The LWF Blog

Facilities and Fire Alarm Systems – Dealing with False Alarms Pt 2

May 1, 2014 11:13 am

Part two of this series on false fire alarms continues to look at potential reasons why your business might be experiencing regular false alarms, causing building evacuation and other time consuming and costly procedures to be instigated, without any obvious cause.

Very often, the alarm system itself gets the blame when, in actual fact, technical issues are very rarely the cause of false alarms. This series might have been called ‘100 reasons why it isn’t your fire alarm system at fault’, but in any case, there will be a firm and tangible reason why you are experiencing false fire alarms and these blogs will help you find what it is.

A fire alarm system will have been designed specifically for your building, at the time of installation. This point is perhaps key; the system was designed for the usage at that time and it’s entirely possible that things may have changed.

Changes of use

While it may be obvious to most people that a change of use of an entire building would require a full review of the fire safety and prevention provision within the building, there are often changes within the same business that can cause serious issues to the fire alarm system.

These changes can be as simple as a new maintenance man smoking a pipe on his break outside a room which has smoke detectors and the smoke drifting back inside, or an illicit toaster which has been brought in by a member of staff for a hot morning snack. 

More commonly it is found that changes come about when outside contractors are brought in to undertake work. Plumbers, electricians or a building contractor using a blow-torch are all able to cause heat and smoke that was not anticipated within the room at the time of fire alarm system design.

As it is the fire alarm system’s job to recognise potential sources of fire and smoke and to alert you, it cannot be said that this is a problem with the fire alarm system.


Temporary changes of use of a part of a building, through contractor use, can be taken into account by temporarily isolating a part of the fire alarm system, to avoid false fire alarms, while work is undertaken. However, on a long-term basis, the isolation of any part of the system could be potentially dangerous and if the change of use is long term or permanent, a fire alarm system re-design should be commissioned to ensure the safety of the building’s occupants.

Environmental Changes

Changes to the environment within a room which do not have additional smoke or flame can still affect the fire alarm system causing false alarms. Consideration should be given to changes within a room such as it being open to the outside elements, through a window or a hole. Excessive dust in the air in a room, such as caused by building contractors, can cause issues to the detection system.

The detectors within the room will have been designed to work in a particular environment and any change to that environment can cause unwanted alarms. When changes are made, consideration must be given to the type of detector within the room to avoid issues down the line.

If issues are experienced after changes have been made to the environment, it may be that repairs or amendments can be made to the environment of the room could solve the problem, or it may be that the fire alarm system itself will require adapting to the new environment.


Malicious Operation


Rarely, but worryingly, malicious operation of fire alarm systems can occur. On an occasional basis, it may be that the ‘break glass’ points are triggered, but also it has been known for people to initiate a fire alarm by holding a lighter or match directly under a fire detector.

If this is a problem and could potentially be caused by visitors from outside the staff of the business, it is essential that access to the building is limited. Visitors should not be left alone in any areas of the building.

If the concern is that a member of staff or regular building user may be responsible, it may be possible to isolate the perpetrator by looking at work schedules and access to that area. If footfall in an area is too high to do this, simply moving the call point or detector may be a solution, if it is considered safe to do so. Additionally, a security camera pointed at the area of concern can be both a deterrent and an effective way of pinpointing who is to blame. 


Next week’s blog will continue to look at the issues caused by false fire alarms and the potential causes. In the meantime, if your business is being disrupted by false fire alarms and you have not been able to isolate the cause, please contact Peter Gyere on 020 8668 8663. LWF have been working with their clients for over 25 years to promote and provide fire safe design and planning.

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