Attachment 8 - MIL-STD-1310.pdf

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INCH-POUND

MIL-STD-1310G(NAVY)

28 JUNE 1996

SUPERSEDING

MIL-STD-1310F(NAVY)

30 DECEMBER 1992

DEPARTMENT OF DEFENSE

STANDARD PRACTICE FOR SHIPBOARD BONDING,

GROUNDING, AND OTHER TECHNIQUES

FOR ELECTROMAGNETIC COMPATIBILITY

AND SAFETY

AMSC N/A AREA EMCS

DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.

MIL-STD-1310G(NAVY)

ii

FOREWORD

1. This military standard is approved for use by the Department of the Navy and is available for use by all Departments and Agencies of the Department of Defense.

2. Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: Commander, Naval Sea Systems Command (NAVSEA), ATTN: SEA 55Z3, 2531 National Center Building 3, Washington, DC 20362-5160 by using the Standardization Document Improvement Proposal Form (DD 1426) appearing at the end of this document or by letter.

3. The increased use of electrical and electronic equipment aboard naval ships introduces electromagnetic interference (EMI) problems to ship operation and per-formance. As systems are added, they all contribute and become susceptible to an intense electromagnetic environment (EME). Considering the corrosive salt water environment in which ships must operate and the interaction of a ship's electrically conduc tive metallic superstructure, topside hardware, antenna systems, etc., the potential for interoperability problems is significantly increased. Potential EMI and personnel safety problems related to electronic equipment operating in these envir onments are magnified because of: (a) the need to establish and maintain a low imped ance (Z), common reference ground for all electrical/electronic equipment, and

(b) the detrimental effects of: (1) natural and manmade, (2) spurious and intent ional,

(3) off-ship and own-ship, electromagnetic (EM) energy.

4. To provide for shipboard EM compatibility ( EMC) and safe operation, this revision of MIL-STD-1310 has been expanded to provide additional requirements and guidance for EMI prevention and safe operation in the following EM environmental e ffects (E ) areas3 of concern.

! The ship's common ground plane ! Hull-generated EMI control ! Hull-penetration EMI ! Cable and case penetration/radiation EMI ! Superstructure blockage/reflections, EM signature reduction ! Equipment-generated EMI prevention ! Electrical safety ground

5. This document does not specify EMI reduction through frequency selection, limits on operating power, or use of blankers, and specifies or recommends only limited requi rements related to equipment design, location and multicoupler use. Grounding for personnel safety continues to be a major part of this military standard, particu-larly in regard to commercial-off-the-shelf (COTS) equipment and non-developmental items (NDI). A separate appendix is included herein with procedures to identify whether COTS/NDI equipment meets appropriate safety requirements herein before use, and to provide direction to bring them into conformance when necessary. This do cument does identify the E inspection and test procedures that can be used as measures of3 effect iveness of the EM control and personnel safety measures when installed/implemented.

6. Recent Department of Defense (DoD) acquisition policy changes encour age contractor innovation, introduction of advancing technology, and determination of the appro priate methods and materials to be used for all DoD acquisitions. This document implements this policy by use of the permissive "should" in many areas where the mandatory "shall" previously was used. Many effective shipboard EMI control measures and materials have been identified by the government and subsequently specified as requirements for ship construction and availabilities. Mandating compliance works to the possible exclusion of equally effective industry-developed solutions. To avoid that possibility, when appropriate, this document defines EMC and safety require ments;

prese nts yesterday's (proven effective) solution(s) which have met them, but allows the contractor an option to innovate a new solution by use of the permissive "sh ould."

Because the appropriate performance demonstration inspections and tests have been identified herein, whichever method/material is used, its effectiveness in meeting the requirement can be determined.

iii

CONTENTS

PARAGRAPH TITLE PAGE

1. SCOPE

1.1 Scope

1.2 Application

1.3 Tailoring

2. APPLICABLE DOCUMENTS

2.1 Government documents

2.1.1 Specifications, standards, and handbooks

2.1.2 Other Government documents, drawings, and publications

2.2 Non-Government publications

2.3 Order of precedence

3. DEFINITIONS

3.1 Acronyms used in this standard

3.2 Bond

3.3 Bond classification

3.4 Bond strap

3.5 Bright metal

3.6 Broadband noise (BBN)

3.7 Commercial-off-the-shelf (COTS)

3.8 Computer ground system

3.9 Conduit

3.10 Electrical surge suppressor, marine type

3.11 Electromagnetic compatibility (EMC)

3.12 Electromagnetic environmental effects (EME)

3.13 Electromagnetic interference (EMI)

3.14 Electromagnetic pulse (EMP)

3.15 Ground (ground potential)

3.16 Ground loop

3.17 Ground, personnel safety

3.18 Ground, radio frequency (RF)

3.19 Ground, 360 degrees (peripheral)

3.20 Grounding

3.21 Intermodulation interference (IMI)

3.22 Maintenance related EMI

3.23 Mobile-transportable electrical equipment

3.24 Nonlinear junction

3.25 Non-developmental item (NDI)

3.26 Non-topside areas

3.27 Portable equipment

3.28 Shield

3.29 Shielded area

3.30 Terminal protection device (TPD)

3.31 Topside areas

3.32 Trunk, wireway

4. GENERAL REQUIREMENTS

4.1 Performance requirements

4.1.1 Grounding; ship's ground potential

4.1.1.1 Common reference ground plane

4.1.1.2 Class B and class C bonding and grounding for EMC

4.1.1.2.1 Metal-to-metal contact at bonded junction(s)

4.1.1.2.2 Preservation of bolted mating surfaces

4.1.1.2.3 Bond strap installation

4.1.2 Hull-generated EMI

4.1.2.1 General requirements for hull-generated EMI control

4.1.2.2 Corrective action for hull-generated EMI

4.1.3 Hull and cable penetration EMI

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CONTENTS (Continued)

PARAGRAPH TITLE PAGE

4.1.3.1 Cable shielding

4.1.3.2 Hull penetrations

4.1.4 Superstructure blockage and reflections

4.1.5 Equipment-generated EMI prevention

4.1.5.1 Equipment-generated IMI

4.1.5.2 BBN suppression; portable electrical tools

4.1.6 Electrical safety; personnel shock hazard prevention

4.2 Performance demonstration

4.2.1 Ground plane and hull-generated EMI control

4.2.2 Hull-penetration EMI

4.2.3 Cable and case penetration/radiation EMI

4.2.4 Superstructure blockage/reflections, EM signature reduction . . 9

4.2.5 Equipment-generated IMI prevention

4.2.6 Electrical safety ground

5. DETAILED REQUIREMENTS

5.1 Ground potential and ship's ground plane(s)

5.1.1 Ground potential

5.1.1.1 Ground potential for metallic hull ships

5.1.1.2 Ground potential for nonmetallic hull ships

5.1.1.2.1 Ground plate location

5.1.1.2.2 Connection of the cable ground system

5.1.2 Ground plane(s)

5.1.2.1 Elements of the ground plane

5.1.2.1.1 Superstructure, equipment foundations and racks

5.1.2.1.2 Cable grounding system's branches

5.1.2.1.3 Shielded room(s)

5.1.2.1.4 Computer ground system

5.1.2.2 Grounded items

5.1.2.2.1 Equipment cabinets and hardware items

5.1.2.2.2 Shock-mounted

5.1.2.2.3 Large hardware items

5.1.3 Class B and class C bonding and grounding

5.1.3.1 Class B and C bond installation

5.1.3.2 Hardware for Class B and C bonding

5.1.3.3 Class C bond straps

5.1.3.3.1 Type I bond strap

5.1.3.3.2 Type II bond strap

5.1.3.3.3 Type III bond strap

5.1.3.3.4 Type IV bond strap

5.2 Hull-generated EMI prevention

5.2.1 Nonmetallic topside material

5.2.2 Topside stowage

5.2.2.1 Portable and removable metallic deck hardware

5.2.2.2 Other metallic material

5.2.3 Insulate topside metal-to-metal contact junctions

5.2.4 Bond topside metal-to-metal contact junctions

5.3 Cable and hull penetration EMI control

5.3.1 Topside cable installations

5.3.1.1 Shielded cable

5.3.1.2 Unshielded cable

5.3.1.3 Wireway trunks

5.3.2 Hull penetration EMI

5.3.2.1 Bonding metallic hull-penetrators

5.3.2.1.1 Rigid conduit

5.3.2.1.2 Flexible conduit

5.3.2.1.3 Waveguides, pipes, tubing, and exhaust stacks

5.3.2.2 Shielding effectiveness (SE)

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CONTENTS (Continued)

PARAGRAPH TITLE PAGE

5.3.2.3 Signal cables penetrating the hull

5.3.3 Below decks cable installations

5.4 Superstructure blockage and reflections

5.4.1 Topside configuration drawings

5.4.2 Flat and reflective surfaces

5.5 Equipment-generated IMI prevention

5.5.1 Wideband receiver front-end stages

5.5.2 RF-tuned receiver front-end stages

5.5.3 LF-MF receiver(s) but no in-band transmitter(s)

5.5.4 Active wideband receiver coupler systems

5.6 Electrical safety; personnel shock hazard prevention

5.6.1 Portable and mobile-transportable electrically-powered equipment 15

5.6.1.1 Electrical equipment with a conductive case

5.6.1.2 Electrical equipment with a non-conductive case

5.6.2 Fixed-installed, electrically-powered equipment

6. NOTES

6.1 Intended use

6.2 Issue of DODISS

6.3 Subject term (key word) listing

6.4 RF impedance measurement

6.5 Changes from previous issue

FIGURES

1. EMI filter capacitor installation in sound powered telephone boxes. . . 18

2. Wireway trunk

3. Cable shield, metal pipe, metal tubing, and rigid conduit grounding . . 20 4a. Cable shielding method, flexible conduit 4b. Cable shielding method, flexible conduit (continued)

5. Waveguides grounding

APPENDIX A CLASS B AND CLASS C BOND INSTALLATION

PARAGRAPH

A.1 SCOPE

A.2 APPLICABLE DOCUMENTS

A.3 DEFINITIONS

A.4 GENERAL REQUIREMENTS

A.5 DETAILED REQUIREMENTS

A.5.1 Bonding by direct metal-to-metal contact A.5.1.1 Paint, preservative, corrosion and contaminant removal . . 27 A.5.1.2 Clean surface(s) A.5.1.3 Enhance conductivity, expel contaminants, retard corrosion 27 A.5.1.4 Bolt to the mating surface A.5.1.5 Seal and preserve the junction A.5.2 Bonding with conductive faying material A.5.2.1 Surface preparation A.5.2.2 Pre-fit faying material A.5.2.3 Bolt to the mating surface A.5.2.4 Seal and preserve the junction A.5.3 Bonding with non-conductive (insulating) faying material . . . 28 A.5.3.1 Surface preparation A.5.3.2 Pre-fit faying material A.5.3.3 Bolt to the mating surface A.5.3.4 Seal and preserve the junction vi

CONTENTS (Continued)

FIGURES TITLE PAGE

A-1 Antenna tuner and coupler grounding A-2 Methods of attaching bond straps

APPENDIX B ELECTRICAL SAFETY AND PROTECTION FOR COTS AND NDI EQUIPMENT . . 29

PARAGRAPH

B.1 PURPOSE

B.2 COTS/NDI ELECTRICAL AND ELECTRONIC EQUIPMENT

B.3 ELECTRICAL SHOCK HAZARD PROTECTION REQUIREMENTS

B.3.1 Double insulated and non-conducting equipment B.3.1.1 Double insulated equipment B.3.1.2 Non-conducting equipment B.3.2 Equipment with a conductive case or exposed conductive elements 30 B.3.2.1 Installation requirements; 3-pronged plug B.3.2.2 Installation requirements; 2-pronged plug B.4 Power line SURGE PROTECTION FOR MOBILE ELECTRICAL EQUIPMENT . . 30 B.4.1 Separate single-phase circuit B.4.2 Power line strip surge suppressors for marine use

APPENDIX C NONMETALLIC HULL SHIPS CABLE GROUND SYSTEM FABRICATION

C.1 PURPOSE

C.1.1 Primary common ground reference; systems and shielded spaces . 32 C.1.2 Common ground reference outside shielded spaces C.1.3 Common ground reference inside shielded spaces C.1.4 Electrical safety ground for shock hazard protection

C.2 GROUND SYSTEM CABLES

C.2.1 Ground cable installation C.2.2 Ground plate interconnecting cable C.2.3 Main ground cable C.2.4 Branch ground cables C.2.5 Electronic transmitter ground cable C.2.6 Antenna tuners and couple rs, ground cable C.2.7 Lightning protection C.2.8 Metal mast

C.3 EQUIPMENT/ITEMS GROUNDING REQUIREMENTS

C.3.1 Equipment/items that should be grounded C.3.2 Items that should not require grounding

C.4 GROUNDING TO SHIELDED AREA

C.5 CONNECTIONS

FIGURES

C-1a Nonmetallic hull ship multi-tree ground system C-1b Nonmetallic hull ship multi-tree ground system (continued)

1. SCOPE

1.1 Scope . This document specifies the performance requirements for shipboard bonding, grounding and shielding; identifies requirements for EMI control in the areas of hull-generated and equipment-generated EMI, hull and cable penetration EMI, and superstructure blockage/reflections; specifies requirements for protection of perso nnel from electrical shock, and identifies the applicable requirements for measuring the effectiveness of EMI control and safety measures implemented when requirements herein are invoked.

1.2 Application . The requirements specified herein apply to metal and non-metallic hull ships and are applicable during ship construction and ship overhaul, alter ation or repair availabilities. Requirements herein may be invoked upon contractor and government (military and civilian) personnel.

1.3 Tailoring . The requirements herein may be subject to deletion tailoring, such that o nly those items that pertain to a specific ship are specified in the solicitation or contract. Due to cost impact:

a. The shielding provisions for electromagnetic pulse (EMP) protection herein are to be implemented only when specified, and

b. Replacement of bond straps with later approved versions is not recommended or required, unless inspection or testing indicates a need for such action.

2. APPLICABLE DOCUMENTS

2.1 Government documents .

2.1.1 Specifications, standards, and handbooks . The following specifications, standards and handbooks form a part of this document to the extent specified therein.

Unless ot herwise specified, the issues of these documents are those listed in the Depar tment of Defense Index of Specifications and Standards (DoDISS) and supplement thereto, cited in the solicitation (see 6.2).

SPECIFICATIONS

FEDERAL

FF-N-836 - Nut, Square, Hexagon, Cap, Slotted, Castle, Knurled, Welding and Single Ball Seat.

FF-W-84 - Washers, Lock (Spring).

FF-W-92 - Washers, Flat (Plain).

MILITARY

MIL-A-907 - Antiseize Thread Compound, High

Temperature.

MIL-S-1222 - Studs, Bolts, Hex Cap Screws, Socket

Head Cap Screws, and Nuts.

MIL-T-22361 - Thread Compound; Antiseize, Zinc Dust-

Petrolatum.

MIL-S-22698 - Steel Plate, Shapes and Bars, Weldable

Ordinary Strength and Higher Strength:

Structural.

MIL-S-24235 - Stuffing Tubes, Metal, and Packing Assemblies for Electric Cables, General Specification for.

MIL-C-24643 - Cable and Cords, Electrical, Low Smoke, for Shipbo ard Use, General Specification for.

MIL-DTL-24749 - Grounding Straps and Bosses, Electro-magnetic ( Inch-Pound), General Specification for.

SPECIFICATIONS (Continued)

MILITARY (Continued) MIL-C-24758 - Conduit, Flexible, Weatherproof, and

Associated Fitt ings General Specification for.

MIL-S-45180 - Sealing Compound, Gasket, Hydrocarbon Fluid and Water Resistant.

STANDARDS

MILITARY

DOD-STD-1399-406 - Interface Standard for Shipboard

Systems Section 406 Digital Computer Grounding (Metric).

MIL-STD-882 - System Safety Program Requirements

NAVAL SEA SYSTEMS COMMAND (NAVSEA)

S9407-AB-HBK-010 - Handbook of Shipboard Electromagnetic

Shielding Practices.

(Unless otherwise indicated, copies of federal and military specifications, stan dards, and handbooks are available from the Standardization Documents Order Desk, Bldg. 4D, 700 Robbins Avenue, Philadelphia, PA 19111-5094.)

2.1.2 Other Government documents, drawings, and publications . The following other Gov ernment documents, drawings and publications form a part of this document to the extent specified herein. Unless otherwise specified, the applicable issues are those cited in the solicitation.

DRAWINGS

NAVAL SHIP SYSTEMS COMMAND (NAVSHIPS)

804-4477903 - Staff, Jackstaff and Ensign GRP.

804-4563125 - Climber Safety Rail Notched Tube Type

Arrangement and Details.

(Copies of above drawings are available from Commander, Portsmouth Naval Shipyard, Naval Engineering Drawing Support Activity, Code 202.2, Portsmouth, NH 03804-5000.)

NAVAL SEA SYSTEMS COMMAND (NAVSEA)

407-5287561 - Industrial Electromagnetic Compatibil-ity (IEMC) Work Process Instructions.

407-5291780 - Standard Electromagnetic Interference

(EMI) Survey Procedures.

(Copies of above drawings are available from Commander, Naval Sea Systems Command, SEA 03K23, Washington, DC 20362-5160.)

803-5000903 - Liferail System (GRP).

803-5000938 - Lifeline and Awning Stanchions (GRP).

803-5184097 - Safety Nets, Deck Edge GRP or AL FR.

803-5184099 - Inclined Ladder for Exterior Locations, Glass Reinforced Plastic (GRP).

804-5184155 - Liferails, Lifelines and Awning

Stanchions (AL & STL) Details and L/M.

804-5959308 - Lifeline System, Kevlar, Assembly and

Testing.

(Copies of above drawings are available from Commander, Portsmouth Naval Shipyard, Naval Engineering Drawing Support Activity, Code 202.2, Portsmouth, NH 03804-5000.)

DRAWINGS (Continued)

NAVAL AIR ENGINEERING CENTER (NAEC)

28638-6SE00063 - Avionic Workbench, Deck Support and

Ground Installation Drawing.

(Copies of above drawing are available from Ground Support Equipment Department, Naval Air Engineering Center, Philadelphia, PA 19112.)

PUBLICATIONS

NAVSEA

0910-LP-003-9770 - Navy Installation and Maintenance Book

(NIMB), CD-ROM volume S9086-CH-STM-010 - Naval Ships Technical Manual

• Chapter 300, Elect r ic Plant/General

• Chapter 074, Welding and Allied Processes.

(Copies of above publications are availa ble from the Standardization Documents Order Desk, Bldg. 4D, 700 Robbins Avenue, Philadelphia, PA 19111-5094.)

2.2 Non-Government publications . The following documents form a part of this document to the extent specified herein. Unless otherwise specified, the issues of the documents which are DoD adopted are those listed in the issue of the DoDISS cited in the solicitation. Unless o therwise specified, the issues of documents not listed in the DoDISS are the issues of the documents cited in the solicitation (see 6.2).

AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM)

A 666 - Standard Specification for Austenitic Stainless

Steel, Sheet, Strip, Plate, and Flat Bar (DoD adopted)

A 312 - Standard Specification for Austenitic Stainless Steel Pipe

A 580 - Standard Specification for Austenitic Stainless Steel

B 152 - Standard Specification for Copper Sheet, Strip, Plate, and Rolled Bar. (DoD adopted)

(Application for copies should be addressed to the American Society for Testing and Materials, 1916 Race Street, Philadelphia, PA 19103.)

NATIONAL FIRE PROTECTION ASSOCIATION (NFPA)

National Electrical Code Handbook

(Application for copies should be addressed to the National Fire Protection Association, One Batterymarch Park, P. O. Box 9101, Quincy, MA 02269-9101.)

(Non-Government standards and other publi cations are normally available from the organizations that prepare or distrib ute the documents. These documents also may be available in or through libraries or other informational services.

2.3 Order of precedence . In the event of a conflict between the text of this document and the references cited herein, the text of t his document takes precedence.

Nothing in this document, howe ver, supersedes applicable laws and regulations unless a specific exemption has been obtained. Where conflicts exist between the require-ments of this document and other publications, specifications, standards, or dra wings, NAVSEA should be notified.

3. DEFINITIONS

3.1 Acronyms used in this standard . The acronyms used in this standard are defined as follows:

AGC - Automatic gain control ASTM - American Society for Testing and Materials AVC - Automatic volume control BBN - Broadband noise CID - Commercial item description COTS - Commercial-off-the-shelf CRES - Corrosion-resistant steel DC - Direct current DoD - Department of Defense DoDISS - Department of Defense Index of Specifications and Standards E - Electromagnetic environmental effects3

EM - Electromagnetic EMC - Electromagnetic compatibility EME - Electromagnetic environment EMI - Electromagnetic interference EMP - Electromagnetic pulse HF - High frequency ICD - Installation control drawing IEMC - Industrial electromagnetic compatibility IMI - Intermodulation interference IOIC - Integrated Operational Intelligence Center LF - Low frequency MF - Medium frequency MHz - Megahertz NAEC - Naval Air Engineering Center NAVSEA - Naval Sea Systems Command NDI - Non-developmental item NFPA - National Fire Protection Association NSTM - Naval Ships Technical Manual NTDS - Naval Tactical Data System PCI - Pulse current injection RAM - Radar absorbent material RF - Radio frequency SCI - Signal current injection SDO - Standards development organization SE - Shielding effectiveness SSS - System Safety Society TDB - Test Documentation Booklet TPD - Terminal protection device TSTP - Total Ship Test Program TSTRs - Total Ship Test Requirements UHF - Ultrahigh frequency UL - Underwriters Laboratories VDE - Verbad Deutscher Elektrotechniker (German Institute of Electrical

Engineers) VHF - Very high frequency Z - Impedance

3.2 Bond-Bonding (electrical) . An electrical bond is a conductive (electrical current) path between two metallic surfaces established by welding, bolting/clamping, or addition of a bond strap. Bonding is the act of creating the bond.

3.3 Bond classification . The electrical bonding methods specified herein are classified as follows:

Class A - Metallic surfaces bonded by welding or brazing.

Class B - Metallic surfaces bonded by bolting or clamping.

Class C - Metallic surfaces bonded by bridging them with a metallic (conductive) bond strap.

3.4 Bond strap . A device used to establish a class C bond. Bond straps are classified, according to construction, into four types:

Type I - CRES 316 1/4-inch wire rope with lugs of CRES 316L SCHED 80S pipe.

(Note: Separately acquired mou nting bosses are required to install Type I bond straps.)

Type II - Flat CRES 316 with mounting holes in each end.

Type III - Flat copper with mounting holes in each end.

Type IV - Flat copper braid with mounting holes in each end.

3.5 Bright metal . The cleaning of any paint, grease, rust, corrosion or other foreign material from a metal surface thereby exposing the basic metal in a clean or bright condition.

3.6 Broadband noise (BBN) . EM interference that has the spectral energy distributed over a wide frequency in relation to the frequency bandwidth of the equipment receiving the interference. Broadband noise interference is broadly t unable and will exist over all or a portion of the tuning range of an affected receiver.

3.7 Commercial-off-the-shelf (COTS) . COTS equipment is any item that can be purch ased through commercial retail or wholesale distributors as is, for example;

equipment that is available as a catalog item.

3.8 Computer ground system . A separate hardwired ground system installed in accor dance with DoD-STD-1399-406 to isolate the power supplies of shipboard digital systems such as the Navy Tactical Data System (NTDS) and Integrated Operational Intelligence Center (IOIC) from EMI and power line transients generated in other elec-trically-powered systems on board (see Electrical surge suppressor).

3.9 Conduit . Conduit is a metal enclosure, normally of circular construction, used as EM shielding for a cable or cables routed within the conduit. Conduit may be rigid or flexible. Flexible conduit used to satisfy requirements of this document shall be in accordance with MIL-C-24758.

3.10 Electrical surge suppressor, marine type . A power line conditioning device to protect vulnerable electronic equipment from common mode and normal mode voltage and c urrent transients generated in other electrically-powered on board systems sharing electrical power lines (as opposed to a separate power line/ground system per

3.8 above).

3.11 Electromagnetic compatibility (EMC) . The ability of electronic/electrical equipment, subsystem and systems to operate in their intended operational enviro nments without suffering or causing unacceptable degradation because of EM radiation or response.

3.12 Elect romagnetic environmental effects (EME) . The resulting product of the power and time distribution, in various frequency ranges, of the radiated or con ducted EM emission levels that may be encountered by a military force, system or platform when performing its assigned mission in its intended operational environment.

3.13 Electromagnetic interference (EMI) . EMI is EM energy which interferes with the detection and analysis of a desired signal, or which causes an equipment malfunction.

3.14 Electromagnetic pulse (EMP) . A short duration, high intensity pulse resulting from the detonation of a nuclear device in the exosphere.

3.15 Ground (ground potential) . A point, plane, or surface designated as the zero potential (nominally) common r eference point for electrical or electronic equipment.

3.16 Ground loop . More than one path to ground for an equipment or system such that desig nated ground is not maintained at a common (zero voltage) potential;

norma lly caused by multipoint grounding. Lack of a common reference point (ground) results in common mode (interference) currents in the ground loop.

3.17 Ground, personnel safety . Bonding of electrical and electronic equipment cabinets, cases, housings and exposed metal (conductive) components to ground potential by any class bond described herein, or by the installation of a ground wire to establish a contact resistance of 0.1 ohm or less.

3.18 Ground, radio frequency (RF) . Unless otherwise specified, is the ground established in a class A, B, or C bond.

3.19 Ground, 360 degrees (peripheral) . A continuous meta l-to-metal bond, existing or provided, around the outer perimeter of a metallic item or cable shield termi nating at or penetrating through a metal surface that is at ground potential.

3.20 Grounding . The process of bonding a metallic item to ground potential.

3.21 Intermodulation interference (IMI) . The production in a nonlinear element of frequencies equal to the sums and differences of int egral multiples of two or more frequency sources which cause EMI in another equipment or system. The nonlinear element may be internal or external to electronic systems.

3.22 Maintenance-related EMI . A designation assigned to EMI problems that can have severe, medium or mild mission area impact, but have been proven to result from improper installation or inade quate maintenance. Proper installation and continuing maintenance will prevent maintenance-related EMI from affecting operations.

3.23 Mobile-transportable electrical equipment . Mobile-transportable electrical equipment is any equipment that: (a) can be moved from place-to-place for use, (b) (normally) remains stationary while in use, and (c) is powered by a plug-in power cord versus being hard-wired to the electrical supply.

3.24 Nonlinear junction . A contact area between two metallic surfaces which exhib its nonlinear voltage-current transfer characteristics when subjected to an RF volta ge. This nonlinearity is usually caused by corrosion or other semi-conducting materials in the contact area.

3.25 Non-developmental item (NDI) . NDI equipment is any item not requiring develo pment. NDI can be COTS, ruggedized, or militarized. NDI may include any of the items specified in a through d:

a. An item of supply that is available in the commercial marketplace.

b. A previously developed item of supply that is in use by a department or agency of the United States Government, a state or local gover nment, or a foreign government with which the United States has a mutual defense cooperation agreement.

c. An item described in a or b above that requires only minor modification to conform to the procuring agency's requirements.

d. An item currently being produced that does not conform to requirements specified in a through c above solely because the item is not yet in use, or not yet available in the commercial marketplace.

3.26 Non-topside areas . Areas inside the hull or superst ructure of a ship, a deck mounted shelter, or an enclosure not exposed to weather.

3.27 Portable equipment . Portable equipment is any equipment easily moved from place-to-place for use and (no rmally) capable of being hand-held while in operation.

3.28 Shield . A metal barrier of solid, screen, or braid construction used to protect electronic components, wires, or cables from EM energy; or used to reduce the emission of EM energy from components, wires, or cabling.

3.29 Shielded area . Area not di rectly exposed to EM energy. This includes areas inside the hull and superstructure of metallic hull ships; areas inside metallic shel ters, a metallic enclosure or a metallic mast; and areas in screen rooms on nonmetallic hull ships.

3.30 Terminal protection device (TPD) . A quick reaction switching device which is installed between a susceptible circuit and ground to protect electronic comp onents from lightning and EMP damage. TPDs may also be identified as transient protection devices or surge protection devices.

3.31 Topside areas . All shipboard areas continuously exp osed to the weather, such as the main deck and above, catwalks, well decks, and those exposed portions of gallery decks.

3.32 Trunk, wireway . A metal enclosure that provides EM shielding to the cables routed therein. One or more sides of the trunk may be ship's structure.

4. GENERAL REQUIREMENTS

4.1 Performance requirements . The following shipboard EMI control bonding, grounding, and other techniques for EMC and safety shall be installed or implemented and maintained as necessary for optimized electrical and electronic system perfo rmance and safe operation.

4.1.1 Grounding; ship's ground potential . On both metallic and nonmetallic hull ships, ground potential shall be established and maintained in accordance with 5.1.1 as required for electrical and electronic equipment operation, EMC, and electrical safety grounding.

4.1.1.1 Common reference ground plane . Any metallic item, such as; sheet metal, flat stock, stranded or solid conductor cable, etc., that is class A bonded (welded or brazed) to ground potential in accordance with 5.1.2 shall be designated as an element of the ship's ground plane.

4.1.1.2 Class B and class C bonding and grounding for EMC . Electrical and electronic equipment shall be class B or class C bonded to the ground plane. Minimum direct current (DC) resistance and RF impedance (Z) shall be established across all class B and class C bonding and grounding junctions.

4.1.1.2.1 Metal-to-metal contact at bonded junction(s) . Metal-to-metal contact at all class B and class C bond mating surfaces shall be established as required to attain and maintain minimum DC resistance and RF impedance, as follows:

a. DC resistance . The DC resistance across bonding and grounding junctions shall not exceed 0.1 ohm for electrical safety.

b. RF Impedance . The RF impedance across bonding and grounding junction(s) shall not exceed 25 ohms at 30 megahertz (MHz) (see 6.4).

4.1.1.2.2 Preser vation of bolted mating surfaces . All metallic mating surfaces that are bolted together to form a class B or class C bond shall be sealed and preserved to prevent contamination and deterioration from environmental factors, such as; s eawater, salt air, stack gas, etc., and to maintain bond effectiveness between scheduled maintenance availabilities.

a. Installing activities option . Unless the procedure to be used is specified in an installation control dra wing (ICD) or other directive, surface preparation and preservation procedures used to meet 4.1.1.2.1a and 4.1.1.2.1b (above) shall be at the option of the installing activity.

b. Advancing technology . Introduction of advancing technology and innovation in the areas of shipboard system installation, corrosion control procedures and preservation materials is encouraged.

c. Appendix A . Appendix A provides guidelines and suggested procedures which may be used for surface preparation, installation and preservation.

4.1.1.2.3 Bond strap installation . Bond straps shall be installed using methods that permit inspection and removal and reinstallation or replacement when required.

They shall be installed such that: vibration, expansion, contraction, or relative movement incident to normal service shall not break or loosen the bond strap connection.

a. Topside installation . Type I and II bond straps only shall be installed topside.

b. Below decks installation . Type III and IV bond straps shall be installed in below decks locations.

c. Structural integrity and motion . Installations of bond straps shall not affect the integrity of equipment cases, cabinets or enclosures. They shall not:

(1) Weaken any structure or item to which a bond strap is attached, or

(2) Restrict the movement of any hinged or movable item.

d. Mounting s tuds, bolts and holes . When available and in good condition, exist ing studs, bolts, or threaded holes shall be used for Type II, III and IV bond strap installation.

4.1.2 Hull-ge nerated EMI . To prevent harmful EMI caused by nonlinear or intermittent metal-to-metal co ntact junctions in the topside EME, the ship's topside areas shall be, as nearly as possible, a single conducting surface free of all p inned, snap-linked, chain-linked, or other metallic discontinuities that might act as sourc e(s) of IMI and BBN. Hull-generated EMI control measures shall be implemented in accordance with the general control requirements listed below and the detailed requirements specified in 5.2.

a. Metal-to-metal contact junc tions in the topside EME should be avoided by use of nonmetallic substitutes when available.

b. Metal-to-metal contact junctions, where movability or removability is not a requirement, should be class A bonded.

c. Metal-to-metal contact junctions, where movability or removability is a requi rement, should be class B or class C bonded to provide a low impedance current path around the junction.

d. The joining of dissimilar m etals by bolting or riveting should be avoided in topside areas.

e. Except for anchor and anchor holding, metal chain shall not be installed in topside areas.

f. Loose metallic items, such as pipes, cables, and portable rigging should not be stowed, stacked, or lashed down in topside areas.

4.1.3 Hull and cable penetration EMI . Harmful EM radiations intruding past shielding boundaries established by the hull, shielded compartments, and cable s hields shall be prevented in accordance with 5.3

4.1.3.1 Cable shi elding . EM shielding for cables that must be routed in ship topside areas exposed to EM en ergy shall be provided by routing them within: (a) the metal lic mast, (b) the skin of the ship, or (c) a metal enclosure such as a wireway trunk or conduit until within the skin of the ship.

4.1.3.2 Hull penetrations . Cables, conduit, waveg uide and pipes penetrating the hull (or s hielded compartments) shall be treated to prevent topside EME energy intrusion (hull penetration EMI) through the skin of the ship into below decks spaces and equipment.

4.1.4 Superstructure blockage and reflections . Mast/superstructure construction practices and materials shall be implemented in general compliance with 5.4 as required to prevent harmful re flections, false target generation and degraded system performance resulting from antenna-structure coupling.

4.1.5 Equipment-generated EMI prevention .

4.1.5.1 Equipment-generated IMI . Low frequency (LF), medium frequency (MF), high frequency (HF), very high frequency (VHF), and ultrahigh frequency (UHF) receiving equipment should be connected to associated antennas via protective devices in g eneral conformance with 5.5 to preclude equipment-generated IMI.

4.1.5.2 BBN suppression; portable electrical tools . Arc suppression filters shall be provided across the commutator/brushes of all electric motor-driven tools.

4.1.6 Electr ical safety; personnel shock hazard prevention . Electrical and electronic equipment operated from an external electrical power source of 30 volts or more shall be grounded to provide electrical shock hazard protection integral to the equipment (see 5.6 and Appendix B).

4.2 Performance demonstration . Effective shipboard bonding, grounding and other techniques for EMC and safety shall be demonstrated in accordance with the testing requirements of the NAVSEA Total Ship Test Program (TSTP) and the inspections and tests spe cified in the construction Test Documentation Booklet (TDB) or the avail-ability Total Ship Test Requirements (TSTRs) list.

4.2.1 Ground plane and hull-generated EMI control . Effectiveness of the ship's ground p lane and effective IMI and BBN control shall be demonstrated in accordance with visual inspections and system readiness, IMI/BBN r ecognition and discovery tests when specified in the TDB/TSTRs list.

4.2.2 Hull- penetration EMI . Effective hull-penetration EMI control shall be demonstrated in accordance with Pulse Current Injection (PCI) or Signal Current Injection (SCI) test(s) when specified in the TDB/TSTRs list.

4.2.3 Cable and case penetration/radiation EMI . Effec tive cable/case penetration and radiation EMI control shall be demonstrated in accordance with system visual inspections, EMI recognition and discovery test(s) when specified in the TDB/TSTRs list.

4.2.4 Superstructure blockage/reflections, EM signature reduction . Effective superst ructure blockage/reflections control and EM signature reduction shall be demonstrated in accordance with a topside visual inspection and system readiness and discovery testing when specified in the TDB/TSTRs list.

4.2.5 Equipment-generated IMI prevention . Effectiveness of the narrowband filters, tuning circuitry and multicouplers for prevent ion of equipment-generated IMI shall be demonstrated in the course of the IMI recognition and source location t est(s) when specified in the TDB/TSTRs list.

4.2.6 Electrical safety ground . Effective electrical safety grounding shall be demonstrated in accordance with visual inspection(s), continuity, and other elec trical safety test(s) when specified in the TDB/TSTRs list.

5. DETAILED REQUIREMENTS

5.1 Ground potential and ship's ground plane(s) .

5.1.1 Ground potential .

5.1.1.1 Ground potential for metallic hull ships . On metallic hull ships, the metal hull, when in contact with the water, shall establish and be designated as ground potential.

5.1.1.2 Ground potential for nonmetallic hull ships . On nonmetallic hull ships, ground plate(s), installed to provide an earth ground c onnection via contact with sea water, shall be installed to establish ground potential.

5.1.1.2.1 Ground plate location . On nonmetallic hull ships, the ground plate(s) shall be installed at the lowest point of the structural hull, as close as possible to the vertical of the mast.

5.1.1.2.2 Connection of the cable ground system . A throughbolt shall be brazed to each ground plate to provide a connection point for ins tallation of the cable ground-ing system ground plane (see Appendix C).

5.1.2 Ground plane(s) . For both metallic and nonmetallic hull ships, all class A bonded (welded or brazed) ex tensions to ship's ground potential, topside and below decks, shall be designated as the ship's ground plane.

5.1.2.1 Elements of the ground plane . The following should be class A bonded to ground potential to form elements of the ground plane.

5.1.2.1.1 Superstructure, equipment foundations and racks . Metallic superstruc-ture, equipment foundations and racks (not shock mounted), and mounting studs or brackets to which equipment is bolted for installation should be class A bonded to ground potential.

5.1.2.1.2 Cable grounding system's branches . Cable grounding system's branches and branch extensions connected to or terminating at the gr ound plate(s) of a nonmetallic hull s hip's ground plane (see 5.1.1.2.2 above) should be class A bonded to ground potential.

5.1.2.1.3 Shielded room(s) . Shielded room(s) on non metallic hull ship's should be class A bonded to the ground plate(s) via the cable ground system, as necessary, to maintain the shielding boundaries at ground potential.

5.1.2.1.4 Computer ground system . Installation of a separate computer ground system in accordance with DoD-STD-1399-406 should be specified for hard-wired shipb oard digital computer equipment to isolate the power supplies of major digital systems such as the Navy Tactical Data System (NTDS) and Integrated Operational Intelligence Center (IOIC) from other electrically-powered systems on board.

5.1.2.2 Grounded items . Equipment and hardware that is class B or class C bonded to the ship's ground plane (see 5.1.3) shall be designated as grounded, but not as an element of the ground plane for grounding other items.

a. Stacked (c ascaded) grounding . Items that are class B or class C bonded to the ground plane (i.e.; grounded) shall not be used as a tie point to ground pot ential (i.e.; the ground plane) for subsequent items.

b. Bond strap and grounding wire routing . All bond straps and grounding wires bonded to the ground plane shall be directly routed and as short as practical.

5.1.2.2.1 Equip ment cabinets and hardware items . Electrical and electronic equip ment cases, cabinets or enclosures that may require routine removal for repair and r eplacement during the ship's life cycle should be class B or class C bonded to ground.

5.1.2.2.2 Shoc k-mounted . Shock-mounted equipment and equipment racks, and equipment mounted therein, should be class B or class C bonded to ground.

5.1.2.2.3 Large/long hardware items . Unless insulated to prevent metal-to-metal contact in accordance with 5.2.3 (below), topside metallic hardware items with any physi cal dimension greater than approximately 3 meters or 10 feet should be class B or class C bonded to ground.

5.1.3 Class B and class C bonding and grounding .

5.1.3.1 Class B and C bond installation . All class B and C bonding is dependent on esta blishing and maintaining low resistance, low RF impedance, metal-to-metal contact junction(s) between the items to be bonded by b olting or clamping as required for safe system operations and EMC.

a. Unless otherwise specified, the method by which the metal-to-metal contact surfaces are prepared and whet her the junction is bolted or clamped is at the option of the installing activity.

b. Appendix A provides various methods and materials that can be used to prepare the metal-to-metal contact surfaces for bonding, and to seal and preserve the junctions to retard subsequent contamination and corrosion.

c. Class B and C bond installations shall meet all specified safety and E 3 inspection and test requirements.

5.1.3.2 Hardware for class B and C bonding . All h ardware (e.g.; straps, bosses, bolts, nuts, and washers) used for new or replacement s hipboard class C bonding shall conform to MIL-DTL-24749 requirements. Unless otherwise specified in an installation control d rawing (ICD), hardware for equipment and metallic items requiring class B bonding also shall conform to that specified in MIL-DTL-24749.

5.1.3.3 Class C bond straps . Class C bond strap requirements shall be docu mented in an EM Control Topside Arrangement drawing as specified in the applicable drawing development or revision procedure.

a. Excess or unnecessary bond straps shall not be installed.

b. Unless removal and reinstallation is required in the course of production, still functional bond straps fabricated from TRXF-84 copper (welding cable) wire, copper-nickel (CuNi) alloy str aps, and other previously approved materials shall not be removed or replaced.

c. When removal and reinstallation is required in the c ourse of production, bond straps fabricated from previou sly approved materials shall be replaced with hardware conforming to MIL-DTL-24749.

d. Equipment cases, cabinets and enclosures shall not be damaged or altered for bond strap installation. Holes shall not be drilled into and boss(es) shall not be welded to, an equipment case, cabinet or enclosure.

(1) Factory-installed grounding studs, bolts, or threaded holes shall be used as the bond strap tie-point to the equipment (when available).

(2) When a factory-installed tie point is not available, the bond strap end-lug shall be bolted to the equipment at pre-drilled holes in the mounting surface(s).

5.1.3.3.1 Type I bond strap . Type I bond straps shall be used in shipboard t opside areas when appropriate to bonding metal-to-metal junctions identified as hull-generated EMI sources.

5.1.3.3.2 Type II bond strap . Type II bond straps shall be used in shipboard topside areas for bonding EMI source items such as antenna tuners or couplers, equipments, enclosures, and cabinets.

5.1.3.3.3 Type III bond strap . Type III bond straps shall be used in shipboard non-topside areas for bonding equipments, enclosures, and cabinets.

5.1.3.3.4 Type IV bond strap . Type IV bond straps s hall be used in shipboard non-topside areas for bonding equipment utilizing sound isolated mounts or shock mounts (nonmetallic mounts).

5.2 Hull -generated EMI prevention . Hull-generated EMI, caused by topside nonli near or intermittent metal-to-metal contact junctions as a result of EM energy induced as nearby antennas are radiated, shall be prevented through:

a. Nonmetallic material

b. Topside stowage practices

c. Insulation material

d. Bonding and grounding

5.2.1 Nonmetallic topside material . A nonmetallic substitute should be used to eliminate (at least one of) the metal item(s) that make up topside metal-to-metal contact junction(s).

a. Implementation of advancing technology . To eliminate metal-to-metal contact junct ions in the shipboard topside EME, incorporation of state-of-the-art composite and nonmetallic materials, implementation of advancing technology, related fabri cation practices and installation procedures is encouraged.

b. Performance requirements . New materials and advancing technology introduced in ships shall meet all contract performance specifications.

c. Nonmetallic substitutes and fabrication practices . Nonmetallic items and fabrication practices to be co nsidered include but are not limited to the following:

(1) Fiberglass or composite stowage lockers and racks, portable-removable stanchions, flagstaffs and jackstaffs.

(2) Hybrid ladder assemblies, i.e.; fiberglass or composite siderails - metal treads and handrail(s).

(3) Fiberglass or com posite (double-insulated) equipment cabinets and motor casings.

(4) Aramid fiber (KEV LAR®) rope lifelines, mast stays, standing rigging and safety nets.

5.2.2 Topside stowage . Stowage brackets, lockers, bins, or other stowage pro-tected f rom the topside EME, shall be provided for portable and removable hardware used topside, such as: awning stanchions, flag and jack staffs, accommodation ladders;

wire rope slings, gripes, and stays, and tie-down chains/chocks when not in use. Deck stowage for metallic material not required for use topside should be avoided.

5.2.2.1 Portable and removable metallic deck hardware . Portable and removable metallic deck hardware items should be stowed when not in use on; sponson decks, inside covered companionways, below decks, or in stowage lockers and other protected areas isolated from HF transmitter antennas.

5.2.2.2 Other metallic ma terial . Metallic items carried for stock, turn-in, or repair and not requiring immediate access, such as; angle iron, I-beams, pipes, sheet metal, barrels, argon-oxygen-nitrogen gas bottles, expended ordnance shell casings, etc., shall not be stowed topside near EM antennas.

5.2.3 Insulate topside metal-to-metal contact junctions . Unless isolating the item from ground will result in its becoming an RF burn hazard, insulating material shall be installed on the cont act surfaces of built-in stowage brackets for metallic hardware items located in the topside EME whenever:

a. A suitable nonmetallic substitute is not available,

b. The items, such as; booms, dismountable highline sta nchions and their stowage cradles, cannot be relocated from the topside EME, and

c. Insulation is preferable to, or the item is not suited to bonding.

5.2.4 Bond topside metal-to-m etal contact junctions . Whenever metallic hardware in the topside EME is identified as a hull-generated EMI source, and the EMI is not resolved in accordance with 5.2.1, 5.2.2 or 5.2.3 (abov e), the metal-to-metal contact junction shall be class A, B, or C bonded in accordance with 5.1.2 and 5.1.3 as required to eliminate IMI/BBN.

a. Class A bonding recommended . Stationary metallic hardware items commonly installed topside, such as; li ferails, stanchions, swab racks, etc., should be class A bonded.

b. Class B or C bonding recommended . Portable and removable hardware items commonly installed topside, such as; equipment cabinets, enclosures, and cases, dismountable lifeline and heavy weather stanchions, flagstaffs and jackstaffs, etc., should be class B or C bonded.

c. Bonding not recommended . Bonding is not a suitable alternative for hull-generated EMI control when bon ding of the IMI/BBN source junction(s) will prevent or impede physical or mechanical operation or functional use of the item(s).

(1) Emergency equipment . Emergency equipment shall not be bonded when unbolting or removal of a bond strap will delay access or prevent use.

(2) Moving hardware . Moving hardware items shall not be bonded when doing so will prevent operation over the item's full range of travel or rotation.

(3) Quick-release fittings . When installation of a bond strap will delay operation of quick-release fittings, such as those used with; lifeline assemblies, jetti ssonable fuel and ordnance storage racks and lockers, pelican hooks, etc., the item shall not be bonded.

5.3 Cable and hull penetration EMI control .

5.3.1 Topside cable installations . All electrical and electronic system cables routed outside the skin of the ship, where subject to illumination by high power EM energy, shall be EM shielded (or otherwise treated) to prevent coupling of own-ship's EM transmissions via the cable's conductors and shields. This EM shielding (or other treat ment) is intended to minimize the inter-system transfer of electromagnetic energy, particularly to below deck items.

5.3.1.1 Shielded cable . Coaxial cables and other cables with inherent overall shielding shall be grounded at the:

a. Cable end terminations . Shielded cables shall be fabricated using the appropriate coaxial connector(s) or connector EMI backs hells to bond the cable shield 360 degrees at each end.

b. Hull penetration point . Shielded cables should be 360-degree bonded at…