Free Shipping and BOPIS


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

You will need Adobe® Acrobat® Reader to view PDF documents. Download a free copy from the Adobe Web site.


Product Depth (in.) 
Product Height (in.) 
Product Width (in.) 
Alarm Sensor Type 
Alarm Type 
Alarm/Detector Features 
No Additional Features 
Commercial / Residential 
Commercial / Residential 
Connector/Contact Type 
Power Source 
Voltage (volts) 
Warranty / Certifications
Certifications and Listings 
1-UL Listed 


Rated 4.2 out of 5 by 77 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 Smoke detector replacement Worked great and was comparable with existing wiring. Should stick in stores, not mail order only. October 29, 2015
Rated 5.0 out of 5.0 by Great Purchase Great product and a great price. Had the originals for 10 years. Expect these to last 10 years also. October 20, 2015
Rated 4.0 out of 5.0 by Smoke defector-easy to install Cable connector matched old smoke detectors, but baseplate different. Easy to install new baseplates, no new holes needed. Plugged in, attached to new baseplate and installed with new battery. 4 minutes each replacement... So far, happy with them! October 13, 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 Simple & Easy-to install The product was easy to install and it works properly. I saved at least $100 by purchasing and installing rather than calling an service person. September 22, 2015
Rated 5.0 out of 5.0 by Smoke Alarms I enjoyed a competetive price while finding it easy to shop at Home These were replacement alarms and very easy to install. September 15, 2015
Rated 4.0 out of 5.0 by So far so good We installed this product only a week ago and so far we have had neither false alarms nor real alarms. One needs at least a year to really rate a product like this in a meaningful way to see whether or not this product delivers as promised. The installation process was simple yet not as simple as described in the manual. For an experienced hand it will take about 40 minutes to install half a dozen of these detectors. September 1, 2015
  • 2015-11-26 T12:14:34.165-06:00
  • bvseo_lps, prod_bvrr, vn_prr_5.6
  • cp-1, bvpage1
  • co_hasreviews, tv_77, tr_77
  • loc_en_US, sid_100065881, prod, sort_default
2 3 4 >>