Smoke and CO alarms
Smoke alarms go in each bedroom, outside each sleeping area and on every level. CO (carbon monoxide) alarms go outside each sleeping area and on every level.
Find the right fit
- Model number. Start with the old alarm: its back label shows the model, the kind (smoke, CO or combination) and the date it was made. If your alarms are interconnected (linked so they all sound together), a new one needs to work with that setup.
- Part number. Then the power: the battery type printed inside the cover, or a sealed 10-year battery.
- Two or more retailers. Look the model or part number up at two or more retailers. Buy the one listed as a fit for your model, and check the printed size or part number on the box matches.
What to look for
- A safety listing mark on the package, which means the alarm was tested to a safety standard.
- Interconnected alarms sound together, so an alarm on one level wakes people on another.
- A test button you can reach.
- Write the install date on the back.
Source: smoke alarms (U.S. Fire Administration (FEMA), Smoke Alarms, opens in new tab) · CO alarms (U.S. Fire Administration (FEMA), Carbon Monoxide Poisoning Prevention, opens in new tab)
General guidance only. Check your local codes and authorities, which can be stricter than national rules.
When to swap
Test monthly. Replace smoke alarms 10 years after the date on the back; CO alarms by the date printed on yours.
Where to buy
Set a reminder for the next one in the Reminder Tool or the home hunt.