How often should you test smoke and CO detectors?

Why it matters

Detectors fail quietly — the only way to know one still works is to test it. Working smoke alarms cut the risk of dying in a home fire roughly in half.

How to do it

Press and hold the test button on each unit until the alarm sounds. Replace any unit that fails, and replace every detector older than ten years — the sensor degrades even if the beep still works.

Signs you've waited too long

There is no visible sign of a dead detector. That is the point of testing.

Same part of the house