dB on the shielding unit scale.  Points having a change greater
      than 10 dB shall be clearly marked and shall have the weld repaired to meet
      the specified requirement.  Each repaired point shall be retested until
      there are no points on seams which fail the test.

    3.7.5   EM Shielding Effectiveness Testing

      Services of an EM shielding testing specialist, approved by the Contracting
      Officer, shall be furnished to test the shielded enclosure.  The laboratory
      shall be equipped and staffed to perform field tests of EM shielded
      enclosures and shall perform these tests as a normal service.  Test
      equipment used shall have been calibrated within the last 12 months.

    3.7.5.1   Test Procedure

      Test procedure and equipment shall be similar to that specified in
      MIL-STD 188 125.  Test frequencies are specified herein.  Test points
      shall be as indicated in Table I.  The grid shall be arranged such that
      corner points of the grid occur at the intersection of three planes (two
      wall surfaces and ceiling or two wall surfaces and floor).  Measurement
      data at all test points shall be recorded, and a grid map for each surface
      tested shall be provided.  For any test point where required attenuation is
      not provided, the Contractor shall correct the discrepancy and retest.
      Both the results of the test failure and the successful results shall be
      provided. Enclosure effectiveness test for magnetic attenuation shall be
      performed with the antennas located directly opposite each other and
      separated by a distance of 600 mm 2 ft plus the wall thickness.
      Plane wave attenuation tests shall be performed with the antennas located
      directly opposite each other and with the transmitting antenna placed 300
      mm 1 ft away from the enclosure wall and with the receiving antenna
      set 300 mm 1 ft from the wall for stationary measurements and 50
      mm to 600 mm 2 in to 2 ft from the wall for swept measurements.  The
      magnetic field test and the plane wave test should follow the following
      test sequence.  The calibrations shall be performed at the beginning of
      each test day.  Then the test area shall be set up for the 100 to 400 MHz
      stationary measurement in on to the two required polarizations.  With the
      transmitter off check the receiver sensitivity.  Energize the transmitter,
      and record the fixed measurement data.  Remove the receiving antenna from
      the test stand and perform the swept measurement at the same frequency and
      transmitting antenna polarization.  Rotate the transmitting antenna, and
      perform the second 100 to 400 MHz stationary measurement.  Perform the
      swept measurement for the second transmitting antenna polarization.
      Reconfigure the equipment for the 900 to 1000 MHz test frequency, and
      repeat the series of four measurements.  To perform the swept measurement,
      the receiving antenna is removed form the test stand and held with a
      dielectric rod at least 300 mm 12 in in length.  A dielectric
      spacer should be attached to the sweeping antenna to assist in maintaining
      the 50 mm 2 in distance from the shield.  A rapid sweep to locate
      hot spots  is made by rotating the polarization and waving the antenna
      through the specified volume.  The final activity of each test day will be
      to repeat the calibrations and verify the consistency with the previous
      calibration results.  Test procedures shall include a definition of all
      test points including but not limited to walls, door frames, accessible
      joints, and around filters and penetrations.  Each EM door shall be tested
      at the locations indicated in Table I.

                                   TABLE I - SHIELDING EFFECTIVENESS TEST POINTS

                               Testing Location              Test Points Spacing

    Joints between steel panels for        Test every 3 m
    roof, walls, and floors                (minimum of one test point per corner
                                           seam)

    Corner seams for walls to floor,       Test every 3 m
    walls to roof, and wall to wall        (minimum of one test point per corner
                                           seam)

    Corners (intersection of               Test at all corners in shield
    three surfaces)

    Single doors                           Test at each corner; at midpoint
                                           of each side longer than 1.5 m
                                           and at center

    Double doors                           Test each separately at same test
                                           point as single doors

    WBC vents and panels                   Test in center (on axis) for all
                                           sizes (including single); at all
                                           four corners if 300 by 300 mm
                                           or larger; and at the
                                           midpoint of each side longer than 1.5
                                           1.5 m

    At treated penetrations of             Test as close to "on-axis" as
    shield (and entry panel and            possible, or orient for maximum
    backshield)                            signal

    All other shield joints,               Sweep all surfaces at one frequency in
    seams, or corners                      the range of 400 MHz to 1 GHz.
                                           Test every 3 m max. plane wave

    Doors                                  Door handles

    EM filter enclosures                   Test at each seam corner and midpoint

                                           of each side longer than 1.5 m
                                           at center

    EM cabinets and enclosures             Test at each seam corner and each side
                                           1.5 m on center

      NOTE 1.  Each point shall be swept in space 600 mm around the point.

                                   TABLE I - SHIELDING EFFECTIVENESS TEST POINTS

                               Testing Location              Test Points Spacing

    Joints between steel panels for        Test every 10 ft (NOTE 1)
    roof, walls, and floors                (minimum of one test point per corner
                                           seam)

    Corner seams for walls to floor,       Test every 10 ft (NOTE 1)
    walls to roof, and wall to wall        (minimum of one test point per corner
                                           seam)

    Corners (intersection of               Test at all corners in shield
    three surfaces)

    Single doors                           Test at each corner; at midpoint
                                           of each side longer than 5 ft
                                           and at center

    Double doors                           Test each separately at same test
                                           point as single doors

    WBC vents and panels                   Test in center (on axis) for all
                                           sizes (including single); at all
                                           four corners if 12 in by 12 in
                                           or larger; and at the
                                           midpoint of each side longer than
                                           5 ft

    At treated penetrations of             Test as close to "on-axis" as
    shield (and entry panel and            possible, or orient for maximum
    backshield)                            signal

    All other shield joints,               Sweep all surfaces at one frequency in
    seams, or corners                      the range of 400 MHz to 1 GHz.
                                           Test every 10 ft max. plane wave

    Doors                                  Door handles

    EM filter enclosures                   Test at each seam corner and midpoint
                                           of each side longer than 5 ft at
                                           center

    EM cabinets and enclosures             Test at each seam corner and each side
                                           5 ft on center

      NOTE 1.  Each point shall be swept in space 2 ft around the point.

    3.7.5.2   Test Points

      Additional test points shall be measured in accordance with MIL-STD 188
      125 for facilities requiring HEMP protection.  Test points include the
      periphery of doors and covers, handles, latches, power filter penetrations,
      air vent filters, communications line filter penetrations, and points of
      penetration by pipes, tubes, and bolts.

    3.7.5.3   Test Methodology

      Antennas shall be oriented for maximum signal pickup.  Each test point
      shall be probed for area of maximum leakage, such as around door frames,
      accessible joints, filters, pipes, and air ducts.  Magnitude and location
      of maximum signal levels emanating from the enclosure shall be determined
      for each accessible wall at a minimum of two locations on each wall, around
      doors, and at penetrations and seams of the enclosure.  Measurement of
      attenuation shall be accomplished in accordance with Table I.

    3.7.5.4   Test Frequencies

      **************************************************************************
                    NOTE:  Test frequencies will be in accordance with
                    MIL-STD 188 125 when applicable.
      **************************************************************************

      Testing frequencies for shielded enclosures shall be as follows:

      [Magnetic field:  [14 kHz,] [400 kHz,] and [10.1 MHz] [_____].
      Electric field:  [200 kHz] and [16 MHz] [_____].
      Plane wave:  [100 MHz], [415 MHz], and [1.29] [18] [_____] [GHz].]

      [MIL-STD 188 125 frequencies are as follows:

      Magnetic:  [_____]
      Plane wave:  [_____]]

    3.7.6  Weld Testing

      Structural welds to be embedded shall be tested in accordance with AWS
      D1.1 using magnetic particle inspection or dye penetrant inspection and a
      100 percent of the shielding seams by the SELDS testing prior to embedment.

    3.8   GROUNDING

      **************************************************************************
                    NOTE:  Grounding method will be in accordance with
                    MIL-STD 188 124.  An equipotential ground plane is
                    recommended for shielded facilities.
      **************************************************************************

      The contract drawings indicate the extent and general arrangement of the
      shielded enclosure grounding system.  The grounding methods shall be an
      equipotential grounding plane method in accordance with UL 1283, NFPA
      70, NFPA 77, NFPA 780, IEEE STD 142, MIL-STD 188 124, and
      MIL-HDBK 419.  For additional facility grounding requirements, see
      Section 16415 ELECTRICAL WORK, INTERIOR.

    3.9   FIELD TRAINING

      A field training course shall be provided for designated operating and
      maintenance staff members.  Training shall be provided for a total period
      of [8] [_____] hours of normal working time and shall start after the
      system is functionally complete but prior to the final acceptance test.
      Field training shall cover all the items contained in the operating and
      maintenance manuals.

              -- End of Section --