~ National Lightning Safety Institute ~

Section 1.4.5

Presented at the International Lightning Detection Conference, Broomfield, Colorado, April 2-4, 2012

1. Abstract

The Department of Defense Explosives Standards Board (DDESB) was established following the July 10, 1926 lightning visit at the Lake Denmark Powder Depot at Picatinny Arsenal, NJ. An assumed "lightning-protected" magazine with 600,000 pounds of TNT was set off. Four days of explosions followed with 19 persons killed and 38 wounded.

Two years later, Congress mandated DDESB to have oversight for every aspect of explosives under control of the US Armed Forces. Since 1926, some 82 known lightning-caused explosions to federal government facilities have occurred. DDESB and the military services inspect military explosives stores for code compliance:

• Civilian code: NFPA-780
• Army code: PAM 385-64
• Navy code: NAVSEA OP5
• USAF codes: AFI 32-1065 and AFMAN 91-101
• DDESB standard: 6055.9

2. Code Details for Lightning Safety

Code details for lightning safety are contained in NFPA 780, Standard for the Installation of Lightning Protection Systems, version 2011. Chapter 8 addresses Structures Housing Explosives Materials.

Caveat: Absolute safety from lightning is impossible due to the chaotic and unpredictable nature of atmospheric electricity discharges.

Mandate: Code compliance is required.

Elements of lightning protection include:

1. Air Terminals. Rods, masts, or grounded wires are connected to an earth reference.
2. Dedicated wire conductors or building steel connect air terminals to ground.
3. Bonding of all adjacent conductive objects assures an equi-potential reference.
4. Grounding. Lightning requires a low impedance earth destination. Volumetric efficiencies are essential.
5. Surge protection provides defenses for electrical power and signal/data lines.
6. Inspection, maintenance, and testing of the system by certified and qualified personnel for lightning protection system functionality assurance.

3. Conclusion

Lightning protection of explosives storage facilities is mandated by Armed Forces codes, such as Air Force AFI 32-1065, Navy NAV OP SEA 5, and Army PAM 385-64. Personnel responsible for compliance must attend approved lightning protection systems courses and received the required certificates of completion. DDESB may suspend explosives handling activities until lightning protection system deficiencies are corrected.