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Model # 9120B

Internet # 100065881

Hardwired Interconnected Smoke Alarm with Battery Backup

This item has been discontinued.
The Home Depot no longer carries this specific product.

$12.21 /each



Model # 9120B

Internet # 100065881

The BRK 9120B 120-Volt AC Smoke Alarm with Battery Backup is designed to install faster, perform better, and be even smarter than before. This alarm is 120-Volt AC inter-connectable (with maximum 18 compatible devices), which lets the alarm be interconnected with up to 12 other compatible smoke alarms and six compatible devices like bells, horns, repeaters, and door closers to network a comprehensive system for your home. If one unit triggers an alarm, all smoke alarms in the series will sound. The 9120B includes an ionization sensor which helps detect fast flaming fires that consume combustible materials rapidly. The dust-reducing packaging helps avoid accidental alarms due to contaminants and the 85 dB horn can be inspected with a test button. This unit includes a quick-connect wiring harness for easier installation to your household current and 9-Volt battery backup ensures protection even during power outages or service interruptions. 10-year limited warranty.

  • 120V AC smoke alarm with battery backup
  • 85 dB horn sounds as smoke reaches dangerous levels
  • Can be interconnected with 12 additional BRK and First Alert smoke alarms and 6 compatible devices such as heat alarms for a complete safety system
  • Dust-blocking covers to reduce nuisance alarms associated with particulate contamination
  • Locking pins deter removal
  • A single button tests units functionality and silences nuisance alarms
  • 9-Volt battery backup ensures operation during household current interruption
  • Power indicator lets you see at a glance that the alarm is powered
  • Universal mounting bracket with wide opening for easy wire access
  • Meets UL standards

Info & Guides

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1-UL Listed 


Rated 4.1 out of 5 by 66 reviewers.
Rated 5.0 out of 5.0 by Easy to install We bought two to replace older hard wired smoke alarms. Clear instructions and a very easy installation. They're new so we can't comment yet on their longevity nor performance. December 31, 2013
Rated 5.0 out of 5.0 by Easy to install Placed the new detector in the same bracket as the old one (10 years old) using the same hard wiring Plugged in easily. Toughest part was 77 year old man climbing the step ladder to reach the one in the peak of our vaulted ceiling and that was no fault of the device! May 19, 2015
Rated 5.0 out of 5.0 by Performs as advertised We installed a combination of fifteen interconnected hard-wire and wireless smokes along with three interconnected wireless CO detectors. All eighteen linked together just as advertised and worked flawlessly. Here's to hoping we never need them but if we do, then we can sleep comfortably knowing we're well protected. October 15, 2013
Rated 5.0 out of 5.0 by Great Purchase! This smoke alarm was a direct replacement for those that I had. Easy installation and great price for a high quality item! June 23, 2015
Rated 5.0 out of 5.0 by BRK 9120B Bought our home new in 1999. The smoke alarms installed at that time were BRK 4150B. After 12 years they started to chirp even when new batteries were installed. I have read where dust will make any smoke alarm defective over time. So I replaced all 8 of them with the new BRK 9120B which has the battery backup and which used the same plug, but different base plate. It took me only 30 min to install all 8 of these smoke alarms. I tested them all and they all work perfectly. I then tested with a napkin on fire to see if all 8 of would go off at the same time and they did. I am a happy camper and easy install. February 6, 2014
Rated 4.0 out of 5.0 by Good replacement for earlier smoke detectors I had to replace four 15 year old First Alert smoke detectors. The 9120 had the same footprint, the same wire connection and the instillation was a snap. It took about a half an hour. The 9120 has upgraded features and design improvements that are well worthwhile. February 12, 2013
Rated 3.0 out of 5.0 by smoke alarm purchase Purchased this online since it not available at a store . This is the brand hardwired in my house by the builder. Have had some problems with inserting batteries and had one that only lasted a few years. It is extremely sensitive and I would not have them put in my house if I was building one now. Only good thing is the price. May 12, 2015
Rated 5.0 out of 5.0 by Definitely recommend! Happy with my purchase. Bought two of these alarms. Easy to install. Very easy to change back-up battery. No false alarms. January 10, 2014
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