A fireguard circuit for a power cable, which comprises a power line, a neutral line and a metal sheath surrounding the power line and the neutral line, includes a switch located in one of the lines. A solenoid sets the switch in either an open position or a closed position. A first silicon controlled...http://www.google.fr/patents/US7525777?utm_source=gb-gplus-shareBrevet US7525777 - Fireguard circuit
