First Alert Hardwired Smoke Alarm with Battery Backup - 9120B

  • First Alert Hardwired Smoke Alarm with Battery Backup - 9120B
  • First Alert Hardwired Smoke Alarm with Battery Backup - 9120B
  • First Alert Hardwired Smoke Alarm with Battery Backup - 9120B
  • First Alert Hardwired Smoke Alarm with Battery Backup - 9120B
  • First Alert Hardwired Smoke Alarm with Battery Backup - 9120B
  • First Alert Hardwired Smoke Alarm with Battery Backup - 9120B
  • First Alert Hardwired Smoke Alarm with Battery Backup - 9120B
  • First Alert Hardwired Smoke Alarm with Battery Backup - 9120B
Ionization Wired In Smoke Detector
Availability: In Stock
In-Stock Notification Sign Up

To be notified when this item is back In Stock, please enter your Email Address below:

Regular: $29.95
Price: $12.59
You Save: $17.36 (57% Off)
Quantity

Hardwired Smoke Alarm with Battery Backup:

Designed to help promote household safety, the First Alert 9120B Hardwired Smoke Alarm with Battery Backup can provide a vital early warning of fire. This hardwired smoke detector uses an ionization smoke sensor to reliably detect smoke from hot, fast-flaming fires.

Ionization Sensor Reliably Detects Flaming Fires

The First Alert 9120B Hardwired Smoke Alarm with Battery Backup comes equipped with an ultra-reliable ionization sensor to provide the earliest possible warning of a fast-flaming fire. The sensor is optimized to detect flaming fires, such as those caused by paper, kitchen grease, and other fast-combusting materials.

Gasket-less for Easy Installation

To facilitate hassle-free installation, this smoke alarm features a streamlined mounting system with a gasket-less base. The mounting bracket keeps the alarm secure over a wide rotation range while maintaining perfect alignment. The alarm also comes with a dust cover to keep the unit clean during construction. AC-powered smoke alarms must be installed in accordance with all local electrical codes.

Battery Backup for Detection During a Power Outage

This smoke alarm is designed for hardwired installation, but it also features a battery backup that helps ensure continued functionality in the event of a power outage. The unit comes with a 9-volt battery and features a pivoting, easy-to-access battery drawer that allows you to replace the battery without dismounting the alarm.

Works in Tandem with Other First Alert Alarms

In addition to functioning independently, this smoke alarm can also integrate with up to 12 other First Alert or BRK hardwired alarms for coverage of larger spaces. It also integrates with up to six other compatible devices, such as bells, horns, and repeaters. If one alarm in the series is triggered, they will all sound. The alarm features a latching indicator to identify which unit triggered the alarm, alerting you to the area of danger.

First Alert Smoke Alarm 9120B

Recommended replacement for the following obsolete models:

BRK 4120B
BRK 4120SB
BRK 86RAC
First Alert SA4120B
First Alert SA4121B
First Alert SA4919B

Product Details
  • Ionization smoke sensor is optimal for detecting fast flaming fires.
  • Loud 85dB alarm.
  • Tamper resistant locking pins.
  • Single button silence/test.
  • 120V AC power with 9V battery backup (included) to keep alarm functioning during power outage.
  • Open mounting design for easy installation with side load battery compartment for quick replacement.
  • Interconnectable up to 18 units (12 smoke, 6 CO/heat/relay).
  • Emits T3 Pattern.
  • 10 Year Limited Warranty.
  • Product Dimensions (LxWxH): 5.6 x 1.9 x 5.6 in.
  • Product Weight: .60 lbs.
Product Specs
UPC:
029054513014
MPN:
9120B

How to Install First Alert 9120B Hardwired Smoke Alarms:

In this guide, we'll be showing you how to install First Alert Hardwired Smoke and Carbon Monoxide Alarms. Here are a few items you'll need before starting the installation process: Needle-nose pliers or utility knife, screwdriver, wire stripper, wire nuts and a ladder.

Hardwired Smoke or Carbon Monoxide Alarm Requirements:

  • 120V household electrical circuit (unswitched 120VAC)
  • Standard wiring junction box to a 4 in. (10 cm) size, on either the ceiling or wall
  • Selecting an appropriate location to install your smoke and carbon monoxide alarms (see below guidelines for additional information):
    first alert smoke alarm install guide
    • When installing an alarm on the wall, the top edge of an alarm should be placed between 4 in. (100 mm) and 12 in. (300 mm) from the wall/ceiling line.
    • When installing an alarm on the ceiling, place the alarm as close to the center as possible.
    • In either case, install the alarm at least 4 in. (100 mm) from where the wall and ceiling meet.
    • First Alert Smoke Alarm FAQs
    • First Alert Carbon Monoxide Alarm FAQs

Connecting First Alert Hardwired Alarms to 120V Wiring

To begin, turn off power at the junction box and connect your alarm to the building's electrical wiring.

  1. Locate the junction box and turn off power
  2. Remove the power connector from the new alarm's packaging
  3. Using wire nuts, attach the hot (black), neutral (white), and interconnect (orange) wires
first alert smoke alarm hardwired install guide
first alert wired in smoke alarm install guide
Black wire
(hot)
Attach to black wire on power connector
White wire
(neutral)
Attach to white wire on power connector
Orange wire
(interconnect)

Standalone (single-station) alarm: This wire is not needed; tuck the orange wire into the junction box.

Interconnected alarms:

  • Strip 1/2 in. from the orange wire on the connector
  • Use a wire nut to attach it to the orange wire in the junction box (see image below).

Mounting First Alert Hardwired Alarms

  1. Secure the mounting bracket to the ceiling or wall using screws (included in the package)
  2. Insert the power connector into the plug on the back of your alarm
  3. Tuck any hanging wires into the junction box
  4. Position the base of the alarm onto the bracket and turn it clockwise until it's secured
  5. Remove the pull-tab to activate the backup battery
first alert carbon monoxide alarm install guide
first alert smoke and co detector install guide

Installing Additional and/or Interconnecting First Alert Hardwired Alarms

If you are installing more smoke or carbon monoxide alarms, you'll want to repeat the process throughout the building. Interconnected smoke and co alarms must meet all requirements:

  • The same fuse or circuit breaker must power all interconnected alarms.

  • Up to 18 compatible detectors can interconnect, with a limit of 12 smoke alarms.

  • The total length of wire interconnecting the alarms should be less than 1,000 ft. (300 meters). This type of wire is commonly available at hardware and electrical supply stores.

  • All wiring must conform to all local electrical codes and NFPA 70 (NEC). Refer to NFPA 72, NFPA 101, and your local building code for more information.

  • Interconnect wiring diagram:

first alert alarm install guide

If you have any doubts or reservations about these interconnect requirements, please contact an experienced electrician to install your wiring and hardwired alarms.


Restoring Power and Testing Hardwired Alarms

Once you've installed your hardwired alarms, you'll want to restore power to the junction box. Under regular operation, the power indicator light on the alarm will shine/blink to indicate that it is receiving AC power.

Here's how you can test standalone or interconnected alarms:

  • Standalone Alarms: Press and hold the Test/Silence button until the unit triggers an alarm.

  • Interconnected Alarms: Press and hold the Test/Silence button until the first unit triggers an alarm. All interconnected detectors should sound off. Repeat this process to test each alarm in the interconnected series.

Q: What is the proper placement of smoke alarms?
A: It is important that you have the proper placement for your smoke alarms. Install your alarms at least 20 feet from appliances like furnaces and ovens, which produce combustion particles. Alarms should be at least 10 feet from high humidity areas like showers and laundry rooms, and at least 3 feet from heat/AC vents. Be sure to install a smoke alarm in each bedroom, one at the top of each stairwell, and one on every level.

Q: Why doesn't my smoke alarm sound when I push the test button?
A: It is important that you frequently test your smoke alarms. When you are testing your smoke alarm, there are a number of reasons why the alarm might not sound:
  • You may not be holding the test button down long enough. Try holding it down for up to 10 seconds (20 seconds on photoelectric models) .
  • Your battery may not be installed properly or snapped all the way in place. Even if the alarm sounded briefly when the battery touched the terminals, you still need to make sure it is snapped securely in place. If the battery is loose, in cannot power the smoke alarm properly. After installing new batteries, be sure to test your smoke detector.
  • Your AC power may not be on. AC and AC/DC units will have a power indicator light (red or green) that shines continuously when they are receiving electrical power.
  • If you have a 10-Year model, the smoke alarm may not have been properly activated. If the tab broke away before the alarm was activated, you can use a toothpick to move the switch over to test the alarm.

Q: Why does my smoke alarm go off when I install a battery or turn on the AC power?
A: It is normal for smoke alarms to go off and sound briefly (up to 5-10 seconds) when you install a new battery or when they are powered up. If the alarm continues to go off and no smoke is present, the cause may be one of the following:
  • There may be insufficient battery power, try new batteries.
  • Problems with voltage or insufficient electrical power (brown out) may cause a continuous weak sounding alarm. For AC or AC/DC models, temporarily disconnect power at the service panel until the brown out is over. If you do not restore the AC power, your smoke alarms cannot warn you of a fire.
  • Incompatible warning device. If an incompatible alarm or auxiliary device is linked into a series of AC or AC/DC smoke alarms it may cause the system inadvertently go off.

Q: I lost my First Alert smoke alarm owner's manual. How can I get a new one?
A: First Alert smoke alarm owner's manuals are available online for download at no cost. Find your alarm in our Smoke Alarms section.

Q: Why does the National Fire Protection Association (NFPA) recommend that home smoke alarms be replaced after 10 years?
A: Smoke alarms have a limited life. Although each smoke alarm and all of its parts have passed many stringent tests and are designed to be as reliable as possible, any of these parts could fail over time. Therefore, you must test the devices weekly. The unit should be replaced immediately if it is not operating properly. The performance of smoke alarms older than 10 years is simply not reliable. To ensure your family's safety, all carbon monoxide and smoke/CO combination alarms need to be replaced every 5-7 years. All smoke alarms need to be replaced every 10 years.

First Alert 9120B Hardwired Smoke Alarm with Battery Backup Videos
If you are interested in ordering a large quantity of items you may qualify for volume pricing discounts. Volume Discount Pricing is a great way for customers to save big on large, bulk orders of most items available in our store. Please send a bulk order request to our friendly sales staff so they may create a quote and provide personal service for your order! You will receive a response within 1-2 business days and our office hours are Monday through Friday, 8am-5pm CST.
We make it as easy as possible to ensure you get the lowest prices available:
  • Let us know what products & the quantities you are interested in.
  • Get a detailed quote from a dedicated sales rep.
  • Our warehouse ships directly to you.
  • You enjoy the savings & are now a preferred customer.
Send A Request Now
Direct From Warehouse Pricing bulk purchase, wholesale pricing

Customer Reviews

Write A Customer Review Review

5

Average score based on 573 reviews

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5
First Alert 9120B Hardwired Smoke Alarm with Battery Backup Reviews

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Smoke Detectors

Reviewed: 07/28/2021 by Crystal S

Very quick service

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Very good

Reviewed: 07/18/2021 by SHIYAN P

Very good.

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Exact fit as old

Reviewed: 07/12/2021 by Diane H

Easy to order and exact fit for replacement

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Exact fit as old

Reviewed: 07/12/2021 by Diane H

Easy to order and exact fit for replacement

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Smoke Alarm

Reviewed: 07/12/2021 by Nancy B

Good product delivered in a timely manner

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5first alert hardwired smoke alarm 9120B

Reviewed: 07/01/2021 by JAIME C

EXCELLENT ITEM !!!

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Easy to swap detector

Reviewed: 06/30/2021 by Jon E

Bought this to replace a previously installed detector of the same model. Very easy. Simply unplugged the old one and plugged in the new one. Done in less than five minutes!

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5First Alert Hardwired Smoke Alarm with Battery Backup - 9120B

Reviewed: 06/28/2021 by Ravi S

I had no issues with this product. I had purchased many First Alert Smoke Alarm products and a couple of Carbon Monoxide detector products. Highly recommend these products.

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Smoke Detectors

Reviewed: 06/28/2021 by Mary G

Placed my order and received it quickly. Website was easy to navigate and the entire experience was great!

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Easy Transaction

Reviewed: 06/18/2021 by James R

Easy Transaction & Great Price. Quality Products.

View More Reviews...