EMP protective systems

A representative electromagnetic pulse from a high altitude burst will typically have maximum field strengths near the ground on the order of 50 KV/meter and a time duration on the order of a microsecond and rise times on the order of 10 nanoseconds. Installation of EMP protective measures as a retrofit to existing installations is more costly that would have been required if included in the original design and construction. A basic approach for EMP protection of small city, county and State facilities includes containment of communications equipments in a minimus size, double layer galvanized steel wire mesh enclosure, with operators and hand sets adjacent to or remote from the shielded enclosure with connecting cables run in ferrous conduit with threaded couplings. Power cables should be contained in ferrous conduit and there should be a single panel entry of power, hand sets, control, and antenna cable conductors.