AFI32-1065_AFSPCSUP1_I_2012.pdf

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COMPLIANCE WITH THIS PUBLICATION IS MANDATORY

BY ORDER OF THE

SECRETARY OF THE AIR FORCE

AIR FORCE INSTRUCTION 32-1065

1 OCTOBER 1998

AIR FORCE SPACE COMMAND

Supplement 1

3 FEBRUARY 2003

Civil Engineering

GROUNDING SYSTEMS

OPR: HQ AFCESA/CESE

(Col H. Dean Bartel)

Certified by: HQ AFCESA/CC (Mr Larry W. Strother)

Supersedes AFI 32-1065, 29 April 1994.

AFI32-1065_AFSPCSUP1, 1 Feb 99

Pages: 39 Distribution: F

This instruction implements AFPD 32-10, Installations and Facilities. It assigns maintenance responsi-bilities and requirements for electrical grounding systems on Air Force installations. This includes sys-tems for equipment grounding, lightning protection, and static protection. This instruction also implements the maintenance requirements of DoD 6055.9-STD, Ammunition Explosives Safety Stan-dards, Chapter 7, Lightning Protection, August 1997, for potentially hazardous explosives facilities.

Send all recommendations for changes or improvements to this instruction on AF Form 847, Recommen-dation for Change of Publication, through the major commands (MAJCOM) and HQ AFCESA/CESE, 139 Barnes Drive, Suite 1, Tyndall AFB FL 32403-5319 to HQ USAF/ILEO, 1260 Air Force Pentagon, Washington DC 20330-1260. See Attachment 1 Glossary of references and supporting information used in this instruction.

(AFSPC) The OPR for this supplement is AFSPC CEF/CEO (Mr. Richard Coder). This sup ple-ment implements and extends the guidance of Air Force Instruction (AFI) 32-1065, Grounding Sys-tems. The AFI is published word-for-word without editorial review. Air Force Space Command (AFSPC) supplemental material is indicated in bold face. This supplement describes AFSPC’s pro-cedures for use in conjunction with the basic AFI. I t applies to AFSPC organizations that design, develop, modify, evaluate, or maintain grounding systems. Specifically, this guidance pertains to all storage and maintenance facilities to include igloos, underground and above ground structures. It applies to Air For ce Reserve Units and Air National Guard Units who operate as part of AFSPC.

Send a copy of NAF or unit supplements and suggested changes to this supplement to AFSPC CEF, 1520 E. Willamette Ave., Colorado Springs, CO 80909-4554 f or final approval before publication.

Upon receipt of this integrated supplement discard the Air Force basic publication.

Certified Current 11 January 2012 http://

2 AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003

SUMMARY OF REVISIONS

This document is substantially revised and must be completely reviewed.

This revision incorporates the latest changes to DoD 6055.9-STD.

(AFSPC) Revisions are as follows. Qualification and certification requirements for LPS personnel were redefined. Contractor support requirements were clarified. References to Air Force and industry standards were modernized. Provision to ensure personal and system safety was given priority over aesthetic appeal was added. New construction standards were clarified. A bar ( | ) indicates a revision.

Section A Maintenance Policy 4

1. Responsibilities

Table 1. Scheduled Maintenance for Grounding Systems

2. Codes and Specifications

3. Required Maintenance

4. Recordkeeping and Review

5. Forms

6. Personnel Qualifications

7. Developing Procedures

Section B Grounding Resistance and Continuity Tests and Visual Inspections 10

8. Testing Requirements

9. Visual Inspections of Lightning Protection Systems

10. Visual Inspection of Facility Grounds

Section C Grounding and Lightning Protection Requirements 11

11. Introduction

12. Testing and Inspecting Static and Lightning Protection Systems and

Figure 1. Example Sketch of Test Points (Typical)

13. Static Protection

14. Lightning Protection Systems

15. Surge Protection

Attachment 1— GLOSSARY OF REFERENCES AND SUPPORTING INFORMATION 16

Attachment 2— BASIC REQUIREMENTS FOR GROUNDING SYSTEMS 20

A2.1. Types of Grounds

AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003 3

A2.2. NEC Grounding Requirements

A2.3. Grounding Electrodes:

A2.4. Grounding and Corrosion

Attachment 3— BASIC BONDING REQUIREMENTS

A3.1. Basic Requirements

A3.2. Condition 1

A3.3. Condition 2

Figure A3.1. Typical Bonding Conditions in Structures 12.2 Meters (40 Feet) or Less

Figure A3.2. Typical Bonding Conditions in Structures Greater Than 12.2 Meters (40 Feet)

A3.4. Condition 3

Figure A3.3. Typical Bonding Conditions for Ungrounded Metal Bodies

A3.5. Typical Air Force Situation

A3.6. Explosives Facility Bonding

Figure A3.4. Bonding for Typical Air Force Structure

Figure A3.5. Approximate Bonding Distances

A3.7. Protective Aircraft Shelters (PASs)

Attachment 4— LIGHTNING PROTECTION SYSTEMS 32

A4.1. Minimum Requirements

A4.2. Mast and Overhead Wire Systems:

Figure A4.1. Air Terminals on Masts (Typical)

Attachment 5— MAINTENANCE GUIDELINES FOR EXPLOSIVES FACILITIES 34

A5.1. Has each facility been inspected to determine the type of protection system installed? 34

A5.2. Are personnel from the testing agency familiar with lightning protection systems? 34

A5.3. Are all test agency personnel who could or do perform the tests

A5.4. Are static grounding systems installed as separate subsystems?

A5.5. Are both the user and testing agencies aware of all facilities

A5.6. Are tests/inspections accomplished at the required frequency?

A5.7. Are tests conducted with the proper test instruments?

A5.8. Are personnel conducting tests familiar with the location of test points

A5.9. Are visual inspections being performed as required?

A5.10.Are repair actions taken to render the facility safe?

4 AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003

A5.11.After repair actions have been completed, are electrical tests accomplished

Attachment 6— TESTING REQUIREMENTS 35

A6.1. Grounding System Resistance Test

Figure A6.1. Auxiliary Probe Locations for Fall-of-Potential Ground Resistance Test

A6.2. Resistance Test for Above-Ground Petroleum (POL) Tanks

Figure A6.2. Measuring Resistance to Earth of Large POL Tank

A6.3. Resistance Test for Large Objects

Figure A6.3. Alternate Method of Measuring Resistance to Earth of Large Object

A6.4. Continuity Test/Check for Separately Mounted Lightning Protection Sys

A6.5. Continuity Test/Check for Integrally Mounted Lightning Protection Sys

A6.6. Testing for Static Bus Bars

Figure A6.4. Mast and Overhead Shield Wire Protection System

A6.7. Conductive Floor Tests

Figure A6.5. Testing Static Bus Bars in Typical Explosives Area

Section A—Maintenance Policy

1. Responsibilities.

1.1. The Base Civil Engineers (BCE):

1.1.1. Maintain lightning and grounding systems specifically identified in Table 1 . according to the procedures in this instruction.

1.1.2. Make sure that user organizations identified in Table 1 . are aware of their maintenance responsibilities.

1.1.3. Train users to perform their responsibilities to inspect and maintain lightning and ground-ing systems as identified in Table 1. when requested.

AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003 5

Table 1. Scheduled Maintenance for Grounding Systems.

FACILITY ACTION REQUIRED FREQUENCY

RESPONSI-

BILITY REFERENCE

1. Exterior Elec tri-cal Distribution

Visual inspec tion of equipment fencing, pole grounds, and neutrals

2 years Base Civil Engineer

AFJMAN

32-1082

2. Electric al Sub-station

Resistance check (5 ohms max)

5 years Base Civil Engineer

This AFI

3. Ext erior Light -ning Arresters

Visual Annually Base Civi l Engineer

AFJMAN

32-1082

4. General a. Visual inspection and resistance check of facility grounds (25 ohm max for single electrode system)

5 years Base Civil Engineer

This AFI, NFPA 70

b. Visual inspection of lightning protection system

1-3 years Base Civil Engineer

This AFI

5. POL Facilities a. Resistance check on static grounds (10,000 ohms max)

When i nstalled or physically damaged

Base Civi l Engineer

AFM 85-16

b. Visual inspection and check t ightness on ground conductors

Quarterly Base C ivil Engineer

AFM 85-16

6. Aircraft Parking Apron Grounds and Hanga r Floor Static Grounds

Resistance che ck on static grounds (10,000 ohms max)

When i nstalled or physically damaged

Base Civi l Engineer

AFM 8 8-9,

Chapter 3

7. LOX Storage Resistance check on static ground (10,000 ohms max)

When i nstalled or physically damaged

Base Civi l Engineer

This AFI

8. Ra il Ca r Off-loading Spur

Visual inspection of rail bonding

Quarterly Base C ivil Engineer

AFM 85-16

9. C ommuni-ca-tion Fa cilities (Including TEM -

PEST)

Resistance check (10 ohms max is design objective)

Quarterly f or first yea r afte r installation;

then eve ry 21 months

Base Civi l Engineer

AFI 32-1063;

MIL-HD-

BK-419A

10. C ommuni-ca-tion Facilities

Checks i nvolving in-house elec tronic equipment ground

Determined by user

User AFI 32-1063

6 AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003

11. H azardous* Explosive Area (Weapons)

a. Visua l inspec tion of static wires and bonds

Before using equipment eac h day

User AFMAN 91-201

b. Cont inuity chec k from equipment to stat-ic ground bar (1 ohm max)

3 months or ac -cording to spe -cific item T.O.

User AFMAN 91-201;

this AFI

c. Cond uctive floor grounding che ck (spe -cific ohm ic re -quire-ments c ontained in AFMAN 91-201)

6 months Base Civil Engineer

AFMAN

91-201;

this AFI

d. S ee non- hazardous explosives r equire-ments 12c, 12d, 12e, and 12f.

Base Civi l Engineer

AFMAN

91-201;

this AFI

12. Non-Haz ard-ous* Explosi ve Area (Weapons)

a. Visua l inspec tion of static wire bonds

Quarterly User AFMAN 91-201;

this AFI

b. Conti nuity c heck on static bond fr om equip-ment to static ground

24 months User AFMAN 91-201

c. Visua l inspec tion of lightning protection

12 months Base Civil Engineer

AFMAN

91-201;

this AFI

d. R esistance c heck on lightning p rotection earth ground system (25 ohms m ax except Ground Loop System)

24 months Base Civil Engineer

AFMAN

91-201;

this AFI

e. Continui ty c heck on air ter minals, bonds, and conductors (1 ohm)

24 months Base Civil Engineer

AFMAN

91-201; this

AFI

f. S tatic bus bar conti-nuity to ground (1 ohm)

24 months Base Civil Engineer

AFMAN

91-201; this

AFI

13. Protective Air-craft Shelter

(PAS)***

a. Ground system resis-tance check

24 months Base Civil Engineer

This AFI

FACILITY ACTION REQUIRED FREQUENCY

RESPONSI-

BILITY REFERENCE

AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003 7

* As defined in NEC Article 500

** Base Civil Engineers will perform if separate medical facility maintenance branch does not exist.

with Weapon Stor-age and Se curity System (W S3) Vault

b. Visual inspec tion of system

6 months Base Civil Engineer

This AFI

c. Conti nuity betwee n arch and ground

24 months Base Civil Engineer

This AFI

d. Test door hinges (1 ohm max)

24 months Base Civil Engineer

This AFI

e. Conti nuity betwee n vault lip (flange) a nd ground (conduit)

24 months Base Civil Engineer

This AFI

f. Conti nuity of in-stalled ( permanent) bonds betwee n m etal masses and steel arch

24 months Base Civil Engineer

This AFI

14. Fuels Lab a. Visual and continuity check of ground wires

Monthly User AFOSH S TD 91-38

b. Visual inspec tion of facility grounds

Monthly User AFOSH S TD 91-38

15. Medica l** Fa-cilities

a. Resistance check (25 ohms max)

Every 5 years Base Civil Engineer

NFPA 99

b. E ffectiveness of grounding system by voltage a nd im pedance measurements

Before ac -cept-ance of new or afte r modifica-tion

Base Civi l Engineer

AFI 41-203;

NFPA 99

c. Verification of conti-nuity of rec eptacle grounding circuits

Annual (semi-annual for critical c are a r-eas)

Base Civi l Engineer

AFI 41-203

16. Airf ield Light-ing Grounds

Resistance chec k (25 ohms max)

2 years Base Civil Engineer

This AFI

17. EMP Hardened Facilities

(These fa cilities m ay have spec ial require-ments)

Base Civi l Engineer;

user

DNA-A-86-60,

Vol 1-3; this

AFI

18. PMEL Continuity and re -sist-ance test of fa cility ground (25 ohms max)

2 years Base Civil Engineer

This AFI

FACILITY ACTION REQUIRED FREQUENCY

RESPONSI-

BILITY REFERENCE

8 AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003

*** Also known as Hardened Aircraft Shelter (HAS)

1.1.4. Review the lightning protection system on each facility at least annually or a fter repair actions have been completed.

1.1.5. (Added- AFSPC) Ensure that all personnel testing, inspecting, repairing, modifying, or maintaining lightning and grounding systems are qualified or that their work is inspected by a person who is qualified.

1.1.6. (Added-AFSPC) Ensure there is a minimum of one qualified lightning and grounding system certifier at all times.

1.1.6.1. (Added-AFSPC) Maintain a current designation letter appointing the lightning and grounding system certifier/s.

1.1.6.2. (Added-AFSPC) Send a copy of the designation letter referenced in 1.1.6.1. to

AFSPC CEF/CEO.

1.2. Users. Users will maintain lightning and electrical grounding systems as identified in Table 1.

1.2.1. (Added-AFSPC) Contract Support. When contract support is used to maintain, mod-ify, or install lightning and grounding systems the contract shall require the contractor per-sonnel to have standard commercial certifications (such as Underwriter’s Laboratories) and to maintain the systems in accordance with industry standards, NFPA 780-Standard for Installation of Lightning Protection Systems, AFI 32-1065-Gr ounding Systems, and AFI32-1065_AFSPCSUP1, Grounding Systems. The contractor is not required to receive or maintain qualifications through the Air Fo rce Qualification program. Contractors who attend AFSPC approved lightning protection systems course and receive the required certif-icate of completion still are required to maintain all standard commercial certificates. The contractor shall provide a copy of all test records to the Unit Chief of Operations (CEO) for review and trend analysis. Records will be maintained within CEO a s required in AFI 32-1065. A copy of a ll test results shall be pr ovided to muni tions personnel per AFI 21-204_AFSPCSUP1, Nuclear Weapons Procedures. Facilities maintained through contract support will be subject to surveillance and compliance inspections at the discretion of the supporting installation Civil Engineer Squadron and Safety Organization. Air Force and HQ AFSPC personnel may also conduct and direct surveillance and compliance inspections.

1.2.2. (Added-AFSPC) Lease Agreements and Contracts. Facilities on Air Force installa-tions leased to outside agencies or contractors are subject to the requirements of paragraph 1.2.1.

2. Codes and Specifications. Follow applicable codes and specifications in Attachment 1 unless mod-ified in this instruction, or deviations are justified due to local conditions.

2.1. (Added-AFSPC) Personnel shall comply with all portions of NFPA 780, Standard for Instal-lation of Lightning Protection Systems, to include the Appendices. If there is a conflict with pub-lications listed in attachment 1 of AFI32-1065, the more stringent criteria will apply.

3. Required Maintenance. Perform required maintenance at the frequencies specified in Table 1. When possible, plan for and schedule maintenance when facility users will be least affected.

AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003 9

4. Recordkeeping and Review.

4.1. Inspectors and testers must compile and maintain records of t heir inspections and tests to include:

4.1.1. A sketch of the grounding and lightning protection system showing test points, and where services enter the f acility. Sketch should also show the location of the probes during the ground resistance test. (Separate sketches are suggested for static, earth ground, and lightning protection systems on large complex facilities.)

4.1.2. Date action was performed.

4.1.3. Inspector's or tester’s name.

4.1.4. General condition of air terminals, conductors, and other components.

4.1.5. General condition of corrosion protection measures.

4.1.6. Security of attachment for conductors and components.

4.1.7. Resistance measurements of the various parts of the ground terminal system.

4.1.8. Variations from the requirements of this instruction.

4.1.9. Discrepancies noted and corrective actions taken.

4.1.10. Date of repairs.

4.2. Review records for deficiencies; also analyze the data for undesirable trends. If test values differ substantially from previous or original tests obtained under the same test procedure and conditions, determine the reason and make necessary repairs.

4.3. Keep test and inspection records for a minimum of six inspection cycles.

5. Forms. Suggest the use of Air Force general purpose forms (3100 series) to record tests. Use the for-mat listed in MIL-HDBK-419A, Grounding, Bonding, and Shielding for Electronic Equipments and Facilities for communications facilities. Provide copies of completed forms to the faci lity user. For munitions facilities maintained by host nation civil engineers, the using agency must receive a copy of the completed forms.

6. Personnel Qualifications. Workers maintaining, repairing, modifying, and testing grounding systems must be thoroughly familiar with test equipment operation; lightning protection, grounding, and bonding theory and practices; referenced codes and standards; and specific requirements and procedures in this instruction. Attachments 2 through 5 provide information suitable for use in training and familiarization.

6.1. (Added-AFSPC) Qualification Requirements: Pass the Air Force Space Command spon-sored lightning protection course and receive the required certificate of completion.

6.1.2. (Added-AFSPC) Demonstrate the knowledge, skills, and abilities to effectively admin-ister the requirements of referenced codes and standards to their lightning and grounding system certifier during daily work.

6.1.3. (Added-AFSPC) Personnel who have not worked in lightning and grounding for at least two full consecutive years must repeat the requirements of 6.1.1. and 6.1.2. to be consid-ered qualified.

10 AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003

6.1.4. (Added-AFSPC) Contractors maintaining lightning and grounding systems do not need to meet the requirements of 6.1.1. through 6.1.3. However, the contract and contractor must meet the provisions of section 1.2.1.

6.2. (Added-AFSPC) Ligh tning and Grounding System Certifier Qualification Requirements:

Pass the Air Force Space Command approved lightning protection course and receive the required certificate of completion.

6.2.1. (Added-AFSPC) Pass t he Air Force Space Command approved lightning protection course and receive the required certificates of completion.

6.2.1.1. (Added-AFSPC) Repeat the course as a refresher at intervals no greater than six years.

6.2.2. (Added-AFSPC) Experience designing, testing, inspecting, repairing, modifying, and maintaining lightning and grounding systems.

7. Developing Procedures. The organization performing inspections and tests must develop procedures based on the requirements in this instruction.

7.1. (Added-AFSPC) Procedures shall require AFSPCCL32-13, Explosives Safety, Hoists, Emer-gency Power and Lightning Protection for Weapons Areas, to be run against each structure with Lightning protection. Each lightning protection system must be considered independently to ensure guidance is properly implemented.

Section B—Grounding Resistance and Continuity Tests and Visual Inspections

8. Testing Requirements. See Attachment 6 for resistance and continuity test requirements for typical systems. Instruments must be able to measure 10 ohms +10 percent for ground resistance tests, and 1 ohm +10 percent for continuity testing. Only instruments designed specifically for earth-ground systems are acceptable for ground resistance testing. Follow the ma nufacturer's instruction manual except as modi-fied herein when using the instruments. Earth ground resistance should be less than 25 ohms unless spec-ified different in this document. Periodic tests should be made at approximately the same time each year to minimize confusion resulting from seasonal changes (see Attachment 2). If the resistance measured during continuity tests is greater than 1 ohm, check for deficiencies and repair, then retest. When per-forming a continuity test over very long lengths of conductors (more than 20m with no parallel paths), readings above one ohm but less than 3 ohms may occur. This is acceptable. The MAJCOM electrical engineer may modify the test pr ocedures due to local conditions, as long as the intent of the test is still achieved.

9. Visual Inspections of Lightning Protection Systems. Inspect all visible parts of the system. Pulling or tugging on conductors and connections to insure soundness is a necessary part of these inspections, but be careful not to damage the system in the process. Visual/physical inspection must determine if:

9.1. The system is in good repair.

9.2. There are loose connections that might cause high resistance joints.

9.3. Corrosion or vibration has weakened any part of the system.

9.4. Down conductors, roof conductors, and ground terminals are intact.

AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003 11

9.5. Braided bonding wires are excessively frayed (cross sectional area reduced by half).

9.6. Ground wires on lightning protection masts are damaged by lawn mowers or other equipment.

9.7. Conductors and system components are securely fastened to mounting surfaces. Relocate con-nections as necessary to better protect against accidental displacement.

9.8. Additions or alterations to the protected structure require additional protection.

9.9. Surge suppression (overvoltage) devices appear damaged.

9.10. The system complies with applicable sections of NFPA 780, Standard for the Installation of Lightning Protection Systems (Attachment 4).

9.11. (Added-AFSPC) Ensure safety is not degraded to enhance aesthetic appeal of LPS system.

10. Visual Inspection of Facility Grounds. Unless otherwise specified by references in Table 1 ., con-duct visual inspections as follows. Inspect all visible and accessible parts of the system. Determine if they are in good condition and the installation meets NEC r equirements (Attachment 2). Typical items to check:

10.1. The system is in good repair.

10.2. There are no loose connections.

10.3. The system neutral is grounded at the service entrance (this includes the connection to the grounding electrode).

10.4. Separately derived systems are properly grounded.

10.5. Flashover protection is installed on insulating fittings on underground metallic pipelines enter-ing the facility.

10.6. Grounding systems within the facility are bonded together at ground level or below.

Section C— Grounding and Lightning Protection Requirements

11. Introduction. This section covers requirements for grounding and lightning protection systems, including systems installed on or in areas such as explosives buildings, magazines, operating locations and shelters. Use these requirements when inspecting to determine compliance and when repairing or modifying systems. See AFMAN 91-201, Explosive Safety Standards.

12. Testing and Inspecting Static and Lightning Protection Systems and Grounding:

12.1. Procedures. Use Attachment 4 and Attachment 5 as a guide for establishing proper mainte-nance procedures and a check during self inspections.

12.2. Inspection and Testing. Inspect the static and lightning protection systems and grounding for buildings and facilities visually and electrically according to Sections A, Maintenance Policy and B, Grounding Resistance and Continuity Tests and Visual Inspections, and the special requirements in this section.

12.3. Records. Keep records of test and inspections for explosives facilities for a minimum of six inspection cycles (see paragraph 4.). Figure 1. is an example sketch of a grounding and lightning pro-tection system with test points. 9

12 AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003

Figure 1. Example Sketch of Test Points (Typical).

13. Static Protection.

13.1. Equipment Grounding. The best methods to eliminate or reduce the hazard from static electric-ity are bonding and grounding. Bonding minimizes potential differences between conductive objects.

AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003 13

Grounding minimizes potential differences between objects and the ground. Inspect and test facilities for compliance with NFPA 77, Static Electricity, which contains the minimum acceptable static grounding and bonding requirements for Air Force activities, except as modified herein.

13.1.1. Bonding and grounding wires must be large enough to withstand me chanical damage.

Minimum size for existing bonds is AWG No. 8. Make repairs with wires no smaller than AWG No. 6 copper. Static grounds for portable or movable equipment must use braided cable for added flexibility.

13.1.2. Static grounds must be 10,000 ohms or less, unless otherwise stated. Static electricity cre-ates extremely small (milliamps) currents, so even this large resistance is small enough to bleed off static charges. But because the static gro unding system must be connected to the facility grounding system, resistances of less than 25 ohms are common.

13.2. Static Bus Bars. Static bus bars are usually 2- by 1/4-inch copper bars installed on the interior wall of the facility. Bond static bus bars directly to each lightning protection down conductor where it crosses the down conductor if separation between the two is within NFPA 780 bonding distance and the bus or down conductor cannot be relocated. They must also be connected directly to the facility grounding electrode system. See Attachment 6 for testing requirements. Use static bus bars only for static grounding. Do not connect telephone grounds, electrical conduit or intrusion systems to this bus. Static bus bars must not be used as a grounding medium for these systems. As a general rule, do not connect a static bus to any facility metal body or use this bus to ground structural components of a facility; however, coincidental connections of the bus bar through its anchoring/mounting system are acceptable as is the mounting of the s tatic bars on the skin of a m etal structure. Portable grounding straps from equipment to the static grounding bus are not real property. Visual inspections and conti-nuity checks for these straps are the responsibility of the user.

13.3. Belting Requirements. On equ ipment such as be lt-driven compressors and conveyor belts, if static electricity is a hazard, use non-st atic-producing belting. B elting must have a r esistance not exceeding 1,000,000 ohms when measured according to IEEE STD 142, chapter 3.

13.4. Conductive Floor Grounds. If the facility requires conductive floors, the resistance of the floor must be less than 1,000,000 ohms. Additionally, the resistance between the floor and ground connec-tions must not be less than 25,000 ohms. This requirement protects personnel from electric shock haz-ard and allows bleed off of static buildup in people and operating equipment. See Attachment 6 for testing requirements. The testing and using agency must keep a record of test results.

14. Lightning Protection Systems. AFMAN 91-201 identifies explosives facilities that r equire light-ning protection systems. Many other structures housing critical or sensitive supplies or equipment also require protection. The following requirements may be used as a guide for facilities that require lightning protection.

14.1. General. Systems must comply with NFPA 780 and AFM 88-9, Chapter 3, Electrical Design Lightning and Static Electricity Protection (except as modified herein). Early streamer emission sys-tems or charge dissipation systems are not permitted. Parts and materials must carry the Underwriters Laboratories (UL) label or equivalent. Otherwise, such components must be a pproved by the MAJ- COM electrical engineer in charge of lightning protection. Facilities in foreign countries may use host nation codes and standards if they offer equivalent protection, as determined by the MAJCOM electri-cal engineer with concurrence from HQ AFCESA/CESE and approval of the DoD Explosive Safety

14 AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003

Board (DDESB). Otherwise, the Status of Forces Agreement (SOFA) must permit their use. Where the SOFA requires compliance with host nation codes, translate those required codes into English, make them available to all appr opriate personnel, and per form necessary training. Maintain all installed systems according to this instruction. If not required, remove the system with coordination through the using agency.

14.1.1. (Added-AFSPC) New Construction. Facilities shall be designed with:

14.1.1.1. (Added-AFSPC) Ground wells at c orner ground rods. This will pr ovide easy access to the corner ground rods for more convenient testing.

14.1.1.2. (Added-AFSPC) U.L listed high compression or exothermic-weld type connec-tors providing they are commercially available. This will provide for a high degree of mechanical and electrical integrity for connections.

14.2. Bonding Requirements. Adequate bonding is more imp ortant than grounding. Bonding ensures all metallic objects are at equal potentials, preventing dangerous flashovers. Inspect and test facilities for compliance with NFPA 780 and Attachment 3 of this instruction.

14.3. Grounding Resistance. Low resistance is desirable but not essential for lightning protection.

For most facilities, resistance to ground should be less than 25 ohms. If this cannot be achieved where only ground rods are used (no ground loop conductor), install a ground loop conductor. The resistance to ground of a ground loop system is acceptable even if greater than 25 ohms. See Attachment 2.

14.4. Lightning Protection For Explosives Facilities. Use the basic practices in Attachment 4, with the following additions:

14.4.1. The system must be designed for a 30.5-meter (100-foot) striking distance.

14.4.2. Installation of ground wells (hand holes) at corner ground rods is recommended to aid access for testing.

14.4.3. Replace existing bolted connectors on down conductors and roof conductors needing repair with high compression or exothermic-weld type connectors. Connections to air terminals are an exception, but they must be tight and in good repair. Bolted connections to aluminum bod-ies (such as vents) and to metal bodies for the purpose of bonding are also acceptable. Brazing to metal bodies is allowed but not recommended due to the possibility of a cold weld with inadequate strength.

14.4.4. Structural elements of a facility may serve as air terminals, down conductors, or the earth electrode.

14.5. Explosives Facilities with Large Perimeters. New explosives facilities (including igloos) with a perimeter over 91.4 meters (300 feet) that require lightning protection and do not use the structural steel as the air terminals must use either a mast system or an overhead wire system. See Attachment 4 for requirements. Since these systems provide better protection, and maintenance is easier, consider using this type of protection for other kinds of facilities. The MAJCOM may waive this requirement (overhead or mast system).

14.6. Protective Aircraft Shelters (PAS) (also known as Hardened Aircraft Shelter (HAS)). PASs with interior steel arches or interconnected rebar (i.e., floor rebar that is connected to wall rebar) and grounded ventilators of metal at least 4.78 millimeters (0.188 inch) th ick do not need air t erminals.

Metal ventilators less than 4.78 millimeters (0 .188 inch) thick must be protected by an ai r terminal.

AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003 15

All metal bodies in the PAS must be properly bonded and grounded. See Attachment 3. An adequate grounding system is also required.

14.7. (Added-AFSPC) Lightning Protection For Above Ground Launch Structures. Above ground launch structures shall be provided the same protection as explosive facilities (see para-graph 14.4. in AFI32-1065, Grounding Systems) with the following additions.

14.7.1. (Added-AFSPC) The system w ill be desi gned in accordance with NFPA 780, AFI32-1065, and this supplement. Base the design on top 100 feet of the structure.

14.7.2. (Added-AFSPC) All structural metal shall be bonded.

14.7.3. (Added-AFSPC) When practical, structural steel members will be made electrically continuous and used as down conductors.

14.7.4. (Added-AFSPC) The structure will have an interconnecting ring conductor installed every 200 feet in height when the structural members do not form a ring every 200 feet. In some cases it will be necessary to attach temporary conductors between the fixed and move-able portions of the launch structure to ensure potential equalization.

14.7.5. (Added-AFSPC) All antennas, radomes, and dishes m ounted external to the struc-ture will have surge suppression installed where the conductor enters the launch structure.

15. Surge Protection.

15.1. Entering or exiting metallic power, intrusion detection, communication antenna, and instrumen-tation lines must have surge protection sized for lightning surges to reduce transient voltages to a harmless level. Install the surge protection as soon as practical where the conductor enters the interior of the facility. Devices commonly used for this include metal oxide varistors, gas tube arresters, and transzorbs. The lines must enter the facility in shielded cables or metallic conduits run underground for at least 15.24 me ters (50 feet) from the facility. The antenna leads from antennae on the facility and within the zone of protection do not have to go underground.

15.2. Steam, water, and air conditioning lines must be bonded to the facility's lightning protection system before entering the structure. For explosive facilities, all metallic utility lines must run under-ground for at least 15.24 meters (50 feet) from the facility.

WILLIAM P. HALLIN, Lt General, USAF DCS/Installations & Logistics

16 AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003

Attachment 1

GLOSSARY OF REFERENCES AND SUPPORTING INFORMATION

References

DoD Publications

DoD 6055.9-STD, Ammunition Explosives Safety Standards

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

Federal Information Processing Standards (FIP) Pub 94, Guidelines on Electrical Power for ADP Instal-lations. (Available from National Technical Information Center, US Department of Commerce, Spring-field VA 22161.)

Air Force Publications

AFI 32-1063, Electrical Power Systems

AFI 41-203, Electrical Safety in Medical Treatment Facilities

AFMAN 91-201, Explosive Safety Standards

AFJMAN 32-1082, Facilities Engineering, Electrical Exterior Facilities

AFM 85-16, Maintenance of Petroleum Systems

AFM 88-9, Chapter 3, Electrical Design Lightning and Static Electricity Protection

AFOSH STD 91-38, Hydrocarbon Fuels

Other

ANSI C2, National Electrical Safety Code (IEEE). (Copies available from The Institute of Electrical and Electronics Engineers, 345 East 47th Street, New York NY 10017.)

DNA-A-86-60, V1-3, DNA EMP Engineering Handbook for Ground-Based Facilities

*IEEE STD 142, IEEE Recommended Practice for Grounding for Industrial and Commercial Power Sys-tems (Green Book)

*IEEE STD 446, Recommended Practice for Emergency and Standby Power (Orange Book)

**NFPA 70, The National Electrical Code

**NFPA 77, Static Electricity

**NFPA 99, Standard Health Care Facilities

**NFPA 780, Standard for the Installation of Lightning Protection Systems

Additional References

*IEEE S TD 81, IEEE Guide for Measuring Earth Resistivity, Ground Impedance, and Earth Surface Potentials of a ground System

*IEEE STD 1100, IEEE Recommended Practice for Powering and Grounding Sensitive Electronic Equip-ment (Emerald Book)

AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003 17

*Available from The Institute of Electrical and Electronic Engineers, 345 East 47th Street, New York NY 10017.

**Available from National Fire Protection Association, 1 Batterymarch Park, Quincy MA 02269-9990.

Abbreviations and Acronyms

ANG—Air National Guard

ANSI—American National Standards Institute

AWG—American wire gauge

BBF—basic bonding formula

DDESB—Department of Defense Explosive Safety Board

DoD STD—Department of Defense Standard

EMP—electromagnetic pulse

FIPS—Federal Information Processing Standard

IEEE—Institute of Electrical and Electronics Engineers

IG—isolated ground

LOX—liquid oxygen

MAJCOM—major command

MIL HDBK—Military Handbook

MOV—metal oxide varistor

NBN—no bonding needed

NEC—National Electrical Code

NFPA—National Fire Protection Association

PAS—Protective Aircraft Shelter (also known as Hardened Aircraft Shelter (HAS))

POL—petroleum, oils, lubricants

PMEL—Precision Measurement Equipment Laboratory

SDS—separately derived system

SOFA—Status of Forces Agreement

T.O.—Technical Order

WS3—Weapon Storage and Security System

Terms

Air Terminal—The component of the lightning protection system intended to intercept lightning flashes, placed on or above a building, structure, or tower. A building's grounded structural elements may be used as an air terminal. Sometimes air terminals are referred to as lightning rods.

18 AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003

Bonding—An electrical connection between an electrically conductive object and a component of a lightning protection system that is inte nded to significantly reduce potential differences created by lightning currents.

Conductor, Bonding—A conductor used for equalization potential between metal bodies and the lightning protection subsystem.

Catenary System—A lightning protection system consisting of one or more overhead wires. Each overhead wire forms a catenary between masts, and serves the function of both a strike termination device and a main conductor.

Conductor, Main—A conductor intended to carry lightning currents from the point of interception to ground terminals.

Copper Clad Steel—Steel with a coating of copper bonded on it.

Down Conductor, Lightning—The conductor connecting the roof conductors or overhead ground wire to the earth ground subsystem.

Ground Loop—A conductor, buried 3 to 8 feet from a structure, encircling the structure interconnecting ground electrodes. The conductor may be connected to buried copper or steel plates or ground rods.

These are installed to establish a low resistance contact with earth. (Also referred to as counterpoise, loop conductor, or closed loop systems.)

Facility Ground System—The electrical ly interconnected system of conductors and conductive elements that provides multiple current paths to earth. The facility ground system can include the earth electrode subsystem, lightning protection subsystem, signal reference protection subsystem, fault protection subsystem, static ground subsystem, as well as the building structure, equipment racks, cabinets, conduit, junction boxes, raceways, duct work, pipes, and other normally non-current-carrying metal elements.

Ground—The electrical connection to earth primarily through an earth electrode subsystem. This connection is extended throughout the facility by the facility ground system.

Ground Terminal—The portion of a lightning protection system such as a ground rod, ground plate, or ground conductor that is installed for the purpose of providing electrical contact with the earth.

Inherent Bond—Where metal bodies located in a steel-framed structure are electrically bonded to the structure through the construction.

Integral System—A system which uses air terminals mounted directly on the structure to be protected.

Lightning Protection System—A complete system consisting of components (such as air t erminals, interconnecting conductors, ground terminals, surge suppression devices, and other connectors or fittings) and subsystems required to assure a lightning discharge will be safely conducted to earth.

Mast System—A lightning protection system using masts that are remote from the struc ture to provide the primary protection from a lightning strike.

Overhead Wire System—System using conductors routed over the facility, at a specified height, designed to provide the required zone of protection. Also known as overhead shield wire system and catenary system.

Side Flash—Electrical arcing between metal objects caused by difference of potential from a lightning discharge.

AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003 19

Strike Termination Device—A component of a li ghtning protection system intended to intercept lightning flashes and connect these fl ashes to a path to ground. Strike termination devices include air terminals, masts, permanent parts of structures, and overhead wires in catenary systems.

TEMPEST—Unclassified name for investigation/study of compromising emanation.

Zone of Protection—Space below and adjacent to a lightning protection subsystem that is likely to avoid direct lightning discharges.

20 AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003

Attachment 2

BASIC REQUIREMENTS FOR GROUNDING SYSTEMS

A2.1. Types of Grounds. There are five basic types of grounding systems which must be inspected if present in a facility: static grounds, equipment grounds, electrical system grounds, lightning grounds, and signal reference grounds.

A2.1.1. Static Grounds. A static ground is a connection between a piece of equipment and earth to drain off static electricity charges before they reach a sparking potential. Typically, static grounding involves connecting large metal objects such as fuel tanks or aircraft to earth through a ground rod.

Static grounds are not part of an electrical power system. But if an equipment grounding conductor is adequate for power circuits, it is also adequate for static grounding.

A2.1.2. Equipment Grounds. Equipment grounding involves interconnecting and connecting to earth all non-current-carrying metal parts of an electrical wiring system and equipment connected to the system. The purpose of grounding equipment is to ensure personnel safety by reducing any charge in an equipment item to nea r zero volts with respect to ground. Equipment ground must be c apable of carrying the maximum ground fault current possible without causing a fire or explosive hazard, until the circuit protective device clears the fault. An example is the bare copper wire or green insulated conductor connected to the frames of electric motors, breaker panels, and outlet boxes. The equip-ment ground is connected to a n electrical system ground (neutral) only at the electrical service entrance of a building and should not exceed 25 ohms to ground.

A2.1.3. Electrical System Ground. The purpose of electrical system grounds is to stabilize voltage to ground and give a low impedance path for fault currents. One wire or point of an electrical circuit in an electrical system ground is connected to earth. This connection is usually at the electrical neutral (though not always), and is called the "system ground." Examples of electrical system grounds are generator or transformer neutral points connected to earth, and the grounded neutral of an interior wir-ing system. The resistance of most electrical system grounds below 600 Vac should not be more than 25 ohms. Medium voltage systems (1-15kV) frequently are grounded through a resistor (or reactor) and may exceed 25 ohms. This limits ground fault current to a manageable level.

A2.1.4. Lightning Grounds. The purpose of lightning grounds is to safely dissipate lightning strokes into the earth. They are part of a lightning protection system which usually includes air terminals (lightning rods), down conductors, arresters, and other connectors or fittings required for a complete system. The sole purpose of a lightning protection system for a facility is to protect the building, its occupants, and contents from the thermal, mechanical and electrical effects of lightning.

A2.1.5. Signal Reference Grounds. The purpose of a signal reference ground is to provide a low impedance signal reference system for electronic equipment to minimize noise-induced voltages and thereby reduce equipment malfunctions. Common configurations include planes and grids. See FIPS Pub 94, Guidelines on Electrical Power for ADP Installations, for details.

A2.1.6. Subsystem Grounds. Each of the grounding systems described above may be a subsystem of a total facility grounding system. All grounds (and subsystems) must be bonded together according to NFPA 780 and NFPA 70, The National Electrical Code. MIL-HDBK-419A contains example sketches of grounding subsystem interconnections.

AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003 21

A2.2. NEC Grounding Requirements. Electrical systems and circuit conductors are gr ounded to l imit voltages during lightning and to facilitate overcurrent device operation in case of a ground fault. The NEC allows the system neutral to be grounded and limits the location of this neutral to earth connection to the source side of the se rvice entrance disconnect or at a separately derived system (NEC, articles 250-23 and 250-26). Since the neutral will carry current under normal operating conditions, the NEC often refers to it as the grounded conductor. If a building service is at less than 1000 volts, a neutral con-ductor (if required by NEC, article 250-5) must be run to each service entrance from the servicing trans-former and bonded to the disconnecting panel enclosure. In contrast to the neutral, the equipment ground conductor (green insulated or bar e wire) is referred to as the grounding conductor. The grounding con-ductor is used to ground metallic enclosures and motor frames, and must be connected to neutral only on the source side of the service entrance disconnect.

A2.2.1. Facility Ground. The NEC requires a premises wiring system to have a grounding electrode at each service. This electrode may be of several different types or systems. Each of the types listed below must be bonded together to form the grounding electrode system. Where none of the listed electrodes are present, ground rods or ground plates must be used. Ground rods must be at least 2.44 meters (8 feet) in length (10 feet for lightning protection; see Attachment 4) and no closer than 1.83 meters (6 feet) from other rods or plates. Ground rods or plates must not be aluminum. The Air Force also prohibits stainless steel ground rods.

A2.2.1.1. Where a metal underground water pipe (uncoated) is in direct contact with the earth for

3.05 meters (10 feet) or more, do not bond around insulation flanges installed for cathodic protec-tion. If the underground water pipe is the only electrode available, ground rods must supplement it.

A2.2.1.2. The metal frame of a building where the building is effectively grounded.

A2.2.1.3. An electrode encased by at least 51 millimeters (2 inches) of concrete, made of at least

6.1 meters (20 feet) of one or more steel reinforcing bars, located within and near the bottom of a concrete foundation or footing in direct contact with the earth. This is known as a Ufer ground.

A2.2.1.4. A ground ring encircling the building at least 0.76 meters (2.5 feet) deep. The ground ring must be at least 6.1 meters long and use at least AWG No. 2 copper (1/0 copper for lightning protection ground ring conductor; see Attachment 4).

A2.2.2. Separately Derived Systems (SDS). A separately derived system is a premises wiring system where power is derived from a generator, transformer, or converter. An SDS has no direct electrical (metallic) connection, including the ne utral, to the sup ply conductors originating in another system.

The neutral of an SDS must be connected to a nearby grounding electrode. In order of preference, this grounding electrode may be building steel, grounded water pipe, or a separate ground rod. The equip-ment grounding conductor (green wire) is bonded to the neutral at this point only. A ground rod can be used only when other types of grounding electrodes are not available. All grounding electrodes must be connected to the facility grounding systems.

A2.2.2.1. Dry type transformers (isolation and non- isolation) are common sources of SDSs i n a facility. Usually, they are connected in a de lta-wye configuration. SDS transformers are widely used in sensitive electronic installations (computer power distribution centers are essentially SDS transformers), since they effectively establish a local ground at the electronic equipment. This minimizes the impedance to ground as seen by the load.

22 AFI32-1065_AFSPCSUP1 3 FEBRUARY 2003

A2.2.2.2. Standby or emergency generators are also common sources of separately derived sys-tems. However, a genera tor connected to a facility thro ugh a transfer switch is not a separately derived system if the neutral conductor remains connected to the normal commer cial power source neutral after transfer (the neutral is not switched along with the phase conductors). In this case, the required c onnection of the neutral to the facility's grounding electrode system for both the commercial power source and the generator must be made only on the supply side of the com-mercial power service disconnect. Providing an additional connection between the generator neu-tral and a grounding electrode at the generator would be a grounding connection on the load side of the service disconnect and a violation of the NEC. Refer to IEEE Standard 446, Recommended Practice for Emergency and Standby Power (The Orange Book), for additional information and requirements on grounding emergency and standby generators.

A2.3. Grounding Electrodes:

A2.3.1. Connection To Earth. The most practical method of connecting to earth is to bury a solid body, such as a metal rod, pipe, or sheet, and connect a grounding conductor to it. This solid body is known as a grounding electrode.

A2.3.2. Methods for Obtaining Better Grounds. Frequently a satisfactorily low electrode resistance cannot be obtained because of high soil resistivity. Use the following methods if it is necessary to lower the resistance of the electrode.

A2.3.2.1. Deeper Rod. As a rod is driven more deeply into the soil, it not only has more surface contact with the ea rth, but it also begins to reach soil which is more conduc tive. The deeper the electrode, the less the effect of surface moisture content and temperature changes.

A2.3.2.2. Parallel Ground Rods. Rods driven in parallel to each other should have space between them at least the length of the rods. Multiple rods connected by a conductor have a greater ability to equalize potential over the installation area.

A2.3.2.3. Soil Replacement. You can significantly lower the resistance of a ground rod by lower-ing the resistivity of the soil immediately surrounding it. Use a mixture of 75 percent gypsum, 20 percent bentonite (well driller's mud), and 5 percent sodium sulfate.