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In short
A hardwired alarm has two power sources, so a reset means removing both. Kidde and First Alert say: turn off the breaker, take the alarm down and disconnect it, remove the backup battery, and hold Test for 15 to 20 seconds. Then reconnect, put the battery back and restore power. If it still chirps, Kidde points to a loose neutral wire or power surges.
Replacement alarms and batteries:
Kidde 20SD10 (10-year battery) Kidde 20SA10 (hardwired) Energizer MAX 9VReset steps
- Turn off power to the alarm at the circuit breaker.
- Remove the alarm from its bracket and disconnect the wiring plug, if your model allows.
- Remove the backup battery.
- Press and hold Test for at least 15 seconds (Kidde) or 15 to 20 seconds (First Alert).
- Reconnect the plug, put in the backup battery and remount the alarm.
- Turn the breaker back on. Kidde says the unit will chirp once when power is restored and shouldn't chirp after that.
- Press Test to confirm it works.
If it still chirps
- Find the right alarm. First Alert says one unit with a problem can affect an interconnected system. Listen for the one starting the chirp and reset that one first.
- Loose neutral wire. Kidde says a loose white neutral wire can cause an echoing chirp from one unit to the next.
- Power surges. Kidde says chirping at the same time each day may come from a surge when the utility switches grids. If it chirps when something like an exhaust fan or heater turns on, Kidde says to move that device to an outlet on a different circuit or have an electrician look.
- 10-year backup battery. Some hardwired alarms, like Kidde's 20SA10, use a 10-year backup battery. Kidde says sealed-battery models chirp every 30 seconds at end of life, and that means replacing the alarm.
Wiring work is for electricians. NFPA says only qualified electricians should install hardwired smoke alarms. If the wiring at the box looks loose or damaged, call one.
How we work: reset and wiring checks come from Kidde and First Alert. The electrician guidance comes from NFPA. Sources are listed below.
Questions people ask
How do I reset a hardwired smoke detector?
Kidde and First Alert: turn off the breaker, take the alarm down and unplug it, remove the backup battery, hold Test for 15 to 20 seconds, then reconnect and restore power.
Why does a hardwired alarm chirp with no battery?
Kidde says a loose white neutral wire can cause an echoing chirp. Power surges can also make units chirp when power returns.
Can I replace a hardwired smoke detector myself?
NFPA says only qualified electricians should install hardwired smoke alarms.
Sources
Last checked Oct 23, 2026. If an alarm may be real, get out first. Only qualified electricians should install hardwired smoke alarms, NFPA says. Turn off the breaker before taking down a hardwired unit.
