First Alert BRK Carbon Monoxide Detector - Hardwired CO Alarm

In this review the First Alert BRK Carbon Monoxide Detector (CO5120BN) is assessed as a practical hardwired CO alarm suited to homeowners who want a dependable, low-maintenance safety device. The biggest reason to consider this unit is its reliable electrochemical sensor paired with hardwired 120 volt power and a 9 volt battery backup, which together provide continuous protection even during outages. It is straightforward to install for anyone comfortable with basic wiring and values a microprocessor-controlled alarm that reduces false alarms.

Key Features

• Hardwired 120 volt: Wires directly into the home's electrical system for continuous powered monitoring without relying solely on replaceable batteries.
• Battery backup: The included 9 volt battery keeps the alarm active during power outages so detection continues uninterrupted.
• Electrochemical sensor: The advanced sensor accurately detects carbon monoxide and is less prone to interference than older sensor types.
• Microprocessor control: Electronic processing helps minimize nuisance and false alarms so occupants are alerted only when levels are concerning.
• 85 dB horn: A loud alarm alerts sleeping or distant household members when carbon monoxide levels become dangerous.
• Tamper resistant bracket: The locking mount helps keep the unit securely installed where it will be most effective.

Who It's For

This detector is best for homeowners and renters whose properties already have hardwired alarm systems or who want a permanently powered CO alarm with battery backup. It is a solid choice for those who prioritize accurate detection and a device that integrates into household wiring without frequent battery swaps.

It may be less suitable for people who need a fully portable detector or who cannot or prefer not to perform any wiring; in those cases a plug-in or battery-only model would be easier. Also, buyers who want smart-home connectivity should look elsewhere, as this unit focuses on reliable sensing rather than network features.

Pros & Cons

Pros

• Reliable electrochemical sensor offers accurate CO detection and steady performance.
• Hardwired 120 volt power with 9 volt battery backup ensures continuous protection during outages.
• Microprocessor control reduces false alarms, improving day-to-day usability.
• Easy installation for users comfortable with basic wiring and includes a tamper resistant bracket for security.

Cons

• Some customers report mixed lifespan expectations, so eventual replacement timing can vary.
• Occasional chirp frequency issues have been noted by owners, which can be disruptive at night.

Specifications

Our Verdict

The First Alert BRK CO5120BN is a practical, value-focused hardwired carbon monoxide detector that delivers accurate sensing and reliable backup power, making it a good buy for homeowners who want a low-fuss, permanently powered alarm. It is recommended for installations where continuous protection and minimized false alarms matter most, though those seeking wireless or smart features should consider alternatives.

Frequently Asked Questions

Does this unit work during a power outage?
Yes. The alarm uses a 9 volt battery backup to maintain operation if the 120 volt supply is interrupted.

What sensor technology does it use?
The unit uses an electrochemical carbon monoxide sensor, which provides accurate CO detection and reduced interference.

Is installation difficult?
Installation requires wiring into a 120 volt circuit, so it is straightforward for users comfortable with basic electrical work or a professional installer.