My landlord has recently reinstalled my smoke alarm. It is labelled on the smoke alarm as an "Optical" type.

The smoke alarm appears to be working - it's powered by both mains electricity and battery - it shows a green status light, and when I push the test button it does indeed beep as expected.

However, being a cautious type, I've tried holding a lighting match 20cm or so below it, then extinguishing it. That generates a small puff of smoke. This doesn't seem to trigger the alarm.

Should I reasonably expect that to trigger the alarm? Is there anything else I can do (safely!) to test the alarm?

In case it's relevant, I'm in the UK.

  • It appears I may have found a way; deliberating burning some bread in a grill pan then holding that under the detectors. Whilst keeping a close eye on it, that seems to allow generating lots of smoke without fire. This did eventually cause the detector to go off. I'm curious if the lowered sensitivity from what I'm used to is due to the optical nature. Dec 23, 2013 at 11:52
  • 1
    That's the strength of photocell based detectors (as opposed to the other (ionization based) type of detector). Since it takes a sufficient density of visible smoke particles to set them off, they are less prone to false alarms in places like kitchens where you may generate small amounts of smoke. (and since they are more sensitive to visible smoke, they may detect some types of fire earlier). Ideally you'd have both types of detectors (or dual-sensor) in your home since ionization detectors may detect some fires earlier.
    – Johnny
    Dec 23, 2013 at 20:25

1 Answer 1


There is a chance that burning something may contaminate the sensors. Several companies make an optical alarm test spray. It is an aerosol can that generally costs less than $10 U.S. It is large enough to last several years worth of monthly tests. It should be available at your local home center or hardware store.

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