Tamper circuit

Here we see an alarm system which incorporates a tamper circuit. Any break in this loop will cause an activation with the system switched on or off.

 
How this works in practice is seen in the next diagram. A four core cable is used so that both the detection loop and the tamper loop are contained in the one cable. This means that cutting this will result in the alarm activating in the on or off state. This tamper circuit is also connected to switches on the covers of all the detection devices, the control panel, cable junction boxes, the bell box, in fact emery cable run in an alarm system will have a tamper loop.