Monthly testing, annual batteries, 10-year replacement
NFPA recommends a three-tier maintenance schedule. Monthly: press the test button on every alarm. If the alarm does not sound, replace the battery immediately. Annually: replace the batteries in every alarm that uses replaceable batteries, regardless of whether it has chirped. Every 10 years: replace the entire unit. Check the manufacturing date printed on the back of the alarm.
Waiting for the low-battery chirp before replacing batteries is risky. The chirp activates when voltage drops below a threshold, but there is no guarantee the alarm will function reliably in the window between "battery weakening" and "chirp activating."
Where alarms go and why
NFPA requires smoke alarms inside every bedroom, outside each sleeping area, and on every level of the home, including the basement. Mount on the ceiling or high on the wall (smoke rises). Keep alarms at least 10 feet from cooking appliances to reduce nuisance alarms.
Interconnected alarms (wired or wireless) are significantly safer than standalone units. When one sounds, all sound, alerting occupants throughout the house even if the fire starts in a remote area.
Ionization vs photoelectric
Ionization alarms respond faster to fast-flaming fires (paper, grease). Photoelectric alarms respond faster to slow-smoldering fires (electrical, upholstery). NFPA recommends using both types or dual-sensor alarms for the best protection, since you cannot predict which type of fire will occur.
- Monthly: press the test button on every alarm
- Annually: replace batteries in all alarms with replaceable batteries
- Every 10 years: replace the entire unit (check the date on the back)
- Install inside every bedroom, outside sleeping areas, on every level
- Use both ionization and photoelectric types, or dual-sensor alarms
- Smoke Alarm Safety — NFPA smoke alarm placement, testing, and maintenance.
- Smoke Alarm Information — CPSC consumer guidance.