The invention comprises of a method and alarm device used to prevent metal theft from irrigation systems. The alarm device attaches to a plurality of electric conductor such as copper wiring that is in need of protecting and the preexisting irrigation system circuit. The alarm device detects voltage in the irrigation system circuit and if there is no voltage signals from the irrigation system circuit, then the alarm device automatically breaks the original circuit and inserts itself into the irrigation system circuit. The alarm device then sends a low voltage, low current down the plurality of electric conductors and the plurality of conductors then become part of a circuit that energizes a magnetic switch located in the alarm device. A breach of integrity of the plurality of conductors such as by physical detachment triggers an alarm condition which lead to audio and visual alarms plus activating an automated dialer.