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 ft 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.

Table 5-1. Quantity-distance separation for protection of underground service installation a,b

5.1.5.4 BUILDING SERVICE ENTRANCE

The electrical service entrance for explosives facilities shall be provided with:

1. An intermediate, metal-oxide surge lightning arrester on the primary side of the transformer per ANSUIEEE C62.11.

2. Surge arresters and surge capacitors on the supply side of the main service disconnect.

3. Interconnected grounding between the lightning arrester, surge arrester, surge capacitors, service entrance ground, and building ground.