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
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View All BRK Carbon Monoxide & Smoke Alarm


The BRK SC9120B smoke/carbon monoxide alarm is a 120V AC/DC, hardwired combination smoke alarm with battery backup. Simply put, the BRK is state of the art in fire and carbon monoxide detection that meets new construction requirements. The BRK combination smoke alarm eliminates the need for two separate devices; saving time and money. With an electrochemical carbon monoxide sensor and dual ionization that detects both smoke and carbon monoxide, you get indutsry leading smoke alarm technology.

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

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


The 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 Sound notification
  • Installation Ease
  • Hassle-Free Maintenance
  • Sensing technology reduce the number of false alarms
  • Silences an unwanted False Alarm
  • Silences low battery chirps for up to 8 hours
  • Single Silence/Test Button


  • Audio Alarm: 85dB at 10 feet
  • CO Sensor: Metal Oxide
  • Humidity Range: 10% - 90% relative humidity
  • 120V AC w/ 9V battery Back-Up
  • 09 Amps
  • Dual Chamber Ionization Sensor
  • 40 degrees F to 100 degrees F Operating Temperature
  • 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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