How to test smoke and carbon monoxide alarms

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In the video, Brian presses the test button on a ceiling-mounted alarm. It takes seconds, and fire-safety agencies recommend doing it every month.

Video by Brian Huie on YouTube. Watch on YouTube

How often
Test monthly
Video
16 seconds

How often should you test smoke and CO alarms?

Test smoke alarms and carbon monoxide alarms at least once a month. The National Fire Protection Association, the U.S. Fire Administration and the Seattle Fire Department all give the same advice. Test again after changing a battery or after a power outage.

How do you test them?

  1. Press and hold the TEST (or TEST/SILENCE) button until the alarm sounds.
  2. Listen for a loud, clear alarm. A weak sound or no sound means the battery or the alarm needs replacing.
  3. Once a month, lightly vacuum around the vents. Dust can cause false alarms or lower sensitivity.

Where should carbon monoxide alarms go?

Put a CO alarm outside each sleeping area and on every level of the home, mounted at the height the manufacturer specifies. Interconnecting all CO alarms gives the best protection.

When do CO alarms need replacing?

CO alarms wear out. Kidde rates its alarms for 7 or 10 years, and the Seattle Fire Department puts typical life at about seven years. A quick beep every 30 seconds that new batteries do not stop means the alarm has reached the end of its life.

Safety notes

  • If a CO alarm sounds, get everyone outside to fresh air right away, call for help from outside and stay out until responders say it is safe.
  • Run generators outdoors, away from windows, doors and vents, and never run a car in the garage, even with the door open.

Seattle-area notes

Washington requires carbon monoxide alarms in residences. Older owner-occupied homes are exempt until sold; at sale, the seller must install CO alarms before the buyer moves in.

When to call a pro

If a CO alarm keeps chirping after new batteries, call the fire department.

Related guides

How to install a smart smoke detector (with air quality monitor)How to check a fire extinguisherAll Home Care Manual guides

Sources

  1. NFPA smoke alarm tip sheet
  2. U.S. Fire Administration: test CO alarms monthly
  3. Seattle Fire Department: smoke and CO alarms
  4. First Alert: testing smoke and CO alarms
  5. NFPA carbon monoxide tip sheet
  6. CPSC Carbon Monoxide Information Center
  7. Kidde: when to replace alarms
  8. RCW 19.27.530 (Washington CO alarm law)

Checked October 2026. Manufacturer instructions for a specific model come first. General information, not a substitute for a licensed professional.

From the Home Care Manual by Brian Huie, a principal broker with Compass Real Estate in Seattle.