BRK SC9120B Smoke/Carbon Monoxide Alarm, Hardwired, Battery Backup

SKU: 90109
Brand: BRK Model: SC9120B Condition: New

BRK SC9120B Smoke Alarm

Regular Price: $47.99
On Sale: $33.60
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View All BRK Carbon Monoxide & Smoke Alarm


The BRK SC9120B combination smoke/carbon monoxide alarm is state of the art in fire and carbon monoxide prevention. With dual ionization that detects both smoke and carbon monoxide, the SC9120B eliminates the need for two separate devices. Saving time and money with the BRK SC9120B. This combination smoke alarm is a 120V AC/DC wired alarm with a 9V battery backup in the event of power loss.

These units can be interconnected
so if one unit senses smoke, all units alarm

The BRK SC9120B can be interconnected so if one unit senses smoke, all units alarm.

With a state of the art sensing technology, SC9120B reduces the number of false alarms. Its single test/silence button is combined making use extremely easy to use. The BRK SC9120B mounting system is a cinch. It includes a gasket-less base for easy installation and ensures perfect alignment within minutes. 

Complies with UL217, UL2034, CSFM, NFPA 72, NFPA 720, HUD, FHA and other agencies that model their codes after the above agencies Complies with UL217, UL2034, CSFM, NFPA 72, NFPA 720, HUD, FHA codes.


BRK SC9120B® smoke alarm replaces the discontinued BRK smoke alarm models 4120, 4120B, and 86RAC.


  • 9V Battery Backup
  • Dust Cover
  • Easy alignment of alarm
  • End of Life audible notification
  • Installation Ease, Hassle-Free Maintenance
  • Sensing technology reduce the number of false alarms
  • Silences an unwanted nuisance alarm
  • Silences low-battery chirp for up to eight hours
  • Single silence/test Button
  • Specifications

    • Audio Alarm: 85dB at 10 feet
    • CO Sensor: Metal Oxide
    • Humidity Range: 10% to 90% relative humidity
    • Operating Voltage: 120V AC w/ 9V battery back-up
    • Power: .09 Amps
    • Smoke Sensor: Dual chamber ionization
    • Temp Range: 40 degrees F to 100 degrees F
    • Wiring: Quick connect plug with 8" pigtails

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    Questions & Answers

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    Can these BRK alarms be interconnected?

    by Kevin M. on 03-13-2014

    Yes, the BRK SC9120B model has the ability to be interconnected within a circuit of alarms. You can connect up to 17 devices, of which 11 can be smoke alarms and 6 can be alternate devices.

    on 03-17-2014

    My First Alert SCC9120B were all going off, but there was no fire and no carbon monoxide issues. Therefore, I changed all the batteries thinking that was the problem. After installing the new batteries, a few minutes went by and then one of the alarms started three beeps and soon after the other followed. Do I need to reset these alarms after installing new batteries or what would you think my problem may be?

    by Brian H. on 02-23-2014

    Smoke and carbon monoxide detectors have a shelf life of 7-10 years, if it has been longer than that we recommend purchasing new ones. If they have not been installed that long, contact the manufacturer directly to troubleshoot the unit. First Alert phone number: 800-323-9005

    on 03-07-2014

    Does this carbon monoxide and smoke alarm have voice warning?

    by William R. on 02-01-2014

    No, this unit does not have voice warning. The BRK SC7010BV is the unit with voice warning.It can be found here:

    on 03-17-2014

    do i need to connect this to any A/C SOURCE OR the battery is all i need? AND I AM LOOKING DETECTORS FOR A SCHOOL

    by Kenneth.e.m H. from Antigua and Barbuda on 05-02-2013

    The unit should be hardwired directly to the home/business. Though the battery will power the unit by itself.

    on 05-02-2013

    do i need to connect this to any A/C SOURCE OR the battery is all i need?

    by Kenneth.e.m H. from Antigua and Barbuda on 05-02-2013

    This unit is wired directly to your home. The battery will also power the unit by itself.

    on 05-02-2013

    Is the BRK9120B a direct replacement for the SC6120B ?

    by Kenneth B. on 04-09-2013

    The 9120 Series will replace the SC6120B model

    on 04-09-2013

    Will this SC9120B EASILY replace the old 86RAC? Does it have the same hardwire plug so I can use the old plug? How about the hardware on the ceiling to attach it?thanks in advance! Andy.

    by andrew K. on 04-05-2013

    The 86 RAC is Replaced by the BRK 9120B.

    on 04-05-2013
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