Abstract: An equipment security system is provided herein which is capable of monitoring at least one security loop for detecting unauthorized removal of equipment interconnected within the security loop by means of a connecting member comprises a predetermined resistance secured in or to the equipment forming the security loop, that resistance being one arm of a resistance bridge. Such predetermined resistance has a resistance value sufficient to maintain the resistance bridge in a substantially-balanced state. The resistance bridge has a DC voltage permanently applied across one of its two pairs of diagonal terminals and has a diode bridge connected across the other of its two pairs of diagonal terminals. Means are responsive through the diode bridge for indicating an unbalanced state of the resistance bridge to indicate interruption of the security loop, thus enabling the alarm or warning system.