EDE SIR Attachment J.7 FAA-STD-019e Lightning and Surge Protection.pdf

FAA-STD-019e December 22, 2005

DEPARTMENT OF TRANSPORTATION

FEDERAL AVIATION ADMINISTRATION STANDARD

LIGHTNING AND SURGE PROTECTION,

GROUNDING, BONDING AND SHIELDING

REQUIREMENTS FOR FACILITIES AND

ELECTRONIC EQUIPMENT

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This Page Intentionally Left Blank iii

FOREWORD

All construction of Federal Aviation Administration (FAA) operational facilities and the electronic equipment installed therein shall conform to this standard. This document defines minimum requirements for all FAA facilities. When the specific needs of a facility exceed these minimum requirements, the facility shall be designed and installed to meet these specific needs.

These needs are influenced by the equipment to be installed at the site, the configuration of the structures and location of the equipment, and by the physical environment present at the location.

The requirements contained in this document reflect investigation and resolution of malfunctions and failures experienced at field locations. The requirements thus are considered the minimum necessary to harden sites sufficiently for the FAA missions – to prevent delay or loss of service, to minimize or preclude outages, and to enhance personnel safety. Further, the requirements in the document have been coordinated with industry standards, and in some cases exceed industry standards where necessary to meet the FAA missions.

In this document the use of “shall” or verbs such as “construct”, “weld”, “connect”, etc indicates a requirement necessitating mandatory compliance. In cases when implementation of certain requirements is not technically feasible, a National Airspace System (NAS) Change Proposal (NCP) must be submitted with adequate justification and technical documentation and approved by the NAS Configuration Control Board (CCB) before a deviation is permitted.

This document is organized in accordance with MIL-STD-962D.

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1 SCOPE

1.1 Scope

1.2 Purpose

2 APPLICABLE DOCUMENTS

2.1 Government Documents

2.2 Non-Government Documents

3 DEFINITIONS

3.1 Access Well

3.2 Air Terminal

3.3 Armored Cable

3.4 Arrester

3.5 Bond

3.6 Bond, Direct

3.7 Bond, Indirect

3.8 Bonding

3.9 Bonding Jumper

3.10 Branch Circuit

3.11 Building

3.12 Bulkhead Plate

3.13 Cabinet

3.14 Cable

3.14.1 Cable, AC (not the same as armored (DEB) cable)

3.14.2 Cable, Armored Direct Earth Burial (DEB)

3.14.3 Cable, Axial

3.14.4 Cable, Shielded

3.15 Case

3.16 Catenary Wire

3.17 Chassis

3.18 Clamp Voltage

3.19 Conductor, Bare

3.20 Conductor, Insulated

3.21 Conductor, Lightning Bonding (Secondary)

3.22 Conductor, Lightning Down

3.23 Conductor, Lightning Main

3.24 Conductor, Lightning Roof

3.25 Crowbar

3.26 Earth Electrode System (EES)

3.27 Electromagnetic Interference (EMI)

3.28 Electronic Multipoint Ground System

3.29 Electronic Single Point Ground (SPG) System

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3.30 Enclosed Ferrous Cable Tray

3.31 Equipment Areas

3.32 Equipment Grounding Conductor

3.33 Equipment

3.34 Facility Ground System

3.35 Faraday Cage

3.36 Feeder

3.37 Ferrous Conduit

3.38 Fitting, High Compression

3.39 Ground

3.40 Grounded Conductor

3.41 Grounded

3.42 Grounding Conductor

3.43 Grounding Electrode

3.44 Grounding Electrode Conductor

3.45 High frequency

3.46 Horizontal Transitions

3.47 Jordan Dissipation Plate Design

3.48 Landline

3.49 Line Replaceable Unit

3.50 Low Frequency

3.51 Main Service Disconnect

3.52 National Electrical Code

3.53 Operational Areas

3.54 OPR

3.55 Overshoot Voltage

3.56 Pressure Connector

3.57 Rack

3.58 Reference Plane or Point, Electronic Signal (Signal Ground)

3.59 Rigid Metal Conduit (RMC)

3.60 RGS

3.61 Shield

3.62 Signal

3.63 Standard Version

3.64 Structure

3.65 Surge

3.66 Susceptibility Level

3.67 Transient

3.68 Transient Suppressor

3.69 Turn-on Voltage

3.70 Zone of Protection

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4 GENERAL REQUIREMENTS

4.1 Requirements Common to Both Facilities and Equipment

4.1.1 Bonding Requirements

4.1.2 Shielding Requirements

4.1.3 Electrostatic Discharge (ESD) Requirements

4.1.4 Electromagnetic Compatibility Requirements

4.2 Facility Requirements

4.2.1 Passive Transient Protection Requirements

4.2.2 Active Transient Protection Requirements

4.2.3 Lightning Protection System Requirements

4.2.4 Earth Electrode System (EES) Requirements

4.2.5 Main and Supplemental Ground Plates

4.2.6 General Grounding and Bonding Requirements

4.2.7 Signal Reference Structures Requirements

4.2.8 Electronic Single Point Ground System Requirements

4.2.9 DC Bus Grounding Requirements

4.2.10 National Electrical Code (NEC) Grounding Compliance

4.2.11 Airport Traffic Control Towers (ATCT) Special Requirements

4.3 Equipment Requirements

4.3.1 Electronic Signal Lines and Cables

4.3.2 Signal Control and Data Line Entrance

4.3.3 Power Entrance

4.3.4 Electronic Equipment Grounding

4.3.5 Equipment Signal Grounding Requirements

4.3.6 Equipment Shielding Requirements

4.3.7 Circuit and Equipment ESD Design Requirements

5 DETAILED REQUIREMENTS

6 NOTES

6.1 Acronyms and Abbreviations

6.2 Guidelines

6.3 Version Cross-Reference

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List of Figures

Figure I. Order of Assembly for Bolted Connections Figure II. Bonding of Connectors to Mounting Surface Figure III. Grounding of Overall Cable Shields to Connectors and Penetrating Walls Figure IV. Grounding of Overall Cable Shield to Terminal Strip Figure V. Lightning Protection for Radomes and Radar Antenna Platforms Figure VI Common Collective Area of Increased Risk Figure VII. Fence Grounding Figure VIII. Grounding Fences Requiring an EES Figure IX. Grounding Trench Detail Figure X. Jordan Dissipation Plate Design Figure XI. Facility Grounding System Figure XII. Multipoint Ground Conductor Size Determination Figure XIII. Electronic Single Point Ground System Installation Figure XIV. Bonding of Conduit and Grounding Conductor Figure XV. Airport Traffic Control Tower Levels Figure XVI. Lines and Cables Requiring Protection Figure XVII. Single Point Electronic Ground Bus Bar Installation in Rack or Cabinet

List of Tables

Table I. Mechanical Bonds Between Dissimilar Metals Table II. Torque Requirements for Bolted Bonds Table III. Minimum Separation Distance Between Signal and Power Conductors Table IV. Surge Current Lifetime Requirements Table V. Entrance, Feeder, and Branch Panels Slope Resistance Requirements Table VI. Protection Voltages at 3kA Table VII. SPD Lifetime Conducted Landline Transient Level Requirements Table VIII. Grounding Conductor Color Codes Table IX. Size of Electronic Multipoint Ground Interconnecting Conductors Table X. Equipment Power Entrance Slope Resistance Requirements Table XI. Protection Voltages at 3kA for the Equipment Power Entrance Table XII. Electronic Equipment Power Entrance SPD Requirements ix ε

1 SCOPE

1.1 Scope

This document mandates standard lightning protection, transient protection, grounding, bonding and shielding configurations and procedures and control of electrostatic discharge (ESD) for new facilities, modifications and upgrades to existing facilities, new equipment installations, and new electronic equipment used in the National Airspace Systems (NAS). It provides requirements for the design, construction, modification or evaluation of facilities and equipment. (It is recommended that the OPR of this document be contacted to obtain technical guidance on the applicability of the requirements to modifications, upgrades and new equipment installations in existing facilities.)

This document is not mandatory for programs that have been funded prior to the issue date of this document, nor is it mandatory for construction contracts associated with programs funded prior to the issue of the document. Application of this document is at the discretion of the user for programs that have been funded prior to the issue of the document. The Office of Primary Responsibility (OPR) can mandate the use of this document for programs started before the issue date of this document, if funding is provided.

The interface between contractor owned equipment or electronic equipment not used for operational purposes (administrative local area network (LAN), administrative telephone, etc.)

and the operational facility shall be in accordance with this document.

1.2 Purpose

The requirements of this standard provide a systematic approach to minimize electrical hazards to personnel, electromagnetic interference and damage to facilities and electronic equipment from lightning, transients, ESD, and power faults.

2 APPLICABLE DOCUMENTS

2.1 Government Documents

Due to the continuous updating of Government documents, the Contracting Officer and/or the Implementation Engineer must specify the version current at contract award or project design.

These documents form a part of this standard and are applicable to the extent specified elsewhere in this document. If conflicts occur between these documents and the contents of this standard, the contents of this standard provide the superseding requirements.

FAA Specifications

FAA-C-1217 Electrical Work, Interior FAA-G-2100 Electronic Equipment, General Requirements NAS-SS-1000 Functional and Performance Requirements for the National

Airspace Air Traffic Control Element

FAA Orders

Order 6950.19 Practices and Procedures for Lightning Protection, Grounding, Bonding and Shielding Implementation Order 6950.20 Fundamental Considerations of Lightning Protection, Grounding, Bonding and Shielding

(Copies of these specifications, standards, orders, and other applicable FAA documents may be obtained from the Contracting Officer issuing the invitation-for-bids or request-for-proposals.

Requests should fully identify material desired, i.e. specification, standard, amendment, drawing numbers and dates. Requests should cite the invitation-for-bids, request-for-proposals, the contract involved, or other use to be made of the requested material.)

Military Documents

MIL-HDBK-232 Revision A Red/Black Engineering-Installation Guidelines MIL-HDBK-237 Electromagnetic Compatibility Management Guide for

Platforms, Systems and Equipment MIL-HDBK-253 Guidance for the Design and Test of Systems Protected Against the Effects of Electromagnetic Energy DOD/MIL-HDBK-263 Electrostatic Discharge Control Handbook DOD-STD-1686 Electrostatic Discharge Control Program for Protection of

Electrical and Electronic Parts, Assemblies and Equipment (Excluding Electrically Initiated Explosive Devices)

MIL-HDBK-419 Grounding, Bonding, and Shielding for Electronic Equipment and Facilities

MIL-PRF-87893 Performance Specification, Workstations, Electrostatic Discharge Control

MIL-W-87893 Military Specification, Workstations, Electrostatic Discharge (ESD) Control

MIL-STD-461 The Control of Electromagnetic Interference Emissions and Susceptibility

MIL-STD-889 Dissimilar Metals MIL-STD-1686 Electrostatic Discharge Control Program for Protection of

Electrical and Electronic Parts, Assemblies, and Equipment (Excluding Electrically Initiated Explosive Devices)

NACSIM 5203 Guidelines for Facility Design and Red/Black Installation (Confidential Document)

Single copies of Military specifications, standards, and handbooks may be requested by mail or telephone from Document Automation and Production Service Customer Service, Standardization Documents Order Desk, 700 Robbins Avenue, Building 4D Philadelphia, PA 19111-5094 or via dodssp.daps.dla.mil. Not more than five items may be ordered on a single request; the Invitation for Bid or Contract Number should be cited where applicable. Only latest revisions (complete with latest amendments) are available; slash sheets must be individually requested. Request all items by document number.

2.2 Non-Government Documents

Due to the continuous updating of Non-Government documents, the Contracting Officer and/or the Implementation Engineer must specify the version current at contract award or project design unless a specific version is called out in the requirements of this standard. These documents form a part of this standard and are applicable to the extent specified herein. While this standard may exceed the requirements of the following documents, Nationally required practices shall always be performed as a minimum.

Electronic Industries Alliance (EIA)

EIA Standard EIA-625

Requirements for Handling Electrostatic-Discharge-Sensitive (ESDS) Devices

Requests for copies of EIA Standards should be addressed to Electronic Industries Alliance, Corporate Engineering Department, 2500 Wilson Boulevard, Arlington, VA 22201 or telephone 703 907-7500. www.eia.org

National Fire Protection Association (NFPA)

NFPA 70 National Electrical Code (NEC) NFPA 77 Static Electricity NFPA 780 Standard for the Installation of Lightning Protection Systems

Requests for copies of NFPA documents should be addressed to the National Fire Protection Association, One Batterymarch Park, Quincy MA 02269. www.nfpa.org

Underwriters Laboratories, Inc. (UL)

UL 96 Lightning Protection Components UL 96A Installation Requirements for Lightning Protection Systems UL 779 (ANSI-A148.1) Electrically Conductive Floorings UL 1449 Transient Voltage Surge Suppressors

Requests for copies of UL documents should be addressed to Global Engineering Documents, 1500 Inverness Way, East Englewood, CO 80112. Telephone 303 397-7945, 800 854-7179.

www.ul.com

Institute of Electrical and Electronic Engineers (IEEE)

ANSI/IEEE C62.41 Recommended Practice on Surge Voltages in Low Voltage AC

Power Circuits ANSI/IEEE C62.45 IEEE Guide on Surge Testing for Equipment Connected to Low-

Voltage AC Power Circuits ANSI/IEEE 1100 Recommended Practice for Powering and Grounding Sensitive

Electronic Equipment (Emerald Book)

Requests for copies of IEEE documents should be addressed to Institute of Electrical and Electronic Engineers, 445 Hoes Lane, P.O. Box 1331, Piscataway, NJ 08855-9916.

www.ieee.org

Electrostatic Discharge (ESD) Association Documents

ESD ADV53.1 ESD Protective Workstations ANSI/ESD S4.1 Worksurfaces – Resistance Measurements ANSI/ESD S7.1 Floor Materials, Characterization of Materials ANSI/ESD S8.1 Symbols – ESD Awareness ANSI/ESD S11.11 Surface Resistance Measurement of Static Dissipative Planar

Materials ANSI/ESD S20.20 Development of an Electrostatic Discharge Control Program for

Protection of Electrical and Electronic Parts, Assemblies and Equipment

ANSI/ESD STM5.1 Sensitivity Testing, Human Body Model (HBM), Component Level

ANSI/ESD STM12.1 Seating - Resistive Measurement ESD TR20.20 Development of an Electrostatic Discharge Control Program for

Protection of Electrical and Electronic Parts, Assemblies and Equipment – Handbook

Requests for copies of ESD Association documents should be addressed to the ESD Association, 7900 Turin Road, Bldg 3, Suite 2, Rome, NY 13440-2069. Telephone 315 339-6937.

www.esda.org

3 DEFINITIONS

3.1 Access Well

A covered opening in the earth using concrete, clay pipe or other wall material to provide access to an EES connection.

3.2 Air Terminal

That component of a lightning protection system specifically designed to accept lightning strikes.

3.3 Armored Cable

Power, signal, control or data cable having an overall armor or covering constructed of ferrous (steel) material that provides both structural protection and electromagnetic shielding for direct buried cables.

3.4 Arrester

Components, devices or circuits used to attenuate, suppress, limit, and/or divert adverse electrical (surge and transient) energy. The terms arrester, suppressor and protector are used interchangeably except that the term arrester is used herein for components, devices and circuits at the service disconnecting means.

3.5 Bond

The electrical connection between two metallic surfaces used to provide a low resistance path between them.

3.6 Bond, Direct

An electrical connection utilizing continuous metal-to-metal contact between the members being joined.

3.7 Bond, Indirect

An electrical connection employing an intermediate electrical conductor between the bonded members.

3.8 Bonding

The joining of metallic parts to form an electrically conductive path to assure electrical continuity and the capacity to conduct current imposed between the metallic parts.

3.9 Bonding Jumper

A conductor installed to assure electrical conductivity between metal parts required to be electrically connected.

3.10 Branch Circuit

The circuit conductors between the final overcurrent device protecting the circuit and the load served.

3.11 Building

The fixed or transportable structure which provides environmental protection.

3.12 Bulkhead Plate

A metallic plate located where conduits, conductor, waveguides etc first enter the facility. The bulkhead plate provides a central point for the grounding of conduits, conductors and waveguides entering the facility or structure.

3.13 Cabinet

An enclosure designed either for surface mounting or flush mounting and is provided with a frame, mat, or trim in which a swinging door or doors are or can be hung.

3.14 Cable

A fabricated assembly of one or more conductors in a single outer insulation. Types include axial, armored and shielded.

3.14.1 Cable, AC (not the same as armored (DEB) cable)

Type AC cable is a fabricated assembly of insulated conductors in a flexible metallic enclosure.

3.14.2 Cable, Armored Direct Earth Burial (DEB)

Cable with a ferrous shield designed to provide both physical and electromagnetic protection to the conductors.

3.14.3 Cable, Axial

Cable where all conductors are oriented on a single axis. Examples include coaxial, biaxial, and triaxial cables

3.14.4 Cable, Shielded

Cable with a metalized or braid shield to improve resistance to electromagnetic interference

(EMI).

3.15 Case

A protective housing for a unit or piece of electrical or electronic equipment.

3.16 Catenary Wire

A catenary lightning protection system consisting of one or more overhead ground wires and supporting masts.

3.17 Chassis

The metal structure that supports the electrical or electronic components which make up the unit or system.

3.18 Clamp Voltage

Clamp voltage is the voltage that appears across the SPD terminals when the suppressor is conducting a surge or transient current.

3.19 Conductor, Bare

An electrical conductor that has no covering or electrical insulation.

3.20 Conductor, Insulated

An electrical conductor encased within material of composition and thickness recognized by the NEC as electrical insulation.

3.21 Conductor, Lightning Bonding (Secondary)

An electrical conductor used to bond a metal object, within the zone of protection and subject to currents induced by lightning strikes, to the lightning protection system.

3.22 Conductor, Lightning Down

The down conductor serves as the path to the earth grounding system from the roof system of air terminals and roof conductors or from an overhead ground wire.

3.23 Conductor, Lightning Main

The main conductors are the conductors intended to carry lightning currents between air terminals and ground terminations. These can be the roof conductors interconnecting the air terminals on the roof, the conductor to connect a metal object on or above roof level that is subject to a direct lightning strike to the lightning protection system, or the down conductor.

3.24 Conductor, Lightning Roof

Roof conductors interconnecting all air terminals to form a two-way path to ground from the base of each air terminal.

3.25 Crowbar

The term “crowbar” refers to a method of shorting a surge, voltage, or current using surge protective devices.

3.26 Earth Electrode System (EES)

A network of electrically interconnected rods, plates, mats, piping, incidental electrodes (metallic tanks, etc.) or grids installed below grade to establish a low resistance contact with earth.

3.27 Electromagnetic Interference (EMI)

Any emitted, radiated, conducted or induced voltage which degrades, obstructs, or interrupts the desired performance of electronic equipment.

3.28 Electronic Multipoint Ground System

An electrically continuous network consisting of interconnected ground plates, equipment racks, cabinets, conduit junction boxes, raceways, duct work, pipes, copper grid system, building steel, and other non-current-carrying metal elements. It includes conductors, jumpers and straps that connect individual items of electronic equipment to the SRP or MPG system.

3.29 Electronic Single Point Ground (SPG) System

An SPG signal reference network provides a single point reference in the facility for equipment that requires single point grounding. It consists of conductors, plates and equipment terminals, all of which are isolated from any other grounding system except at the main ground plate.

3.30 Enclosed Ferrous Cable Tray

A cable tray with steel sides and bottom with a steel cover or lid. This tray may have small holes and gaps.

3.31 Equipment Areas

Areas that contain electronic equipment used to support NAS operation. These include electronic equipment rooms, TELCO rooms, VORs, Radars etc.

3.32 Equipment Grounding Conductor

The conductor with the phase and neutral conductors used to connect non-current-carrying metal parts of equipment, raceways, and other enclosures to the system grounded conductor and/or to the grounding electrode conductors at the main service disconnecting means or at the point of origin (Xo bond) of a separately derived system.

3.33 Equipment

A general term including materials, fittings, devices, appliances, fixtures, apparatus, machines, etc, used as a part of, or in connection with, an electrical installation.

3.34 Facility Ground System

Consists of the complete ground system at a facility including the EES , SRP or MPG system, electronic single point ground system (SPG), equipment grounding conductors, grounding electrode conductor(s), and lightning protection system.

3.35 Faraday Cage

A closed conducting surface, such as wire mesh, completely surrounding an object or person so as to protect from impinging electromagnetic waves.

3.36 Feeder

All circuit conductors between the service equipment or the source of a separately derived system and the final branch circuit overcurrent device.

3.37 Ferrous Conduit

Material composed of and/or containing iron. Rigid Galvanized Steel Conduit (RGS) thick walled threaded conduit (NEC Rigid Metal Conduit (RMC)). For the purpose of this document, conduits not adequate for magnetic shielding include Electrical Metallic Tubing (EMT), Intermediate Metal Conduit (IMC) and conduits made from silicon bronze and stainless steel.

3.38 Fitting, High Compression

See “Pressure Connector”.

3.39 Ground

A conducting connection, whether intentional or accidental, between an electrical circuit or equipment and the earth, or to some conducting body that serves in place of the earth.

3.40 Grounded Conductor

A system or circuit conductor that is intentionally grounded at the service disconnecting means or at the source of a separately derived system. This grounded conductor is the neutral conductor for the power system.

3.41 Grounded

Connected to earth through a connection of sufficiently low impedance and having sufficient current carrying capacity so that fault current which occurs cannot build up to voltages dangerous to personnel.

3.42 Grounding Conductor

A conductor used to connect equipment or the grounded circuit of a wiring system to the grounding electrode system. (In this standard, grounding conductors not related to or not used as part of NEC required electrical system grounding, are used for the electronic equipment grounding system).

3.43 Grounding Electrode

Copper rod, plate or wire embedded in the ground for the specific purpose of dissipating electric energy to the earth.

3.44 Grounding Electrode Conductor

The conductor used to connect the grounding electrode to the equipment grounding conductor and/or to the grounded (neutral) conductor of the facility at the service disconnecting means or at the source of a separately derived system.

3.45 High frequency

All electrical signals at frequencies greater than 100 kilohertz (kHz), and pulse and digital signals with rise and fall times of less than 10 µs are classified as high frequency signals.

3.46 Horizontal Transitions

Architectural term used to describe horizontal elements in a vertical structure (floors stair landings, etc.).

3.47 Jordan Dissipation Plate Design

Based on original design from W. Jordan FAA OKC.

3.48 Landline

Any conductor, line or cable installed externally above or below grade to interconnect electronic equipment in different facility structures or to interconnect externally mounted electronic equipment.

3.49 Line Replaceable Unit

Hardware elements whose design enables removal, replacement and checkout by organizational maintenance.

3.50 Low Frequency

Includes all voltages and currents, whether signal, control, or power, up to and including 100 kHz. Pulse and digital signals with rise and fall times of 10 µs or greater are considered to be low frequency signals.

3.51 Main Service Disconnect

Main Service Disconnect is a switch, fused switch or circuit breaker that disconnects main service AC power (generally utility power) from a facility. Also referred to as Service Disconnecting Means (SDM).

3.52 National Electrical Code

A standard containing provisions that govern the use of electrical wire, cable, equipment and fixtures installed in buildings.

3.53 Operational Areas

Areas used to provide NAS support such as IFR rooms, ARTCC control rooms, ATCT tower cabs and operations control centers.

3.54 OPR

OPR is an acronym for Office of Primary Responsibility. The OPR is assigned to maintain and interpret this standard.

3.55 Overshoot Voltage

The fast rising voltage that appears across transient suppressor terminals before the suppressor turns on (conducts current) and clamps the input voltage to a specified level.

3.56 Pressure Connector

For purpose of this document, “FAA approved pressure connectors” shall be those that use hydraulically crimped terminations to effect closure.

3.57 Rack

A frame in which one or more equipment units are mounted.

3.58 Reference Plane or Point, Electronic Signal (Signal Ground) The conductive terminal, wire, bus, plane, or network which serves as the relative zero potential for all associated electronic signals.

3.59 Rigid Metal Conduit (RMC)

A threadable raceway of circular cross section designed for the physical protection and routing of conductors and cables and for use as an equipment grounding conductor when installed with its integral or associated coupling and appropriate fittings.

3.60 RGS

See Ferrous Conduit.

3.61 Shield

A housing, shield, or cover which substantially reduces the coupling of electric and magnetic fields into or out of circuits or prevents accidental contact of objects or persons with parts or components operating at hazardous voltage levels.

3.62 Signal

Any electromagnetic transmission of information or control function. A signal can be analog, digital data or a control function such as a relay closure.

3.63 Standard Version

The applicable version of the standard is that issue in effect on the date of a contract signing.

3.64 Structure

Any fixed or transportable building, shelter, tower, or mast that is intended to house electrical or electronic equipment or otherwise support or function as an integral element of the air traffic control system.

3.65 Surge

An overvoltage or overcurrent of short duration occurring on a power line.

3.66 Susceptibility Level

The electronic equipment susceptibility level is the least of the damage, degradation, or upset levels considering all electronic components potentially affected by conducted or radiated transients.

3.67 Transient

An overvoltage or overcurrent pulse on a power, signal, control, or data line.

3.68 Transient Suppressor

Components, devices or circuits designed for the purpose of attenuating, absorbing and suppressing conducted transient and surge energy to protect facility equipment.

3.69 Turn-on Voltage

The voltage required across transient suppressor terminals to cause the suppressor to conduct current.

3.70 Zone of Protection

The zone of protection is that space adjacent to a lightning protection system that has a reduced probability of receiving a direct lightning strike.

4 GENERAL REQUIREMENTS

4.1 Requirements Common to Both Facilities and Equipment

This section provides requirements that are established to ensure the proper operation of FAA facilities and equipment. The use of the term “facilities” in this document can differ from the manner in which it is frequently used in other FAA documents. In this document, physical proximity of equipment(s) defines a single facility, while physical separation would define separate facilities. For example, the cab and electronic/electrical equipment located on the junction and subjunction levels of an Airport Traffic Control Tower (ATCT) are a single facility.

An ATCT with a base building containing electronic equipment is an example of two facilities located at the same site. Other examples of two or more facilities include the ARSR-4 (the tower and base building are separate facilities) and Air Route Traffic Control Centers (ARTCC) with multiple buildings that must be treated as separate facilities. An example of a single facility (for purposes of this document) is a Remote Controlled Air to Ground Site (RCAG) collocated in a VHF Omni-directional Range (VOR) building. Contact the Office of Primary Responsibility (OPR) of this document for specific guidance on new facilities/systems.

4.1.1 Bonding Requirements

4.1.1.1 Resistance of Bonds

Unless otherwise specified in this standard, all bonds shall have a maximum DC resistance of 1 milliohm when measured between the bonded components with a 4-terminal milliohmmeter.

4.1.1.2 Methods of Bonding

Bonding for electrical purposes shall be accomplished by a method that provides the required degree of mechanical strength, achieves the value of low and high frequency impedance required for proper functioning of the equipment. Soft soldered or brazed connections shall not be used for any part of the power grounding system, EES or the lightning protection system (air terminals, roof conductors, down conductors, fasteners, and conduit). Soft solder shall only be used to improve conductivity at joints already secured with mechanical fasteners. Soft solder shall not be used to provide mechanical restraint.

4.1.1.2.1 Exothermic Welds

Exothermic welds shall be allowed for any type of bond connection specified herein.

Exothermic welds shall be used for all buried or subject to submersion connections. Where exothermic welds are not be possible between certain materials, shapes, or in hazardous locations, i.e., near fuel tanks, where nearby objects are subject to damage, etc., connections using UL listed connectors shall be permitted. Exothermic welding shall be used for the permanent bonding of copper conductors to steel. Where the combustion products of a standard exothermic weld present problems, a smokeless exothermic process is commercially available and shall be used. All residual fluxes shall be removed or neutralized to prevent corrosion.

4.1.1.2.2 Welded Assemblies

Individual components of a welded assembly shall not require additional bonds between components if the DC resistance between individual components is less than 1 milliohm.

4.1.1.2.3 Dissimilar Metals

Mechanical bonds shall comply with Table I unless specifically approved by the OPR.

The legend shown below is for Table I and represents the four basic categories of possible metal interfaces.

no Not suitable. This interface is highly likely to result in significant corrosion.

• Suitable for indoor environments where temperature and humidity are controlled

(non-condensing environment).

•• Suitable for all indoor environment.

••• Suitable for all environments.

Table I. Mechanical Bonds Between Dissimilar Metals

METAL

C op pe r, so lid o r p la te

B ra ss a nd b ro nz e

S ta in le ss S te el

Ti n-pl at e;

ti n-le ad s ol de r

A lu m in um , w ro ug ht a llo ys o f t he

S er ie s

Iro n, w ro ug ht

, g ra y or m al le ab le , p la in ca rb on a nd lo w a llo y st ee ls

A lu m in um , w ro ug ht a llo ys o th er th an

S er ie s al um in um

, c as t a llo ys o f t he s ili co n ty pe

A lu m in um , c as t a llo ys o th er th an s ili co n ty pe , p la te d an d ch ro m at e

G al va ni ze d st ee l

Zi nc

, w ro ug ht

; z in c-ba se d ie -c as tin g al lo ys zi nc p la te d

Copper, solid or plate ••• ••• •• • • • no no no no

Brass and bronze ••• ••• •• •• • • • no no no

Stainless Steel •• •• ••• ••• ••• •• • • no no

Tin-plate; tin-lead solder • •• ••• ••• ••• •• •• • no no

Aluminum, wrought alloys of the 2000 Series • • ••• ••• ••• ••• ••• •• • •

Iron, wrought, gray or malleable, plain carbon and low alloy steels • • •• •• ••• ••• ••• ••• • •

Aluminum, wrought alloys other than 2000 Series aluminum, cast alloys of the silicon type no • • •• ••• ••• ••• ••• • •

Aluminum, cast alloys other than silicon type, plated and chromate no no • • •• ••• ••• ••• •• •

Galvanized steel no no no no • • • •• ••• •••

Zinc, wrought; zinc-based die-casting alloys; zinc plated no no no no • • • • ••• •••

4.1.1.2.4 Mechanical Connections

4.1.1.2.4.1 Coupling of Dissimilar Metals

Compression bonding with bolts and clamps should be used between metals having acceptable couples depending on the location as shown in Table I. When the base metals form couples that are not allowed, the metals shall be coated, plated, or otherwise protected with a conductive finish. MlL-STD-889 provides specific information in this area.

4.1.1.2.4.2 Bolted Connections for Electrical Bonding

Bolts shall be used primarily as mechanical fasteners for holding the component members of the bond in place. Bolts shall be tightened sufficiently to maintain the contact pressures required for effective bonding but shall not be over-tightened to the extent that deformation of bond members occurs. Disc springs (Belleville spring washers) shall be installed on all bolted connections ¼ inches diameter and greater to prevent loosening. Bolted joints other than those intentionally used to attach bonding straps or conductors, shall not be used in lieu of dedicated bonding jumpers.

a) All bolted connections ¼ inches diameter and greater shall conform to the torque requirements in Table II.

b) All bolted connections in corrosive, damp, or wet locations, ¼ inches diameter and greater shall utilize stainless steel bolts, nuts, and load distribution washers to meet the strength requirements of same size SAE Standard J429 Grade 5. All other locations shall use corrosion inhibited SAE Standard J429 Grade 5 nuts and bolts. Load distribution washers shall comply with ANSI B18.22.1 for stainless steel washers, Wide Series, Type B.

c) Bolted connections ¼ inches diameter and greater shall be assembled in the order shown in Figure I. Additional load distribution washers, if used, shall be positioned directly underneath the bolt head. Disc springs shall be between the nut and the load distribution washer. Washers shall not be placed between bonded members. Load distribution washers be wide Series, Type B.

Table II. Torque Requirements for Bolted Bonds

Bolt Size Torque (ft-lbs)

Bolt Load (lbs)

Washers Required

Solon Part Number*

1/4 in. 10 2500 3 4-EH-70-301 5/16 in. 21 4000 3 5-EH-80-301 3/8 in. 34 5500 3 6-EH-89-301 7/16 in. 55 7500 6 7-L-70-301 1/2 in. 83 10,000 2 8-18-125-301 9/16 in. 117 12,500 N/A N/A 5/8 in. 167 16,000 3 10-EH-150-177 3/4 in. 288 23,000 3 12-EH-168-177 7/8 in. 452 31,000 3 14-EH-168-177 1 in. 567 40,000 3 15-H-187-177

*Other manufacturers of disc spring washers are equally suitable

Bond Strap

Belleville Washer

Metal Member

Note:

Belleville Washer

Load Distribution Washer

Remove all paint on the whole bonding area of the metal member.

Stack Belleville washers to obtain required number.

Figure I. Order of Assembly for Bolted Connections

4.1.1.2.4.3 Sheet Metal Screws

Sheet metal screws shall not be used to provide an electrical bond.

4.1.1.2.4.4 Hydraulically Crimped Terminations

Where crimped connectors are used for conductors 6 AWG or larger, the connectors shall be accomplished hydraulically using a minimum force of 12 tons concentrically applied.

4.1.1.2.4.5 Soldering

The use of silver solder to improve mechanical bonds by excluding contaminants from the mating surfaces shall be allowed. Mechanical bonds shall be mechanically secured prior to applying solder to prevent cold solder joints. Soldered mechanical connections shall not be used for any part of the power grounding system or the lightning protection system. See FAA Order 6950.20, Chapter 5, paragraph 99 for additional information.

4.1.1.2.4.6 Riveting

Rivets shall be employed solely as mechanical fasteners to hold multiple smooth, clean metal surfaces together or to provide a mechanical load bearing capability to a soldered bond.

4.1.1.3 Bonding Straps and Jumpers

Bonding straps, including jumpers, shall conform to the following:

(a) Bonding jumpers shall be insulated except those used under a raised floor which shall be bare. Bonding jumpers for structural steel, rebar, connected to the EES, the lightning protection system, and any plenum or environmental airspace shall be bare also. Short bonding straps may be bare. ( This requirement is to maintain compliance with the requirements of the NEC)

(b) Bonding straps shall be attached to the basic component rather than through any adjacent parts.

(c) Bonding straps shall be installed so that the electrical bond is not affected by motion or vibration.

(d) Braided bonding straps shall not be used for bonding transmitters or other sources of radio frequency (RF) fields.

(e) Bonding straps shall be installed whenever possible in areas accessible for maintenance and inspection.

(f) Bonding straps shall be installed so they will not restrict movement of the components being bonded or other components nearby which must be able to move as part of normal functional operation.

(g) Two or more bonding straps shall not be connected in series to provide a single bonding path.

(h) The method of installation and point of attachment of bonding straps shall not weaken the components to which they are attached.

(i) Bonding straps shall not be compression-fastened through non-metallic material.

(j) Bonding straps shall be designed not to have resonant impedances at equipment operating frequencies. Two short, low-impedance grounding straps between the signal reference structure and two corners of the equipment should be used. These straps shall be connected as far apart as possible on the equipment (ideally on opposite corners) in order to reduce mutual inductance and they shall have few bends or sags. Two straps with a 20% to 30% difference in length should be used so that if one strap experiences resonance, limiting current flow, the other strap will not.

(k) The length of the equipment bonding conductor connections shall be as short as possible and ideally be limited to 1/20th of a wavelength of the signal frequency, e.g., about six inches at 100 MHz.

(l) Broad flat conductors, with a large surface area (at least one inch wide) shall be used for bonding straps since they have a lower inductance than round conductors. All bonding straps shall be fabricated with integral terminations that approximate the width of the strap, permitting proper terminations. Lower impedance can be achieved by multiple bonds.

4.1.1.4 Fasteners

Fastener materials for bonding aluminum and copper jumpers to structures shall conform to the materials listed in Table I.

4.1.1.5 Temporary Bonds

Alligator clips and other spring loaded clamps shall be employed only as temporary bonds while performing repair work on equipment or facility wiring.

4.1.1.6 Inaccessible Locations

All bonds in permanently concealed or inaccessible locations shall be exothermically welded.

4.1.1.7 Surface Preparation

All surfaces to be bonded shall be thoroughly cleaned to remove all dirt, grease, oxides, nonconductive films, or other foreign material. Paints and other coatings shall be removed to expose the base metal.

4.1.1.7.1 Area to Be Cleaned

Clean all surfaces at least 1/4 inches (6.4 mm) beyond all sides of the larger bonded area on all mating surfaces.

4.1.1.7.2 Final Cleaning

Clean surfaces with a solvent suitable for electrical work immediately prior to assembly.

4.1.1.7.2.1 Clad Metals

Clean clad metal to a bright, shiny, smooth surface without penetrating the cladding. Wipe the cleaned area with solvent and allow to air dry before completing the bond.

4.1.1.7.2.2 Aluminum Alloys

A conductive finish shall be applied to aluminum mating surfaces after cleaning to a bright finish.

4.1.1.7.3 Completion of the Bond

Mating surfaces shall be joined within 2 hours after cleaning if an intentional protective coating has been removed from the metal surface. If delays beyond two hours are necessary in corrosive environments, the cleaned surfaces must be protected with an appropriate coating that must be removed before completion of the bond.

4.1.1.7.4 Refinishing of Bond

Where practicable restore areas around bonds so as to match the original finish.

4.1.1.7.5 Surface Plating or Treatments

Surface treatments that include plating provided for added abrasion resistance or corrosion protection shall offer high conductivity. Unless suitably protected from the atmosphere, silver and other easily tarnished metals shall not be used to plate bond surfaces, except where an increase in surface contact resistance cannot be tolerated.

4.1.1.8 Bond Protection

All bonds shall be protected against weather, corrosive atmospheres, vibration, and mechanical damage. Under dry conditions, apply a compatible corrosion preventive or sealant, within 24 hours of assembly of the bond materials. Under conditions exceeding 60% humidity, seal the bond with a compatible corrosion preventive or sealant within 1 hour of joining.

4.1.1.8.1 Paint

If a paint finish is required on the final assembly, the bond shall be sealed with the recommended finish. Care shall be taken to assure that all means by which moisture or other contaminants enter the bond are sealed. A waterproof type of paint or primer shall be used if the recommended finish is not waterproof.

4.1.1.8.2 Compression Bonds in Protected Areas

Sealing is not required for compression bonds between copper conductors or between compatible aluminum alloys located in readily accessible areas that are not exposed to moisture, corrosive fumes, or excessive dust.

4.1.1.8.3 Corrosion Protection

All exterior and interior bonds exposed to moisture or high humidity shall be protected against corrosion. All interior bonds made between dissimilar metals shall be protected against corrosion in accordance with paragraph 4.1.1.2.3 and paragraph 4.1.1.2.4.1. All exothermic welds shall be cleaned of all residual slag. Protection shall be provided by a moisture proof paint conforming to the requirements of FAA-STD-012 or shall be sealed with a silicone or petroleum-based sealant to prevent moisture from reaching the bond area. Bonds protected by conductive finishes (alodine, iridite, et. al.) shall not require painting to meet the requirements of this standard.

4.1.1.9 Bonding across Shock Mounts

Bonding straps installed across shock mounts or other suspension or support devices shall not impede the performance of the mounting device. They shall be capable of withstanding the anticipated motion and vibration requirements without suffering metal fatigue or other failures.

4.1.1.10 Enclosure Bonding

Directly bond subassemblies and equipment at the areas of physical contact with the mounting surface.

4.1.1.11 Subassemblies

Utilize the maximum possible contact area when bonding subassemblies to the chassis. All feed throughs, filters, and connectors shall be bonded around the periphery to the subassembly enclosure to maintain shield effectiveness. Covers shall exhibit intimate contact around their periphery, and contact shall be achieved and maintained through the use of closely spaced screws or bolts, or the use of resilient conductive gaskets, or both. Note: COTS equipment should be treated as a sealed unit for the purposes of this requirement.

4.1.1.12 Equipment

The chassis or case of equipment shall be directly bonded to the rack, frame, or cabinet in which it is mounted. Clean all flange surfaces and the contact surface on the supporting element of all paint or other insulating substances in accordance with the requirements of paragraph 4.1.1.7.

Fasteners shall maintain sufficient pressure to assure adequate surface contact to meet the bond resistance requirements in paragraph 4.1.1.1. Captive nuts and sheet metal screws shall not be used for fasteners. If equipment must remain operational when partially or completely withdrawn from its mounted position, the bond shall be maintained by a moving area of contact or by the use of a flexible bonding strap. Mechanical designs shall employ direct bonding, without straps, whenever feasible.

4.1.1.13 Connector Mounting

All metal or metallized connectors shall be mounted so that electrical contact is maintained between the connector body and the panel to which it is mounted. Bonding shall be accomplished completely around the periphery of the flange of the connector. Both the flange surface and the mating area on the panel shall be cleaned in accordance with paragraph 4.1.1.7.

All nonconductive material shall be removed from the panel as illustrated in Figure II. After mounting of the connector, the exposed area of the panel shall be repainted or otherwise protected from corrosion in accordance with paragraph 4.1.1.8.

4.1.1.14 Shield Terminations

Cable shields shall be terminated in the manner specified by paragraphs 4.1.2.3.2 and 4.1.2.3.3.

Shields of axial cables shall be fastened tightly to the cable connector shell with a compression fitting or soldered connection. The cable shall be able to withstand the anticipated use without becoming noisy or suffering a degradation in shielding efficiency. Axial connectors shall be of a material that is corrosion resistant in keeping with requirements of FAA-G-2100. Low frequency shields shall be soldered in place or, if solderless terminals are used, the compressed fitting shall afford maximum contact between the shield and the terminal sleeve. Shield pigtails shall extend less than 1 inch from the point of breakaway from the center conductors of the cable.

Figure II. Bonding of Connectors to Mounting Surface

4.1.1.15 RF Gaskets

Conductive gaskets shall be made of corrosion resistant material, shall offer sufficient conductivity to meet the resistance requirements of paragraph 4.1.1.1, and shall possess adequate strength, resiliency, and hardness to maintain the shielding effectiveness of the bond. The surfaces of contact with the gasket shall be smooth and free of insulating films, corrosion, moisture, and paint. The gasket shall be firmly affixed to one of the bond surfaces by screws, conductive cement, or other means that do not interfere with the effectiveness of the gasket; or a milled slot shall be provided that prevents lateral movement or dislodging of the gasket when the bond is disassembled. Gaskets shall be a minimum of 1/8 inch wide. The gasket as well as the contact surfaces shall be protected from corrosion.

4.1.2 Shielding Requirements

4.1.2.1 Design

The facility design and construction shall incorporate both protective shields to attenuate radiated signals, and separation of equipment and conductors to minimize the coupling of interference.

The equipment design shall incorporate component compartments and overall shields as necessary to meet the electromagnetic susceptibility and emission requirements of MIL-STD-461 as required by NAS-SS-1000 and FAA-G-2100. In addition, the design shall provide the shields necessary to protect personnel.

4.1.2.2 Facility Shielding

Shielding of facility buildings, shelters or equipment spaces shall be provided when other facility or environmental sources of radiation are of sufficient magnitude to degrade the operation and performance of electronic equipment or system. Where rebar or a rudimentary Faraday cage exists, it shall be connected to the EES with a minimum 2 AWG copper conductor that is applied via an exothermic weld or a hydraulically crimped termination.

4.1.2.3 Conductor and Cable Shielding

Conductor and cable shielding shall comply with the following sub-paragraphs:

4.1.2.3.1 Signal Lines and Cables

Cables consisting of multiple twisted pairs shall have individual shields for each twisted pair..

The shields shall be isolated from each other. Cables with an overall shield shall have the shield insulated and isolated from the individual shields..

4.1.2.3.2 Termination of Individual Shields

Shields of pairs of conductors, line shields, and the shield of cables containing unshielded conductors shall be terminated in accordance with the following:

(a) Shields shall be terminated to ensure correct equipment operation.

(b) Shield terminations shall employ minimum length pigtails between the shield and the connection to the bonding halo or ferrule ring and between the halo or ferrule ring and the shield pin on the connector. The unshielded length of a signal line shall not exceed 1 inch (25 mm) with not more than 1/2 inch (13 mm) of exposed length as the desired goal.

(c) Shields, individually and collectively, shall be isolated from overall shields of cable bundles and from electronic equipment cases, racks, cabinets, junction boxes, conduit, cable trays, and elements of the electronic multipoint ground system. Except for one interconnection, individual shields shall be isolated from each other. This isolation shall be maintained in junction boxes, patch panels and distribution boxes throughout the cable run. When a signal line is interrupted such as in a junction box, the shield shall be carried through. The length of unshielded conductors shall not exceed 1 inch (25 mm). To meet this requirement, the length of shield pigtail longer than 1 inch shall be allowed but shall be the minimum required.

(d) Circuits and chassis shall be designed to minimize the distance from the connector or terminal strip to the point of attachment of the shield grounding conductor to the electronic signal reference. The size of the wire used to extend the shield to the circuit reference shall be as large as practical but shall not be less than 16 AWG or the maximum wire size that will fit the connector pin.