TROUBLE FAULT (or COMMON TROUBLE SIGNAL): A trouble condition or trouble light on a fire alarm or security system indicates a condition that might adversely affect the proper operation (or actually compromises part) of the system. The loss of primary power, back-up power, or a wiring problem (such as a cut or an abrasion which might ground a circuit in a back box) are all common "trouble" indications. "Trouble" conditions usually self-restore (that is the system returns to a "normal" state once the trouble has been cleared). A trouble on an input zone may prevent detectors in the circuit from functioning. It is extremely important that system TROUBLES be corrected as soon as possible.