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NOTE: Many of the messages you see displayed here indicate a fault with your system that may require immediate attention and service. Contacting your fire equipment service provider, a certified fire alarm technician or a qualified electrician would be the prudent thing to do.

LOOP TROUBLE (also may display as "LOOP 1", "LOOP 2", "LOOP 3" followed by the word "TROUBLE" and/or "OPEN" or "SHORT"):

A condition which may be caused by an interruption of the data communication link (or signalling line circuit) caused by either an "open" circuit, "short" circuit, or device failure. If an "open", additional troubles may also be queued that relate to the failure of one or more active field devices from communicating their condition with the common control.

BASE SIGNAL TROUBLE (also may display as "NAC CIRCUIT FAULT" and may also identify a circuit or module number):

A fault on a bell or output circuit may display a variety of specialized messages in addition to the basic trouble message. A "short" or "open" condition may also be identified.


Usually indicates a specific problem related to the condition of the stand-by power supply or battery. It could indicate a blown fuse, tripped resettable breaker, non-functional charger, disconnected or faulty battery.

GROUND FAULT (also may display as "EARTH FAULT"):

A condition in which an alarm system references a structure's common ground plane. This can be caused by a wire to an INPUT or OUTPUT DEVICE that is "pinched" or been abraded so as to contact the metal backbox (or conduit). In the latter instance, the wire can become abraded (skinned) during the installation process exposing the bared conductor(s). In some systems a fault condition can be artificially generated when the wiring is incorrectly terminated or when multiple power supplies with no common connection are involved. Another frequent cause of a "Ground Fault" is water ingress at a field device such as a ceiling mounted smoke or heat detector. Ground faults are not difficult to pinpoint but often present a challenge to the servicing technician when more than one are present on a system or if the fault is intermittent (as may be the case for water ingress).

SHORT FAULT (also may display a "LOOP" or "SIGNAL" or "NAC" followed by a number identifier):

A wire to wire short circuit will often result in a display like this.


See LOOP TROUBLE. This may also indicate a problem with the onboard UDACT or, in the case of a stand-alone communicator, may indicate a signal transmission failure to the central monitoring facility.

AC LOSS (also may display as "POWER BROWN-OUT" or "AC FAIL"):

Indicates a loss of primary power to the common control. This may be caused by a tripped main breaker or local power failure. In rarer instances, the loss of the power supply's transformer will also result in the same indication.

DATA LOOP TROUBLE (also may display as "DATA FAULT"):

See LOOP TROUBLE. On some systems this may also indicate a CPU FAULT.

CPU FAULT (may also display as "CPU FAILURE"):

Indicates a critical fault has occurred with the common control's main processor. This usually requires replacing the system's main board assembly and reloading the operating system from an archived back-up.


This message is peculiar to mostly Edwards (now Chubb-Edwards) common controls that employ Signature series addressable devices. The message will display if you move an addressable module or install a new one, and can appear if you replace an existing unit. The map error message will also include a number identifying the loop controller (or data card) on which the fault appears.  Normally the system will "re-identify" the module you replaced (as long as it's the same type as the old one) and the trouble should clear. If it doesn't, then you'll have to call for service (removing the message will involve reprogramming the system).




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