The First Alert Hardwired Combination Smoke/ CO Carbon Alarm is built for easy installation into your home’s electrical system, delivering constant protection you can count on. Even during a power outage, a built-in 9V battery backup keeps your safety uninterrupted. Advanced ionization and electrochemical sensing technologies work together to detect both fast-burning fires and carbon monoxide with speed and accuracy.
Designed with everyday convenience in mind, the alarm features a Mute Button that not only silences false alarms from cooking or steam but also doubles as a quick and easy test function. Backed by a 10-year limited warranty and compliant with new construction standards, this alarm offers dependable safety and peace of mind for years to come.
Electrochemical CO Sensor Alarm Specifications:
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Electrochemical Carbon Monoxide Sensor - the most accurate sensor available as compared to other sensing technologies
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9V Alkaline Battery Backup
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Latching alarm indicator - remembers which unit initiated an alarm
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Temperature Range 40 degrees F (4 degrees C) to 100 degrees F (38 degrees C)
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Humidity Range 10% to 95% relative humidity (RH)
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Audio Alarm 85dB at 10 feet
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Two silence features - can silence the low-battery chirp for up to eight hours or temporarily silence an unwanted nuisance alarm
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End of Life Signal provides audible notification alarms needs to be replaced
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Intelligent Sensing TechnologyTM helps reduce the number of nuisance alarms
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Perfect Mount - allows for easy alignment of alarm
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Dust Cover
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AC Power: Constant Green LED
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DC Power: Intermittent Green LED
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Local Alarm: Red LED flashes rapidly
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Remote Alarm: Red LED out Latching Alarm: Red LED flashes every 5 seconds after local alarm stops
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10-Year Limited Warranty
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Dimension 5.58" dia x 1.97"H
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Listing UL217 & UL 2034 Standards
Easy Installation, Trusted Performance – Built for Today’s Code Requirements
The First Alert SC9120B is the ideal dual sensor smoke and carbon monoxide detector for homes that demand safety, simplicity, and code compliance. This smoke alarm for new construction requirements is designed for fast, frustration-free setup. A large opening in the mounting bracket offers easy access to wiring, while keyhole slots eliminate the need to remove electrical box screws: perfect for pros and DIYers alike.
Featuring a “Quick-Connect” wiring harness and a side-load battery compartment, this alarm allows for battery changes without removing the unit from the ceiling or wall. A convenient battery pull tab keeps power fresh until your home is move-in ready. Plus, two locking features help prevent battery tampering and theft of the unit.
Certified to the latest UL 217 standards and approved by the California State Fire Marshal, the SC9120B emits the new UL-required 85-decibel repeating alarm tone to ensure you're alerted the moment danger is detected.
With a 10-year limited warranty, user-friendly features, and powerful protection, the First Alert SC9120B is the smart choice when you're ready to buy a smoke and carbon monoxide detector that’s reliable, compliant, and built to last. Place your order with Wholesale Home today!

Don't know what type of smoke and carbon monoxide alarm is right for your home? Check out our guide on how to choose the right smoke detector for your home.