US Patent 7253733 Cable lock system

A cable alarm system is provided that includes: a lock; a cable coupled to the lock and operative to conduct a current; a secondary wire coupled to the lock and parallel to the cable and operative to conduct a current; a current detector coupled to the cable and the secondary wire, operative to detect an interruption of a current in at least one of the cable and the secondary wire; a battery operative to supply power to the current detector; an alarm coupled to the current detector and receiving power from the battery; and a heat sensor coupled to the cable and the secondary wire.