Reduce your chance of fire

Unwanted activations can be disruptive and become a nuisance if not dealt with in the correct way. Always log any unwanted activation in the systems log book and take any remedial action that is required.

The following guidance provides examples and information that may help improve the reliability of a fire alarm system and can be the first steps to reducing false alarms combined with regular maintenance inspections. Common causes of unwanted fire signals are:

• Cooking fumes
• Steam
• Aerosol sprays
• Smoke
• Dust Contamination
• Insects
• Water ingress
• External fumes
• Environmental conditions
• Technical faults
• Mechanical damage


Common causes of unwanted fire signals are:

Cooking fumes

Cooking fumes cause the majority of unwanted activations especially in Houses of Multiple Occupancy.

The kitchen area will usually be protected by a heat detector that will not be affected by fumes from cooking, however these fumes can easily filter into an adjacent area activating a smoke detector especially if the kitchen door is held open and leads onto a small lobby.

Do not prop open kitchen doors and always use appropriate extraction where possible.


Steam can activate optical smoke detectors. If the bathroom door opens onto an area that is covered by one of these detectors avoid propping the door open and use the extractor fan (if fitted).

Aerosol Sprays

Aerosol sprays can also activate smoke detectors when used close to or excessively. Always use aerosols with care and direct the spray away from smoke detectors.


Smoking, Candles & Incense all produce smoke in a controlled way and if the smoke is directed towards a smoke detector or excessive smoke is created this may also activate the alarms. Avoid creating controlled smoke in close proximity of smoke detectors.

Vaping & E-cigarettes also create a mist/vapour "cloud" that may cause a smoke detector to activate if directed towards the detector.

Dust contamination

The ingress of dust can cause a change in the sensitivity of a smoke detector and a large build up will likely result in the activation of the unit. Some new detectors compensate for a gradual build-up of dust over a period of time however all are likely to be contaminated by a sudden large influx often caused by decorating or building works.

Regular cleaning regimes will keep dust levels down in any area and try to protect detectors from contamination by temporarily covering them if works are being carried out in an area. Always ensure that if you leave an area you remove any protection you have put around the detectors and return the fire cover to normal.

Note: Just isolating the zone from the control panel at the time of the works will stop the detectors activating during the works however the devices may still become contaminated and play havoc at a later date. 


 Small insects can make nests in smoke detectors causing a change it the sensitivity much like dust. Regular cleaning regimes in the area can help prevent this.

Water ingress

Water damage from leaks will more often than not activate a detector, this will usually result in the affected unit having to be removed and linked out. The leak will need to be repaired and the area dried before installing a new unit.

External fumes

Smoke from bonfires or any external fire can enter a property through open windows and cause a smoke detector to activate especially on hotter days when more windows are left open. Simply closing the window to stop any smoke entering the property will solve this problem.

Environmental conditions

Weather conditions such as electrical storms can cause malfunctions on fire alarm systems. If this happens always log the event inform your maintenance company and get the alarms checked for any permanent damage.

Technical faults

As with all/any electrical equipment, occasionally there are malfunctions and breakdowns. Log the event, inform your maintenance company and take any remedial action that is required.

Mechanical damage

Accidental damage can occur whilst works are being carried out on a property and on the odd occasion malicious damage is caused. Log the event and arrange for your maintenance company to carry out any remedial works required.

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Brighton Fire Alarms provide us with an excellent service. They are reliable, trustworthy and provide a high standard of work. We thoroughly recommend them.

Jemima Hall, Office Manager, Harper Stone Properties Ltd