BRK SC9120B First Alert Smoke & Carbon Monoxide Alarm, Hardwired, 9V Battery

Brand: BRK
Model: SC9120B
Condition: New
Warranty: 7 Years
SKU: 90109
4.55 (5 Reviews)
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BRK SC9120B First Alert Smoke/Carbon Monoxide Alarm

Regular Price: $40.99
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The BRK SC9120B First Alert smoke & carbon monoxide alarm is a 120V AC/DC, hardwired smoke and carbon monoxide alarm with battery backup and an 85db horn. This BRK combo smoke & carbon monoxide is designed to reduce false alarms. Capable of being interconnected with up to 18 devices (12 can be smoke alarms) its latching alarm indication recalls which unit triggered the alarm in the series. Its red LED indicator flashes rapidly. Afterwards, the BRK combo alarm stores it into memory and then flashes every two seconds. Simply put, the BRK SC9120B is state of the art smoke and carbon monoxide detection that meets new construction requirements.

Due to its two locking features, the BRK SC9120B smoke and carbon monoxide alarm locks the battery drawer and alarm to the base to prevent authorized tampering. Its ideally suited for apartments, hotels, dorms, or multi-family dwellingsThe First Alert SC9120B BRK smoke and carbon monoxide alarm eliminates the need for two separate devices; saving time and money. Its single test/silence button is combined making it extremely easy to use.

The First Alert 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 smoke alarm can be interconnected so if one unit senses smoke, all units alarm. Connecection to AC power is fast and easy with a quick connect wiring harness.

  • 9V Battery Backup
  • Fast Installation, Minimal Downtime
  • Indicator Lights for Power
  • Interconnectable up 18 Smoke Devices; 12 can be smoke alarms
  • Dust Cover
  • Easy Alignment of Alarm
  • End of Life Sound Notification
  • Hassle-Free Maintenance
  • Photoelectric Sensor Saves Maintenance Calls
  • Silences Unwanted False Alarm
  • Silences Low Battery Chirps For Up to 8 Hours
  • Single Silence/Test Button
  • Alarm Strength 85dB at 10 Feet
  • Dimensions: 5.58" Diameter x 1.97" H
  • Dual Ionization 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
  • Replaces Discontinued BRK smoke alarm models 4120, 4120B, 86RAC
  • Weighs 8.5 ounces
7 year warranty through BRK Electronics
Customer Reviews

Good Replacement source over retail box store

I purchase these wired w/battery in 2011 to replace our original ones from a new construction from 2005. Best price available at the time. Easy to replace when using the same mounting base in a wired system. Now in 7/2016 I have had (2) go bad because they continue to sound even after blowing out with air and replacing 9V battery. Same 5 year life problem when I had to replace all 6 in the house. These fire/smoke and carbon dioxide detectors have a 7 year warranty. You will need to call First Alert customer service instead of Westside and you will get free replacement with or without a slight service/handling charge which is reasonable. Better than buying new again if under warranty. Keep your purchase records and date of manufacture handy for warranty. Might be best to register new replacements them with the manufacture website. There may better or improved protection models, so due your research and method of wiring if you do it yourself. Check your building codes also and follow the instructions.


on 07-08-2016 by Larry

Life saving

Have a small house with these installed throughout. Saved our lives. Alarm sounded gave me time to get up, found the chimney shoot had closed and the gas was left on a little. Thankfully these went off.


on 04-11-2016 by LT

Good product dependable

One of the go to hardwired combo smoke/CO2 devices!


on 01-29-2016 by MMC

great product

I have installed dozens of this model with minimal problems.


on 01-15-2016 by Leon

Couldn't be easier

Ordered it. It came quickly and was a snap to install.


on 12-11-2015 by Thomas

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Questions & Answers

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I'm assuming the BRK 9120 series (SC9120B and 9120B) will replace the old 4919 by using the same quick connect wiring fitting from the old 4919 and just changing the mounting bracket? I need to replace my old 4919 detectors and I want to also get the combined CO detector option.

by Greg C. on 02-19-2015

Yes, the BRK 9120 series is the best replacement for the 4919 series.

on 02-23-2015

This BRK smoke alarm beeps three times and a red light is flashing.

by Melvin T. on 11-19-2014

It may be indicating that it is time to change the battery. However, if the unit is older than 7 years, it will need to be replaced. The shelf life on carbon monoxide detectors is 5-7 years.

on 11-19-2014

How do you check the batteries for the BRK SC9120B?

by Leslie F. on 11-10-2014

The battery compartment for the unit is on the lower left hand side.

on 11-11-2014

How should the BRK 9120B be cleaned?

by Paul B. on 10-20-2014

Per the manufacturer, BRK recommends cleaning the unit out with canned air. It will remove any excess dust without effecting the operation of the unit.

on 10-27-2014

I know the BRK SC9120B is not a direct replacement for the BRK 86RAC. I have 6 smoke detectors and would like to replace 4 with the BRK 9120B regular smoke detectors and 2 with the BRK SC9120B that are smoke and carbon monoxide. It that possible? Are mounting brackets and wiring same?

by Winslow Y. on 10-13-2014

Actually, the BRK SC9120B is a replacement for the discontinued BRK 86RAC as is the BRK 9120B. They are interconnectable with each other. The wiring is the same within all the units, the only thing that needs to be changed with an older model is the plastic mounting bracket.

on 10-13-2014

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
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