BRK CO5120BNA Carbon Monoxide Alarm, 120V Hardwired w/ Battery Backup

Compatibility Check: Will it fit your existing bracket?

One of the biggest headaches for DIYers is buying a new alarm only to find the screw holes don't match.

The BRK CO5120BNA features a Universal Mounting Bracket with large keyhole slots. It is designed to fit most standard electrical boxes without you having to remove the existing screws. If you are replacing an older BRK or First Alert hardwired unit, this model is often a direct "plug-and-play" replacement, sliding right onto the existing mount.

Step-by-Step DIY Installation

You don’t need specialty tools or an electrician for this upgrade. Follow these simple steps to secure your home in under 15 minutes:

1. Power Down: Turn off the power at your home's breaker panel for the alarm circuit.
2. Remove Old Unit: Twist your old alarm counter-clockwise and unplug the wiring harness.
3. Check the Bracket: If you’re replacing an older BRK model, the bracket might already be a match. If not, swap it out using a standard screwdriver—the keyhole slots make this effortless.
4. Quick-Connect: Plug the new "Quick-Connect" wiring harness into the back of your CO5120BNA.
5. Mount & Locked: Twist the unit onto the bracket. Use the optional locking pin if you want to prevent tampering.
6. Activate & Test: Slide the 9V battery into the side-load compartment (no need to take the unit down!) and press the Test/Silence button. Once you hear the 85dB beep, you’re protected.

Frequently Asked Questions

Is this compliant with Ontario Fire Code?

Yes. Ontario law requires CO alarms outside all sleeping areas and in service rooms. The CO5120BNA meets and exceeds CAN/ULC S531 standards required in the province.

What is the "Latching Alarm Indicator"?

If you have multiple alarms interconnected and one goes off while you're out, the "Latching" feature flashes the LED on the unit that first detected the gas. You’ll know exactly where the leak started.

How often do I need to change the battery?

The 9V backup battery should be replaced once a year. Thanks to the Side-Load Battery Drawer, you can swap it in seconds without ever removing the alarm from your ceiling.

Does it detect smoke too?

No, this is a dedicated Carbon Monoxide alarm. For full protection, we recommend pairing it with a BRK Hardwired Smoke Alarm in an interconnected system.