Updated
Fire Alarm Keeps Going Off
Your mains-wired fire alarm keeps triggering when there is no fire or smoke.
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What's happening?
A fire alarm that keeps going off without a genuine fire is known as a false or unwanted alarm. While extremely annoying (especially at night), it is important not to disable the alarm entirely. False alarms from mains-wired systems are common and usually have an identifiable cause.
What usually causes it?
- Smoke alarm fitted in or too close to the kitchen picking up cooking fumes
- Steam from a bathroom triggering a nearby smoke alarm
- Dust or insect contamination inside the detector
- Detector at end of life becoming oversensitive
- Incorrect detector type for the location (ionisation type near a kitchen)
- Electrical interference on the alarm circuit
Is it dangerous?
False alarms are not directly dangerous but they create a serious indirect risk: alarm fatigue. If you disconnect or ignore the alarm because of frequent false alarms, you remove your early warning system for a real fire. Fix the cause rather than disabling the alarm.
Can I fix it myself?
Identify which alarm is triggering first — it usually has a different LED indicator or sounds slightly before the others. If it is near the kitchen, cooking fumes are the likely cause. Clean the detector by gently vacuuming the vents. If the alarm is more than 8-10 years old, it may need replacing.
When should you call an electrician?
Call an electrician if you cannot identify which alarm is causing the false alarms, if the alarm is triggering at random times with no apparent cause, if you need to relocate an alarm that is too close to a kitchen or bathroom, or if the detector needs replacing with a more suitable type.
What will the electrician actually do?
- Identify the triggering detector using the alarm panel or visual indicators
- Test and clean the detector
- Replace with an appropriate detector type for the location
- Relocate detectors that are too close to kitchens or bathrooms
- Test the complete system after any changes
What will it cost to fix?
£60–£200
Replacing a single detector head is inexpensive. Relocating a detector or changing its type may require additional wiring work.
Find an electricianFrequently asked questions
We’re happy to answer all your questions.
Why does my fire alarm keep going off when I cook?
You likely have a smoke alarm too close to the kitchen, or it is an ionisation type which is very sensitive to cooking fumes. A heat alarm should be used in kitchens, with smoke alarms positioned in the hallway outside.
What is the difference between ionisation and optical alarms?
Ionisation alarms are very sensitive to small smoke particles from fast-burning fires but also to cooking fumes. Optical alarms are better at detecting slow-smouldering fires and are less prone to cooking false alarms. Optical alarms are now recommended for most domestic locations.
Can I just remove the battery to stop the false alarm?
On mains-wired alarms, removing the battery does not stop them — they run on mains power. Removing the detector from its base will stop it, but you should not leave it disconnected. Get the issue fixed instead.
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