Reduction of false alarms
We have seen a rapid growth of installed
automatic fire detection (AFD) systems due to their success
in providing an early warning in the event of a fire, saving
lives and limiting property damage.
While the fire service is dealing with a false alarm they are
not available to tackle real fires, they waste essential
resources (putting lives at risk) and they disrupt other activities
such as training and community fire safety work.
However, the problem is not exclusive to the fire
service as false calls also erode your confidence in the
value and reliability of your AFD systems and can cause costly
interruptions to manufacturing work procedures.
What is an “unwanted fire signal”?
Any fire alarm or fire signal other than a genuine fire or test
What can cause the “unwanted fire signal”?
An “unwanted fire signal” can be caused by a variety of reasons,
most of which can be eliminated by careful planning. Typical
sources of false alarms are:
- activation of a smoke detector by airborne pollutants
- vandalism/malicious action
- human error (generally due to unfamiliarity with the
- faulty or non-maintained equipment
What can you do to reduce the “unwanted fire signals”?
If there is definitely no fire:
- silence the fire alarm but do not reset the control panel as
this will cancel the indications required for investigation
- check the indications on the control panel and establish the
area (zone) of the building where the fire alarm originated from.
Your system may also indicate the precise location of the actuated
- as soon as possible after the unwanted alarm occurred, visit
the area and locate the break glass call point, heat or smoke
detector that has been actuated
- attempt to establish the reason why the call point or detector
was actuated. It is also useful to talk to people who were in the
vicinity of the actuated device when the alarm occurred. Ask them
if they know what happened and why. However it may be necessary to
investigate further to determine the real cause e.g. vandalism or
accidental damage to a break glass call point or insects entering a
- if the actuated detector cannot be readily located, it may be
that it is fitted in a duct or above a false ceiling. Check to
establish if the detector location drawings are available and if
so, use these to help locate the detector. Break glass call points
should be easier to locate as they should be mounted in clearly
- if the control panel does not indicate the location of the fire
alarm or if there is no actuated detector, call in the maintenance
company as the problem may be due to an equipment fault
- the occupier should accurately record all the information
relating to the fire alarm incident in the system log book
irrespective of whether it was a genuine or unwanted alarm. This is
very important as the information may be needed at a future
- if unwanted alarms continue and the cause is not evident or
remedial actions are unsuccessful, then it is useful to analyse the
times at which unwanted alarms occur and the locations from which
they originate. This will help to establish if there is any pattern
that may help to identify the cause e.g. cooking prior to meal
times or a boiler switching on early in the morning.
The investigations and the analysis should lead to a conclusion
that the unwanted alarms are the result of one or more of the
- human error - it is likely that the problem
can be overcome by a change of existing practices e.g. the issuing
of 'permits to work' or the training of building occupiers Examples
of this type of problems are:
- smoke caused by building contractors undertaking 'hot work'
close to smoke or heat detectors
- alterations to the fire alarm system wiring without isolating
- process induced alarms - many unwanted alarms
result from processes undertaken adjacent to fire detectors,
particularly smoke detectors. A well known example being the result
of burning toast in a toaster. Such unwanted alarms can be remedied
by either changing the location of the offending process, changing
the detector type or its location or by changing the way the fire
alarm system is configured
- equipment faults. If there are equipment
faults, these will need to be discussed with the fire alarm system
maintainer and appropriate action taken to remedy them. Effective,
regular maintenance, which includes the internal and external
cleaning of smoke detectors, will minimise such faults occurring in
the first instance
- malicious actuation This cause can be the most
difficult to determine and often requires careful analysis of the
occurrences. Examples include:
- the malicious operation of break glass call points
- the illicit ownership and use of callpoint test keys e.g. by
- the intentional directing of smoke, e.g. from a cigarette into
a smoke detector
- actuation of an unsecured control panel usually as a result of
the control enable key being left in the panel.
You should consider all these factors in relation to your
building and develop a plan to avoid unwanted alarms.