Smoke alarms need regular testing and replacement once they reach the end of their working life (typically 10 years).
All smoke alarms will expire, there's usually a sticker either on the side or the back which will tell you the expiration date. The electrical supply may continue to work, but age, dust and contamination can affect the alarm’s internal sensor. Newer modern alarms have an app you can use to 'tune in' to the alarm and see the levels of contamination.
How often should you test a smoke alarm?
Ideally test every smoke alarm in your home at least once a month. Press and hold the test button until the alarm sounds. Government fire safety guidance also recommends cleaning alarms with a vacuum every six months to remove dust.
For linked alarms, one test should activate the other connected alarms. You may hear each unit sound in turn, depending on the system. A failed connection can leave part of the house without an effective warning.
Add the test to an existing monthly routine. The first day of each month works well. Test the alarms again after electrical work, cleaning, a battery change or a long period away from home.
Why replace smoke alarms every ten years?
Smoke alarms contain electronic components and sensors that deteriorate with age. Mains power and a working test sound do not confirm that an old sensor will respond to smoke as its manufacturer intended.
Most Aico alarms have a ten-year lifespan and carry a “Replace By” date on the unit. Aico recommends replacing the complete alarm by that date.
Replace an alarm sooner if:
- It fails a button test
- It shows damage, staining or signs of heat
- It gives repeated false alarms after cleaning
- You cannot identify its age
- The manufacturer specifies a shorter service life
Carbon monoxide alarms may have different replacement periods, so check the label and instructions for each unit.
Check the alarm type before buying a replacement
Domestic properties may contain optical smoke alarms, heat alarms or multi-sensor alarms. Each type suits a different location.
A heat alarm usually suits a kitchen because cooking fumes and steam can trigger a smoke alarm. Smoke alarms should sit away from kitchens and bathrooms where steam may cause nuisance alarms or damage.
For mains-powered or interlinked systems, use a compatible replacement. A unit that fits the existing base does not guarantee full compatibility with the other alarms. An electrician can identify the system, confirm the correct alarm type and test the interlink after installation.
Common smoke alarm mistakes
Homeowners often test one alarm and assume the whole system works. Test each unit and confirm that linked alarms sound.
Other common problems include painting over alarms, covering them during decorating and forgetting to uncover them. Dust from building work can also contaminate the sensor.
Never remove an alarm or its battery because it produces nuisance warnings. The alarm may need cleaning, relocation or replacement.
Smoke alarm FAQs
Do mains-powered smoke alarms need replacing after ten years?
Yes. Mains power does not prevent the sensor and internal components from ageing. Check the manufacturer’s replacement date.
Does pressing the test button test the sensor?
The button confirms that the alarm’s electronics and sounder respond to the test function. It does not justify keeping a unit beyond its stated service life.
Can an electrician replace a hard-wired smoke alarm?
Yes. An electrician can isolate the supply, identify a compatible model, fit the alarm and check any interlinked units.
Where can I find the age of my smoke alarm?
Look for a manufacture date or “Replace By” date on the side or back. The alarm may need twisting off its base to reveal the label. Isolate the circuit first where the manufacturer’s instructions require it.
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