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First Alert

First Alert BRK Carbon Monoxide Detector, Hardwired Alarm with Battery Backup, CO5120BN, White

  • Based on 1,379 reviews
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Availability: In Stock.
Fulfilled by Amazon
Arrives Tuesday, May 5
Order within 11 hours and 58 minutes
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Features

  • plastic
  • Imported
  • Plastic
  • Imported
  • 120 volt hard wired carbon monoxide alarm wires directly into your home's electrical system
  • Electrochemical sensor accurately detects carbon monoxide
  • Microprocessor controlled to minimize false alarms

Description

Get alerted to dangerous carbon monoxide leaks with the First Alert CO5120BN Hardwired Carbon Monoxide Alarm with Battery Backup. This carbon monoxide detector uses an advanced electrochemical carbon monoxide sensor that accurately detects elevated CO levels and comes equipped with a microprocessor that helps minimize false alarms. The alarm's plug in power connector makes installation quick and easy, while its tamper resistant mounting bracket lock keeps the alarm secure. Featuring a 9 volt battery backup, this unit is designed to offer seamless detection, even in the event of a power outage. An 85 decibel horn sounds if carbon monoxide levels are too high, and a warning chirp notifies you when the battery needs to be replaced. This carbon monoxide alarm can integrate with up to 12 other First Alert or BRK hardwired alarms and up to six other compatible devices such as bells, horns, and repeaters making it ideal for comprehensive coverage of large households or facilities. A latching alarm indicator automatically identifies which unit in the series triggered the alarm. And thanks to the convenient test/silence button, the alarm can be checked easily to ensure it is functioning properly and false alarms can be muted easily. The BRK hardwire carbon monoxide alarm detects dangerous CO gas and allows you peace of mind with its battery backup. Carbon monoxide (CO) is a colorless, odorless, deadly gas. It can be emitted by sources including gas or oil furnaces, gas clothes dryers, water heaters, fireplaces, wood stoves, charcoal grills, gas ranges, and space heaters. A clogged chimney, improper venting, and attached garages can also cause carbon monoxide accumulation. According to the Consumer Product Safety Commission (CPSC), at least one CO alarm should be installed near a home's sleeping area. This BRK alarm is perfect for bedrooms, as well as hallways, and basements. The BRK CO5120BN hardwire CO alarm with battery backup includes these features: Quick plug-in power connector for easy installation. 120-volt AC inter-connectable (with maximum 18 compatible devices). The alarm can be interconnected with up to 12 other compatible smoke alarms and six compatible devices like bells, horns, repeaters and door closers. If one unit triggers an alarm, all smoke alarms in the series will sound. Power indicators show which unit in the series initiated the alarm. Microprocessor controlled for fewer nuisance alarms. Single test/silence button which both silences a non-threatening alarm or low battery warning and allows you to test the unit's functionality. Automatically performs internal test of functionality. Latching alarm indicator which automatically identifies which unit initiated the alarm. Battery drawer lock and mounting bracket lock for tamper resistance. AC power indicator and alarm indicator light. Low battery warning "chirp" and missing battery tab. Swing open battery drawer for easy battery installation. 9-volt battery backup for peace of mind during power outages. All BRK Electronics carbon monoxide alarms are listed to UL Safety Standard 2034 for residential carbon monoxide alarms. Includes 9-volt backup battery. 5-year limited warranty.--Bree NorlanderWhat's in the Box One carbon monoxide alarm, one 9-volt battery, and user's manual

Brand: First Alert


Style: Safety


Power Source: Battery Powered


Color: White


Product Dimensions: 2.09"D x 5.53"W x 5.72"H


Item Weight: 0.55 Pounds


Alarm: Audible


Operating Humidity: 10-95% RH


Sensor Type: Electrochemical


Global Trade Identification Number: 73


Power Source: Battery Powered


Alarm: Audible


Sensor Type: Electrochemical


Operating Humidity: 10-95% RH


Product Style: Safety


Color: White


Item Dimensions D x W x H: 2.09"D x 5.53"W x 5.72"H


Item Weight: 0.55 Pounds


Enclosure Material: Plastic


Brand: First Alert


Model Number: CO5120BN


Global Trade Identification Number: 73


Manufacturer: BRK Brands


UPC: 029054856173


Item Type Name: FIRST ALERT BRK CO5120BN Hardwired Carbon Monoxide (CO) Detector with Battery Backup , White


Built-In Media: FIRST ALERT BRK CO5120BN Hardwired Carbon Monoxide (CO) Detector with Battery Backup , White


Unit Count: 1.0 Count


Manufacturer Warranty Description: Warranty


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Tuesday, May 5

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

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Similar Products

Top Amazon Reviews

    • Great product
Color: White Size: 1 pack Pattern Name: Detector
I ordered this product to replace my old one. It was easy to install, and I just had to plug it in. I did not require an electrician.
Reviewed in the United States on April 13, 2026 by Susan Carter
    • Easy to set up and use
Color: White Size: 1 pack Pattern Name: Detector
This was a replacement of a previous purchased First Alert detector and it fit perfectly. I just attached the wires and it worked right away.
Reviewed in the United States on January 31, 2026 by jeff
    • Great replacement
Color: White Size: 1 pack Pattern Name: Detector
Exactly what I needed to replace what I had .
Reviewed in the United States on March 18, 2026 by Amazon Customer
    • Works fine, easy installation. Derated for lack of compatibility info, made buying a guessing game.
Color: White Size: 1 pack Pattern Name: Detector
Had ordinary smoke detectors around the house, but with recent remodeling, we took advantage of open walls to install hard-wired/connected detectors, and wanted a CO specific unit for the kitchen area (gas stove), where you can't have a smoke detector near the kitchen, for obvious reasons -- to this day, I think of my childhood every time a restaurant claims they make [a recipe] just like mom does, and yet I never hear their smoke detectors going off, LOL. First, the hard wire plug used for First Alert is the same between their smoke, heat, and CO detectors, but the mounting basses are different sizes, to prevent accidentally swapping in an incorrect detector for a another. We learned this last part by putting all the mounts in a tool bag and installing them 'randomly' where each unit would go...easily corrected, but it does make sense for safety sake. Second, there are reviews about First Alert being bought out by, or partnering with, another company that raises the question of compatibility among some models within this product line, hence deliberately buying from Amazon for easy return if needed..I got lucky, all mine worked together just fine. Fit and finish was similar to the smokes, but agree with other reviews that the sticker on CO back is perplexingly oversized, disagree that it holds the unit securely into the base for ceiling mount, as we found the mounting lugs engaged the mounting ring solidly on their own. Personally, I think it was because the stickers were cut slightly larger than the backside of the detector, maybe they used same size circle decal as for their smokes, guess we'll never know... When first installed, it triggered all the other hardwired alarms to go off every several seconds, but unplugging this unit, removing battery, letting it power down completely and then plugging it in before installing battery seems to be the secret handshake for adding a CO-only to their alarm loop. Pressing the test button for a few seconds to reset the capture light finalized the installation process. Haven't had any false CO triggers since. My biggest ding for this product? The same ding as published marketing for the other First Alert detectors: they say it can be installed with XX number of compatible units, but never give any information about which units are actually compatible with which. Why would a company brag about how many can be used, while making it hard for a customer to know which of the several alarm products sold under the First Alert name are or are not compatible with each other??? Based on reviews, some of FA's own hardwired alarms don't play well with others in the product line :( I say an update is needed on their website, at a minimum, to give the customer ease of mind by FA being upfront in compatibility, rather than leaving the customer questioning incompatibility when deciding which units to buy. ... show more
Reviewed in the United States on February 2, 2020 by Penelope Pitstop
    • price
Color: White Size: 1 pack Pattern Name: Detector
good buy
Reviewed in the United States on March 21, 2026 by helen
    • Good Product
Color: White Size: 1 pack Pattern Name: Detector
As expected.
Reviewed in the United States on January 25, 2026 by Dave L
    • Great smoke and CO alarm for the house.
Color: White Size: 1 pack Pattern Name: Detector
This was installed in our home, wired in with a battery back up and we did not know they had a life to them. We started having issues with the alarms, we have 3 beeping on and off for several weeks. We tried changing the batteries, resetting etc. But every time a couple hours, days later it would start again! Most of the time during the night! How frustrating! While looking at the First Alert website we discovered that the alarms have a life to them. So off to buy a replacement to make them quit beeping! It worked for the CO alarm and now we have protection and quiet again! I do recommend the alarms. ... show more
Reviewed in the United States on January 20, 2025 by G&T
    • Check compatibility when ordering!
Color: White Size: 1 pack Pattern Name: Detector
I gave this 5 stars but please read review. I purchased this to interconnect with other BRK First Alert smoke alarms model SMI100-ac but after connecting and testing I had a “flashing red light”. I contacted technical support ( who were awesome!) only to be told I needed the SMICO100-ac to communicate with the SMI100-ac smoke alarms. I returned this alarm and ordered the correct alarm. Fingers crossed…! ... show more
Reviewed in the United States on October 27, 2025 by CK

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