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Internet #202433890

Model #SC9120B

Store SO SKU #1000498953

Hardwired Interconnected Smoke and CO Alarm with Battery Backup

  • Uses ionization technology and an electrochemical sensor
  • Detects smoke and carbon monoxide
  • Hardwired with battery backup
  • View More Details

Product Overview

Marketed to builders, electrical contractors serving single family, multifamily, hotel/motel, RV and manufactured homes channels. The contractor-friendly product and packaging design sets the professional standard. Working smoke alarms cut the risk of dying in a home fire by 50% and that's important because a home structure fire was reported every 86 seconds. Whereas carbon monoxide (CO) is the leading cause of accidental poisoning deaths in America, yet many people don't know they are suffering from CO poisoning until it’s too late. Symptoms of carbon monoxide poisoning are like the flu and you might not even know you're in danger. The SC9120B hardwire alarm comes with 2-in-1 protection to detect CO you can't see, smell or taste in the air, as well as first signs of a potential fire. This alarm works exceptionally well by using ionization sensor technology to detect fast flaming fires that spread quickly. Sources of these fires include cooktop grease or wastebasket fires. It also includes battery backup for power outages and features a Test/Silence button to check if the alarm is functioning properly as well as silence unwanted or nuisance alarms. This BRK SC9120B Hardwire Smoke and Carbon Monoxide Alarm is an essential product in protecting those who matter most.
  • 9-Volt alkaline battery backup
  • Latching alarm indicator - remembers which unit initiated an alarm
  • 2 silence features can silence the low-battery chirp for up to 8-hours or temporarily silence an unwanted nuisance alarm
  • End of life signal provides audible notification alarms needs to be replaced
  • Battery door lock and mounting bracket lock for tamper resistance
  • Low-battery warning chirp and missing battery tab alert you when unit requires a new power source
  • Quick plug-in power connector for easy installation
  • Latching alarm indicator remembers which unit initiated an alarm
  • America's most trusted brand in home safety
  • Click here for more information on Electronic Recycling Programs

Info & Guides

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Product Depth (in.)
2.25 in
Product Height (in.)
5.75 in
Product Width (in.)
5.75 in


Alarm Sensor Type
Alarm Type
Carbon Monoxide,Smoke
Alarm/Detector Features
Battery Back-Up
Battery Type Required
Connector/Contact Type
Fixed or portable
Pack Size
Power Source
Voltage (volts)

Warranty / Certifications

Certifications and Listings
UL Listed

Questions & Answers

Typical questions asked about products:

  • Is the product durable?
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Customer Reviews

  • 4.7
    out of 423 reviews
  • 92% recommend this product
Filter by:
Showing 1-10 of 423 reviews
Interconnected Smoke and Co-alarm with Backup Batt
I purchased this Interconnected Smoke and Co-alarm with Backup Battery as this is the same one I have in my house that needed to be replaced. This is a reliable product and I will continue to purchase it again from Home Depot when needed.
  • Verified Purchase
  • Recommended
EXACT FIT, Manufactured in January 2021 !
Purchased 2 for a set of 8 interconnected in my house. Exact Fit, newly manufactured in 2021, good till 2030 !! I looked everywhere for these and finally found them in stock here. Im very happy. Otherwise I would have had to switch out all 8. hard wired with battery backup.
    • Recommended
    Easy installation and connected into the full house interconnected units easily. Wish it was avai...
    Easy installation and connected into the full house interconnected units easily. Wish it was available in store vs. only online, but pickup at store was easy enough.
    • Verified Purchase
    • Recommended
    1 person found this helpful
    Perfect fit from the replaced unit.
    Perfect fit from the replaced unit.
    • Verified Purchase
    • Recommended
    I am very happy with my purchase! I matched the wires as black-black, white-white, orange-red. ...
    I am very happy with my purchase! I matched the wires as black-black, white-white, orange-red. At first, the detector flashed green every two seconds. I realized that one of the wires wasn't snug in the nut, so after that was fixed it worked perfectly.
      • Recommended
      Easy to install. ...
      Easy to install.
      • Verified Purchase
      Shelf Life for SC9120B First Alert Combo Smoke and Carbon Monoxide Alarm
      Be aware and forewarned when purchasing this product of the manufacture date on the back of the alarm unit. Customer service at First Alert (800-323-9005) tells me that there is a shelf life of only 5 years on units manufactured before May 2011. We have apartment buildings and In January 2016, we purchased eight units from Home Depot for replacement on units that were starting to chirp. The units we purchased had a stamped manufacturing date of April 25, 2011. Here it is August 2016 and we are having to replace all the units we just recently replaced as all the new units started chirping and will not cease chirping even after replacing with new batteries, twice (thinking perhaps the batteries were defective). The batteries are fine. It is the units that are at the end of their shelf life so I am told by customer service at First Alert; and unless I can produce the receipt, First Alert customer service cannot/will not assist me. 2015 taxes were filed and receipts are with accountant. I feel that First Alert should have not only the manufacture date on the back, BUT, should also have the expiration date stamped alongside. Had we known these units have a shelf life/expiration dates, we would not be buying in bulk and replacing expired units with more expired (but new) units. I am also disappointed that the big box stores are selling expired merchandise that should be pulled off the shelves!!!
        50 people found this helpful
        BRK Smoke & Carbon Monoxide Alarm Perfect Solution!
        I replaced two BRK Smoke Alarms with two BRK Smoke & Carbon Monoxide Alarms in our home. They were compatible with the existing multi-alarm system and matched perfectly in the ceiling. Great solution to adding carbon monoxide alarm capability to our home. The removal of the old smoke alarms and installation of the two new smoke & carbon monoxide alarms was "plug and play"!
        • DIY
        • Verified Purchase
        • Recommended
        Good product
        Good product. Had it shipped to store and picked it up in about 2 weeks
        • Verified Purchase
        • Recommended
        Good quality and Easy to install and works great.
        I replaced my old smoke sensor with this and it is easy to install and works great.
        • Verified Purchase
        • Recommended
        Showing 1-10 of 423 reviews