What is this?
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.
Common causes
- 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 to 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 an electrician 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
Typical cost
£60 – £200
Replacing a single detector head is inexpensive. Relocating a detector or changing its type may require additional wiring work.
