The LWF Blog

Facilities Management – Fire Alarm Systems and False Alarms – Part 18

October 6, 2016 3:02 pm

In this recent blog series for those people who work in Facilities Management and have an interest in or responsibility for fire safety, we have been looking at fire alarm systems. In part 17 of the series we began looking at false alarms and how they can be avoided, and we will continue in that theme in this edition.


BS 5839:1 (the British Standard that offers guidance and restrictions on the use of fire alarm systems) suggests that if the environment in which the fire alarm is placed has no tendency towards dust, fumes and insects and the system is subject to a good standard of management and maintenance, that false fire alarm rates could be reduced to as low as one false alarm per 100 detectors per annum. On a site with shift working, such as a hospital, this figure can be increased to around one false alarm per 75 detectors per annum and in general use, a rate of one false alarm per 50 detectors per annum is considered normal.


If in any period of 12 months, the level of false alarms rises to one per 20 detectors, BS5839:1 states that a specialist investigation be put into action to ascertain the issue causing such a high level of false alarms in system which have more than 40 detectors. This is also the case if one manual call point or detector is the source of three or more false alarms.


In cases where the alarm system has less than 40 detectors, an investigation should be instigated if there have been three or more false alarms in any 12 month period.


BS5839:1 also lays out the necessity for adequate maintenance of the fire alarm system as a way to help combat the problem of false alarms. This would mean discussing the situation with the maintenance company, so that they are apprised of the issues which have been experienced. For this reason, it is important to keep accurate records of the circumstances of each false alarm triggered, including date, time, which detector/area, signal code etc.


A preliminary investigation, as per BS5839:1, should be instigated as a part of servicing if any of the following conditions apply:


– False alarm instances over the previous 12 months exceeded one false alarm per 25 detectors.


– 11 or more false alarms occurred since the last service.


– Two or more false alarms were triggered by a single manual call point or detector.


– Any persistent cause of false alarms has been identified.


The next blog in the series will continue looking at false alarms, what you can expect and how to approach combatting the problem. In the meantime, if you have any queries about your own facilities or wish to discuss this blog series, please contact Peter Gyere in the first instance on 0208 668 8663.


Lawrence Webster Forrest is a fire engineering consultancy based in Surrey with over 25 years’ experience, which provides a wide range of consultancy services to professionals involved in the design, development and construction and operation of buildings.


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