Electrical Supply Systems

DOE-HDBK-1092-2004

exotherm of the explosive as determined by the differential thermal analysis test or the

differential scanning calorimetry test. When NEC Class I or II equipment is not available, the

substitute equipment shall be purged or sealed to prevent explosives contamination, shall

be determined intrinsically safe by facility management, or shall be administratively

controlled. If the equipment is purged, it shall be monitored for flow.

6. Areas that contain explosives that are not defined as hazardous locations (areas containing

no dust, vapor, gas hazards, or exposed explosives; for example, storage magazines), shall

be evaluated and documented by facility management to ensure that electrical ignition

sources are minimized or shall be regarded as NEC Class II.

7. Procedures shall be established by each DOE facility to control the use and modification of

electrical equipment in explosives areas and ensure that uniform standards are adhered to

throughout the facility.

5.1.5.3 ELECTRICAL SUPPLY SYSTEMS

There may be multiple hazards where explosives facilities are located near electrical supply

lines. To protect against these hazards, the NESC (ANSI/IEEE C2) and the following

requirements apply to all new construction or major modification and should be considered for

existing facilities:

1. Electric lines serving explosive facilities shall be installed underground from a point not less

than 50 feet from such facilities. This also applies to communications and instrumentation

lines and security alarm systems.

2. Electric service lines required to be close to an explosives facility shall be no closer to that

facility than the length of the lines between the poles or towers supporting the lines, unless

an effective means is provided to ensure that broken, energized lines cannot come into

contact with and present a hazard to the facility or its appurtenances.

3. Unmanned electrical substations shall be no closer to explosives facilities than public traffic

route distances.

4. Electric transmission lines (carrying 69 kV or more) and the tower or poles supporting them

shall be located not closer to explosives than:

a. Inhabited-building distance if the line in question is part of a system serving a large, offsite

area.

b. Public traffic route distance if loss of the line shall not create serious social or economic

hardships.

c. Underground utility separation distance criteria found in Table 5-1.

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