Humidification to prevent accumulations and subsequent discharges of static electricity is usually effective if the relative humidity is above 60%. However, certain materials such as metallic powders and some pyrotechnic mixtures cannot be exposed to air with 60% relative humidity because of the possibility of their spontaneous ignition. Where this technique is used to prevent accumulations of static electricity, a daily check of the humidity levels will be performed before work starts.

5.1.4.7 GROUND-FAULT CIRCUIT INTERRUPTER

Ground-fault circuit interrupter (GFCI) protection shall be provided in static-grounded areas where personnel are using hand-held, portable, ac-powered electrical equipment operating at 120 V.

5.1.5 ELECTRICAL EQUIPMENT AND WIRING

Electrical equipment and wiring in locations containing explosives shall comply with relevant provisions of the NEC and DOE regulations, plus the requirements in this section.

Figure 5-1. Testing shoes on wearer.

5.1.5.1 PERMANENT EQUIPMENT AND WIRING

The NEC and this section are minimum requirements for DOE facilities containing explosives. Though the NEC does not specifically address explosives, Article 500, "Hazardous (Classified) Locations," does establish requirements for the design and installation of electrical equipment and wiring in locations containing combustible dusts and flammable liquids, vapors, or gases that in general are comparably hazardous. All permanent electrical equipment and wiring in work areas containing explosives hazards shall conform to the standards of the NEC Hazardous Locations Class II or Class I and II (dual rated). For Class II installations, provisions should be made for easy conversion to Class I.