How often should you test smoke and carbon monoxide alarms?

An alarm on the ceiling looks the same whether it works or not. The monthly test and the yearly battery change are what make sure it sounds when it has to.

Every month: press the test button

Hold the button until the alarm sounds. If it's weak or silent, change the battery and test again, and replace the alarm if it still doesn't sound. Connected alarms should all go off when you test one.

Every year: the batteries

Alarms with replaceable batteries need a new battery at least once a year, and many people do it when the clocks change. Alarms with a sealed 10-year battery skip this, but still need the monthly test. A chirp usually means the battery is low.

Every 10 years: the alarm itself

Smoke alarm sensors wear out, so NFPA says to replace smoke alarms at least every 10 years. The date of manufacture is printed on the back. Carbon monoxide alarms last somewhere between 5 and 10 years depending on the model, so replace them when the end-of-life signal sounds or the date in the manual arrives.

Where they go

• Smoke alarms: inside each bedroom, outside each sleeping area, and on every level of the home.
• CO alarms: outside each sleeping area and on every level, in any home with gas appliances, a fireplace or an attached garage.

Common questions

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