Fire Alarm Panel Showing a Fault? What the Common Messages Mean

A fault is not a fire, but it is not nothing

When a fire alarm panel shows a fault, the yellow fault light comes on and the panel buzzes. The building is not on fire, and the alarm will usually still work in most areas. But some part of the system, a detector, a sounder, a cable or the power supply, is not doing its job, and that part may stay silent in a real fire.

Under the Regulatory Reform (Fire Safety) Order 2005 the responsible person has to keep the system in working order. In practice that means writing the fault in the logbook, getting it looked at promptly, and not leaving it showing for weeks because the buzzer has been silenced.

What you can safely do yourself

Before calling anyone, a few minutes at the panel saves time and often tells an engineer exactly what to bring.

• Read the display and write down the exact message, including any zone, loop or device number it gives.
• Silence the buzzer at user level. This stops the noise without hiding the fault.
• Check the logbook and ask around: decorators, electricians or cleaners working near a detector are a very common cause.
• Find the fire alarm isolator or circuit breaker, normally labelled Fire Alarm, Do Not Switch Off. If it is off, find out why before switching it back on, and do not keep resetting a breaker that trips again.
• If the system is monitored by an alarm receiving centre, let them know there is a fault.
• Do not open the panel, and do not disable zones or devices just to make the fault go away. A disabled zone is a part of the building with no fire detection.

Mains fail

The panel has lost its mains supply and is running on its standby batteries. The usual causes are the fire alarm breaker or isolator being switched off, a tripped RCD, or a blown fuse inside the panel. The batteries keep the system running for about a day, so this is urgent rather than an emergency, but it needs sorting the same day if possible.

Battery fault or charger fault

The standby batteries are past their life, have a loose connection, or the charger board has failed. Batteries in a fire panel normally last around four years. They are always replaced as a pair, never one at a time, and the charger is checked at the same time.

Earth fault

Somewhere a fire alarm cable is touching earth. Typical causes are water getting into a detector base or an outside sounder, a cable damaged during building work, or a screw or nail driven through a cable. Earth faults can be hard to find, because the panel only knows the fault is somewhere on the system. An engineer splits the circuit at isolators or junctions and measures each section until the faulty part is found.

Open circuit or short circuit

An open circuit means the wiring has been broken: a cable cut, a detector head taken off its base, or an end-of-line device missing. A short circuit means two conductors are touching, often from crushed cable or water. On an addressable system the loop isolators limit the damage to one section, and the panel shows which devices have stopped responding, which narrows the search a great deal.

Device missing, not responding or double address

The panel has lost contact with one device. Most often a detector head has been taken off, by decorators covering it or by someone stopping a false alarm, or a replacement device was fitted without being addressed. A double address means two devices have been given the same number after a change. These are usually quick to put right once the device is found.

Dirty detector, pre-alarm or drift

Many addressable detectors warn the panel when they are getting dirty, from dust, building work, cooking fumes or insects. Left alone, a dirty detector is a common cause of false alarms. The fix is to clean or replace the head, and if it keeps happening, to look at whether that detector is the right type for the room.

Sounder circuit fault

A sounder has been removed or damaged, or the end-of-line device on the sounder circuit is missing. Until it is fixed, part of the building may not hear the alarm, so treat it as a priority.

Disablement showing

A zone or device has been disabled, usually to stop a false alarm, and never re-enabled. The panel shows it as a fault or a separate disablement light so it is not forgotten. Find out why it was disabled, deal with the cause, and re-enable it. If the cause was a recurring false alarm, that needs investigating rather than leaving the area unprotected.

When to call an engineer

Call the same day for a mains fail, a sounder fault, an open or short circuit, or any fault in a building where people sleep, such as a block of flats, an HMO, a care home or a hotel. Other faults should still be looked at within a few days. Anything that clears and comes back is worth reporting too, because intermittent faults are usually the start of a bigger one.

We repair any make of fire alarm panel across London, including systems installed by other companies. Call 020 8946 5567 or use the form on this page, and tell us the exact message on the display: it helps the engineer bring the right parts. If your system is due for its service, the fault can be fixed on the same visit.