How to safely disconnect a Firex smoke detector from its power source
Unplugging a Firex smoke detector means cutting power to the unit so you can remove it, replace the battery, or take it down for cleaning or replacement. The method depends on whether your Firex is hardwired to your home's electrical system, battery-powered, or both. Most Firex models sold for home use are either battery-only or have a backup battery alongside hardwired power. Before you start, turn off the breaker that controls that circuit if the unit is hardwired, then physically disconnect the detector from its mounting bracket.
The entire process takes about ten minutes for a hardwired unit and two minutes for a battery-only model. You will need a breaker switch (already in your electrical panel), a lamp or outlet tester to confirm power is off, and possibly a screwdriver if your model uses screws instead of a twist-lock. Keep the mounting bracket in place unless you are removing the detector permanently — reinstalling becomes much easier if the bracket stays mounted and ready.
Key Takeaways
- Turn off the breaker controlling the smoke detector's circuit before touching any hardwired connections.
- Most Firex detectors twist or slide off their mounting bracket, and the power connector unplugs from the back or bottom of the unit.
- Battery-only Firex models require no breaker switch — straightforward remove the detector from the bracket and slide out the battery.
- After unplugging, test the breaker with a lamp or outlet to confirm power is truly off before handling any wires.
- Keep the mounting bracket in place if you plan to reinstall the same detector later.
Identify your Firex model and power type
Check the back or bottom of your Firex detector for a label showing the model number. Firex makes several common models: the 4618, 2000, i4618, and i5000 are among the most widely installed. Look for text that says "hardwired" or "AC powered" if the unit is connected to your home's electrical system. If you see only "battery operated" or "battery powered," the detector runs on batteries alone and requires no breaker switch.
If you are unsure, look at the mounting bracket on your ceiling or wall. A hardwired detector will have a wire bundle coming out of the bracket into the wall or ceiling. A battery-only detector will have no wires — just the bracket itself. Many newer Firex models are hardwired with a battery backup, meaning they draw power from your home's circuit but also contain a replaceable battery for emergencies. The label will tell you which type you have, so take a moment to read it before proceeding.
Turn off power at the breaker for hardwired units
Locate your home's electrical panel and find the breaker labeled for smoke detectors, hallway, or the room where the detector is mounted. If the breaker is not labeled, you may need to flip breakers one at a time and have someone watch the detector to see when it stops working. Once you find the correct breaker, switch it to the OFF position.
Test that power is truly off by using a lamp, phone charger, or outlet tester in the same room. Plug the device into a nearby outlet — if it does not work, the breaker is off. Do not skip this step. Even though smoke detectors run on low voltage, touching live wires can cause injury. After confirming the power is off, you can safely proceed to remove the detector from the wall or ceiling.
Remove the detector from its mounting bracket
Most Firex detectors are held to the bracket by a twist-lock or slide mechanism. Look at the edge of the detector where it meets the bracket. If you see a slot or arrow, the detector slides out in that direction — usually straight down or to one side. If there are no visible slots, the detector twists counterclockwise. Grip the detector firmly and turn or slide it gently until it separates from the bracket.
Do not yank or force the detector. If it does not move after gentle pressure, check the bracket again for a release tab or button. Some Firex models have a small plastic tab on the side that must be pressed while you twist. Once the detector comes free, set it on a clean surface where you can work without dropping it. The bracket itself should remain mounted to the ceiling or wall unless you are removing the detector permanently.
Unplug the power connector from the detector
Look at the back or bottom of the Firex detector for a white or black plastic connector. This connector plugs into the detector and carries power from the wires in your ceiling or wall. Grip the connector itself — not the wires — and pull straight out. The connector should come free with gentle, steady pressure. If it does not budge, wiggle it slightly side to side as you pull, but do not twist or bend the wires.
For battery-only Firex models, there is no connector to unplug. straightforward remove the detector from the bracket and locate the battery compartment on the back or side. Slide or press the battery release tab and remove the old battery. If you are replacing the detector entirely, you can now discard it or set it aside. Keep the connector clean and accessible in case you install a new detector in the same location later.
Remove the battery if you plan to store the detector
If your Firex has a backup battery and you are unplugging it for storage or replacement, remove the battery as well. Open the battery compartment — usually a small door or sliding panel on the back of the unit. Most Firex detectors use a 9-volt battery. Slide the battery out of its holder and set it aside. If the battery is old or dead, replace it with a fresh 9-volt battery before storing the detector, so it will work if you reinstall it later.
Do not leave a dead battery in a detector you plan to keep. Dead batteries can corrode inside the compartment and damage the detector's circuitry. If you are discarding the detector, remove the battery and recycle it separately according to your local hazardous waste guidelines. Many retailers that sell batteries, such as Best Buy or Home Depot, accept old batteries for recycling at no charge.
Turn the breaker back on and test the circuit
Once the detector is fully unplugged and removed, switch the breaker back to the ON position. Test the circuit by plugging a lamp or outlet tester into a nearby outlet to confirm power has returned. If you are installing a new Firex detector in the same location, follow the manufacturer's instructions to connect the new unit to the same power connector and bracket.
If you are leaving the bracket empty, you may want to cap the power connector with electrical tape or a wire nut to prevent accidental contact. Do not leave bare wires exposed in your ceiling or wall. If you removed the detector for cleaning or battery replacement and plan to reinstall it, may support the battery is fresh and the connector is clean before plugging it back in. A quick visual check of the connector for dust or corrosion takes only a moment and can prevent connection problems later.
Frequently Asked Questions
Do I have to turn off the breaker to unplug a Firex detector?
Yes, if your Firex is hardwired to your home's electrical system. Turning off the breaker removes power from the circuit and makes it safe to handle the connector and wires. Battery-only Firex detectors have no breaker to turn off — you can remove them directly from the bracket.
What if I cannot find the correct breaker?
Flip breakers one at a time and have someone watch the detector or a light in that room. When the detector stops working or the light goes out, you have found the right breaker. Mark it with tape so you know which one controls the smoke detector circuit. If the detector has a battery backup, it may still show a light or beep even after the breaker is off.
Can I unplug a Firex detector while the breaker is still on?
It is not safe. Even low-voltage connections can cause injury or damage if you touch live wires. Always turn off the breaker first, then test the circuit with a lamp or tester to confirm power is off before unplugging anything.
What should I do with the power connector after I remove the detector?
If you are not reinstalling a detector in that location, cap the connector with electrical tape or a wire nut to prevent accidental contact with bare wires. If you plan to install a new detector later, leave the connector accessible and clean so you can plug the new unit in easily.
Do I need to replace the battery after unplugging the detector?
Only if you plan to reinstall the detector later. A fresh battery ensures the backup power will work if the hardwired circuit fails. If you are discarding the detector, remove the old battery and recycle it separately.