BRK Hardwired Interconnected Smoke Alarm with Battery Backup-9120B at The Home Depot


Model # 9120B

Internet # 100065881

Hardwired Interconnected Smoke Alarm with Battery Backup

BRK Hardwired Interconnected Smoke Alarm with Battery Backup

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

$14.97 / each


In Stock



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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Alarm Sensor Type  Ionization  Alarm Type  Smoke 
Alarm/Detector Features  No Additional Features  Assembled Depth (in.)  2 in 
Assembled Height (in.)  5.63 in  Assembled Width (in.)  5.5 in 
Battery Back-Up  Yes  Battery Power Type  Alkaline 
Battery Size  9-volt  Certifications and Listings  1-UL Listed 
Commercial / Residential  Commercial / Residential  Connector/Contact Type  4-Wire 
Electrical Product Type  Smoke Detector  Included  Batteries 
Returnable  90-Day  Voltage (volts)  120 


Rated 4 out of 5 by 53 reviewers.
Rated 5 out of 5 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 out of 5 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 out of 5 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 5 out of 5 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
Rated 1 out of 5 by Beeping in middle of night for no reason I had 6 of these installed when I added on to my house in late 2011, and not quite 3 years later the one in my bedroom goes off several times a week (not the full alarm, but 3 or 4 full beeps about 5-10 seconds apart). It doesn't trip the other units. Sometimes this happens in the daytime, but mostly in the middle of the night when I'm trying to sleep. I've tested the battery, and it's fine. You can't just leave the battery out, because then it does the short, persistent chirping thing. I've lost so much sleep on this and am trying to unplug it (but the plug on this one is very tight and I can't get it detached). The easy solution would be to buy a new one of the same model so it would "plug and play", but I am hesitant to waste money on another. I've had smoke detectors in my house for 25 years and never had this problem with the previous ones we've used (they only went off if we were burning our food in the kitchen). What a pain in the butt! October 10, 2014
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