The right way to check your smoke alarm

John Conlin / 25 January 2017

Are you checking your smoke alarm correctly? Our chartered surveyor explains.


I have been told that just because a smoke alarm sounds when the test button is pressed does not necessarily mean that it is working.

Is this correct, and if so how can one check that the alarm is really working?

What is Nest?


What you have been told is correct but largely unknown.

The detector unit within an alarm contains a very small amount of radio active material that becomes less sensitive as it ages over time. Pressing the test button or seeing a flashing light merely indicates that the battery or mains supply is working.

Aerosol cans of synthetic smoke are readily available and are a positive test for smoke alarms.

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The material is for general information only and does not constitute investment, tax, legal, medical or other form of advice. You should not rely on this information to make (or refrain from making) any decisions. Always obtain independent, professional advice for your own particular situation.