Safety First: When replacing smoke detector batteries, turning off the power at the electrical panel is important to prevent electric shock.
In short yes. Hard-wired smoke detectors run directly from a circuit panel should be powered down to change. If they are run in series with other smoke detectors, all should be changed at the same for compatibility. No fun grounding out on live wires.
Turn off the circuit breaker for your smoke alarms. If your smoke alarms don't have battery backup, doing that will turn all of them off. If your smoke alarms have battery backup, go to the faulty smoke alarm, twist off the cover. Once the wires are exposed, carefully disconnect the smoke alarm.
Edit: From experience with similar units releasing the battery does not require disconnecting mains wiring. When you release the base there should be enough slack to let you lift the battery cover lid and take the battery out. If you are unsure just turn the fuse board off completely before you do it.
Disconnect each smoke alarm.
Repeat this for every unit. Many user manuals instruct you to first shut off the power before attempting to disconnect the plug powering a unit. This may help avoid the risk of shock if there is a problem with the connector or the high-voltage wiring.
Several common causes can explain why your hard-wired smoke detector is beeping: Low battery: Even hard-wired smoke alarms have backup batteries that need replacing periodically. A low battery can cause that annoying beeping sound. Dust buildup: Dust and debris inside the smoke detector can trigger false alarms.
Test smoke alarms every month by pressing their test buttons. If your alarms use regular batteries, swap in fresh batteries at least once a year. A “chirping” sound means that it's time to change batteries. Because alarm sensors wear out, replace each alarm at least every 10 years.
Can I install a hardwired smoke detector myself? While it is technically possible, it is not recommended. Working with your home's electrical system can be dangerous and complex, best left to a qualified electrician.
Tip: Before working on a hard-wired smoke detector, turn off the main power at your circuit breaker to avoid electrical shock.
It is recommended you test your alarms at least once a month to ensure they are working properly, and replace the batteries in your smoke alarm every six months. The detector itself should be replaced at least every ten years.
Pressing the “Test/Silence” button on the front of the unit should stop it from beeping or chirping. If this doesn't work, grasp the device and turn it counterclockwise. It should detach from the base so you can open the battery compartment in the back. Remove and replace the battery to see if it caused the issue.
This chirping happens every 30 to 60 seconds for at least seven days. When you hear this, it means the battery needs replacing.
Hardwired smoke detectors can still beep even if there is no battery. Possibly the backup battery might have been activated and that can signal a problem. The backup battery may have run out and that is causing your hardwired smoke detector to chirp.
Disconnect power source
So, disconnect it from the main power supply before handling any of your devices to avoid electric shocks or damage to your safety units. Hardwired components have backup batteries installed to ensure the efficient flow of power even during power outages.
Clear Residual Charge to Stop the Chirp
Remove the alarm from your ceiling or wall. Open the cover and take out the battery. Press and hold the test button for 15-30 seconds. This will fully reset the smoke alarm and drain any charge left inside.
Perhaps you have a hardwired smoke alarm that is connected to your electrical breaker. If this is the case, you'll need to make your way to the electrical panel and look for a breaker labeled “Smoke Alarms” or “Central Smoke Alarm.” Turn the breaker to the off position and wait a few minutes before turning it back on.
A: Remove the alarm from the mounting plate by rotating it counterclockwise (as indicated by the arrows on the cover of the alarm). Next, on the back side of the alarm, locate the area marked with a long arrow on the product label. Break through the label with a screw driver and turn the screw to the “OFF” position.