Static Electricity - hdbk109220040066

DOE-HDBK-1092-2004

evacuated during electrical storms. Specific operations shall be assessed for the risk of

detonation of explosives by lightning. Such assessment shall consider the need for the

protection factors outlined in Appendix I, NFPA 780. When risk is high, as in operations with

highly sensitive electrostatic materials or components, operations shall be conducted only in

lightning-protected facilities. Approved lightning protection systems shall conform with the

requirements of Appendix I, NFPA 780.

Lightning-protection systems should be visually inspected every 7 months and a report on their

conditions filed at least annually. Any evidence of corrosion, broken wires or connections, or any

other problem that negates the system's usefulness shall be noted and the problem repaired.

Lightning protection systems should be tested electrically every 14 months to ensure testing

during all seasons, or immediately following any repair or modification. The testing shall be

conducted only with instruments designed specifically for earth-ground system testing. The

instruments shall be able to measure 10 ohms 10% for ground resistance testing and 1 ohm

10% for bonding testing. Electrical resistance readings shall be recorded.

Inspection records shall contain the most recent electrical test report and any subsequent visual

inspection reports for each building with a lightning-protection system.

5.1.4

STATIC ELECTRICITY

Static electricity shall be controlled or eliminated in areas where materials are processed or

handled that are ignitable by static spark discharge. This category includes spark-sensitive

explosives, propellants, and pyrotechnics, as well as solvent vapors and flammable gases.

Approved systems to dissipate static electricity shall conform to the requirements of NFPA 77

and IEEE 142.

5.1.4.1 BONDING AND GROUNDING EQUIPMENT

Bonding straps shall be used to bridge locations where electrical continuity may be broken by

the presence of oil on bearings, or by paint or rust at any contact point. Permanent equipment in

contact with conductive floors or tabletops is not considered adequately grounded. Static

grounds shall not be made to gas, steam, or air lines; dry-pipe sprinkler systems; or air

terminals of lightning protection systems. Any ground that is adequate for power circuits or

lightning protection is more than adequate for protection against static electricity.

5.1.4.2 TESTING EQUIPMENT GROUNDING SYSTEMS

Grounding systems shall be tested for electrical resistance and continuity when installation is

complete and, in the case of active equipment, at intervals to be locally determined. The

grounding system shall be visually inspected for continuity before it is reactivated if the

equipment has been inactive for more than 1 month. All exposed explosives or hazardous

materials shall be removed before testing. During a test for resistance to ground, all equipment,

except belt-driven machines, shall be considered as a unit. In measuring the total resistance to

ground for belt-driven machinery (to ensure compliance with Section 5.1.4.3), resistance of the

belt is to be excluded. All conductive parts of equipment shall be grounded so that resistance

does not exceed 25 ohms, unless resistance is not to exceed 10 ohms because of the lightning

protection system. For existing equipment, the rate of static electricity generation shall be

considered before changes are made in grounding systems. The resistance of conductive

rubber hose shall not exceed 250,000 ohms.

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