When to Replace a Smoke Detector

A person testing the battery on a smoke detector.
  • 1 hours
  • Beginner
  • 15
What You'll Need
Vacuum or can of compressed air
Electric meter

Smoke detectors are fairly inexpensive, but important, devices that warn you of fire in your home. The need to replace one may not present a financial burden, but there are certain tests to make before you actually throw it away and replace it with a new smoke alarm. You need to perform a series of tests to know when to replace a smoke detector.

Test the Detector

First, press the test button to check the battery power. The battery should be replaced once a year. Pick a certain date that can be remembered, like when switching to or from Daylight Savings time, to replace all smoke alarm batteries.

If the battery is good, place a lighted candle 6 inches below the detector, allowing the candle to heat the air rising to the unit. If no alarm sounds within 15 seconds, blow the candle out and let the smoke rise to the detector. If the alarm still doesn’t sound, remove the cover and clean out the interior using either a vacuum or can of compressed air.

Check all electrical connections to make sure they are secure. If after this test the unit still does not work, replace it.

Alarm Scenarios

You will need to replace the unit if you hear no sound when smoke is present, even if the battery is still good. Replacing either a sensor or a sounding device isn't financially prudent.

If the detector sounds an alarm and no smoke is present make sure the alarm is more than 20 feet away from your stove and oven, for example, in a hallway off of a kitchen. If not, relocate it and check to see if it continues to go off. Try replacing the battery first, though. If it continues to sound with a good battery and no smoke present, you more than likely have a bad sensor and you need to replace the unit. If it is near a furnace, bathroom, or utility room, you also should relocate it at least 10 feet away. If these suggestions do not work, you need to replace the unit.

Voltage Check

If you have a built-in smoke detector alarm system wired into the house and one unit in one room does not work, remove the cover to the wiring connections. You need to check the voltage coming into the unit from the house wiring by placing the red wire from the meter to the terminal screw for the red wire coming from the house power source. If you get a reading, then you have power to the unit and the unit may be faulty.

If you see any signs of melted wires or singed insulation, you more than likely either have a bad unit or faulty wiring. At this point, you should call an electrical professional for help. Always be careful working around live wires.

Now that your smoke detectors are tested and working, how about going through a fire drill with your family?