---
product_id: 369812453
title: "FIRST ALERT9120B Smoke Detector, Hardwired Alarm with Battery Backup, 6-Pack"
brand: "first alert"
price: "KSh81269"
currency: KES
in_stock: true
reviews_count: 5
url: https://www.desertcart.co.ke/products/369812453-first-alert9120b-smoke-detector-hardwired-alarm-with-battery-backup-6
store_origin: KE
region: Kenya
---

# Battery Backup Hardwired 85dB Alarm FIRST ALERT9120B Smoke Detector, Hardwired Alarm with Battery Backup, 6-Pack

**Brand:** first alert
**Price:** KSh81269
**Availability:** ✅ In Stock

## Summary

> 🔥 Stay Alert, Stay Safe! 🔥

## Quick Answers

- **What is this?** FIRST ALERT9120B Smoke Detector, Hardwired Alarm with Battery Backup, 6-Pack by first alert
- **How much does it cost?** KSh81269 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.co.ke](https://www.desertcart.co.ke/products/369812453-first-alert9120b-smoke-detector-hardwired-alarm-with-battery-backup-6)

## Best For

- first alert enthusiasts

## Why This Product

- Trusted first alert brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Ultimate Safety:** Protect your home with the most trusted smoke alarms.
- • **Proven Reliability:** Rigorously tested to meet UL standards for your peace of mind.
- • **Quick Installation:** Universal mounting brackets for hassle-free setup.
- • **User-Friendly Design:** Single test/silence button for effortless operation.
- • **Seamless Connectivity:** Connects with other First Alert alarms for comprehensive coverage.

## Overview

The First Alert 9120B Smoke Detector is a hardwired alarm system with battery backup, designed to provide reliable smoke detection from fast flaming fires. This 6-pack ensures comprehensive coverage throughout your home, featuring an 85 decibel alarm, easy installation, and seamless connectivity with other compatible smoke detectors. With a user-friendly design and rigorous testing to meet UL standards, it’s the ultimate choice for home safety.

## Description

FIRST ALERT9120B Smoke Detector, Hardwired Alarm with Battery Backup, 6-Pack

## Features

- Note: A loose neutral (white wire) connection within the home junction box could prompt a device malfunction
- Equipped with an ionization sensor, this smoke alarm reliably detects smoke from fast flaming fires and alerts you with an 85 decibel alarm
- To ensure complete protection make sure to place one on each level of your home and in each bedroom
- Can connect to other compatible BRK or First Alert smoke detectors, to ensure all alarms will sound when smoke is detected
- Simple to use, with a single test/silence button, and side load battery compartment; Tamper resistant locking brackets and universal mounting brackets make installation easy
- Rigorously tested to meet UL standards. Emits T3 pattern
- Keep your family safe with this 6 pack of hardwired smoke alarms; the battery backup means constant monitoring, even if there's a power failure
- Faster turnarounds on job sites with the easy-to-install, most-trusted alarms in home safety. easy-to-access battery drawer that allows you to replace the battery without dismounting the alarm
- First Alert has been the most trusted brand in home safety since launching the first residential smoke alarm in 1958 (Based on a First Alert Brand Trust Survey in February 2018)

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B000KKHWLU |
| Alarm | Audible |
| Batteries | 2 AA batteries required. (included) |
| Batteries Included? | Yes |
| Batteries Required? | Yes |
| Battery Cell Type | Zinc Carbon |
| Best Sellers Rank | #8,357 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #25 in Smoke Detectors & Fire Alarms |
| Brand | First Alert |
| Color | White |
| Customer Reviews | 4.7 4.7 out of 5 stars (11,612) |
| Date First Available | January 1, 2008 |
| Global Trade Identification Number | 00029054121134, 10029054121131 |
| Included Components | First Alert 9120B Smoke Detector, Hardwired Alarm with Battery Backup, 6-Pack |
| Is Discontinued By Manufacturer | No |
| Item Package Quantity | 1 |
| Item Weight | 3.34 pounds |
| Item model number | 9120B6CP |
| Manufacturer | First Alert |
| Material | Plastic |
| Number of Items | 6 |
| Operating Humidity | 10-95% RH |
| Part Number | 9120B6CP |
| Pattern | 9120B6CP |
| Power Source | Battery Powered |
| Product Dimensions | 1.9"D x 5.6"W x 5.6"H |
| Sensor Type | Ionization |
| Size | 6-Pack |
| Smart Home Compatibility | Not Smart Home Compatible |
| Style | Standard Detection |
| UPC | 111012470009 029054121134 |
| Voltage | 120 Volts |
| Warranty Description | 10 year |

## Product Details

- **Alarm:** Audible
- **Brand:** First Alert
- **Color:** White
- **Global Trade Identification Number:** 00029054121134, 10029054121131
- **Material:** Plastic
- **Operating Humidity:** 10-95% RH
- **Power Source:** Battery Powered
- **Product Dimensions:** 1.9"D x 5.6"W x 5.6"H
- **Sensor Type:** Ionization
- **Style:** Standard Detection

## Images

![FIRST ALERT9120B Smoke Detector, Hardwired Alarm with Battery Backup, 6-Pack - Image 1](https://m.media-amazon.com/images/I/71P8xUZFBFL.jpg)
![FIRST ALERT9120B Smoke Detector, Hardwired Alarm with Battery Backup, 6-Pack - Image 2](https://m.media-amazon.com/images/I/61xmQ8oo1LL.jpg)
![FIRST ALERT9120B Smoke Detector, Hardwired Alarm with Battery Backup, 6-Pack - Image 3](https://m.media-amazon.com/images/I/71Hesxpc2EL.jpg)
![FIRST ALERT9120B Smoke Detector, Hardwired Alarm with Battery Backup, 6-Pack - Image 4](https://m.media-amazon.com/images/I/71SKYwB-NfL.jpg)
![FIRST ALERT9120B Smoke Detector, Hardwired Alarm with Battery Backup, 6-Pack - Image 5](https://m.media-amazon.com/images/I/61XcWXuGmUL.jpg)

## Questions & Answers

**Q: How do you silence this alarm? Apparently the low battery notification only starts after midnight and WILL NOT STOP unless you have another battery.**
A: I am certain this applies to all brand and model of smoke detectors.  Once the low battery beep starts happening, which is always just as your falling off to sleep, there is only one way to stop it.  Follow the steps outlined below.
1 - put all weapons in your house under lock and key. (this is for the safety of you your family and the manufacturer of the smoke detectors).
2 - Give the key to someone you can trust and that your are not capable of overpowering.
3 - Find the smoke detector that is beeping. Tip, its never the one you are standing beneath look up at.
4 - Ice your foot because by now you have kicked several walls, doors and furniture.
5 - Assuming you have located the guilty smoke detector and have not yet burned down your home or found a way to access your weapons in step 1, move to step 6.
6 - Take the guilty smoke detector(s) into the garage and smash them into as many pieces as possible with the biggest hammer you own.
7 - Most likely you have stopped the regular beeping but every 20 to 40 minutes or so you will still hear a beep.
8 - Start a fire in the back yard fire pit and when the fire has reached white hot with glowing red hot coals put the smashed bits and pieces into the fire and let it burn until it burns out on its own.
9 - Take a shower and get dressed because by this time your late for work and haven't slept.
10 - When you get home that evening and hear another beep burn the house but make it look like an accident.

**Q: Can a  BRK Model 92120B smoke detector directly plug in and replace an old BRK Model 4120B smoke detector (without an adapter)**
A: Yes.  I just replaced 2 very old (older than 10 years) BRK Electronics Model 4120B smoke detectors with these newer First Alert/BRK Brand Model 9120B units.  My older units were yellowed with age, so I also replaced the plastic base.  I did reuse the 3 pin electrical connector, as the "old" electrical connector matches the new unit.  The new smoke detectors are functioning/self-testing normally.

**Q: can these be connected together so if one is set off they  all go off?**
A: Have these in my home. House was built about 4 years ago (2017) Came with the house.. One goes off they all go off. They are connected to each other by wire. I did have the one in my bedroom that I had to replace prematurely.  It was just going off for no reason setting the entire house alarms. It was easily identified by the light on it that it was the culprit. Basic troubleshooting taking out of system all was good. I am a 42 year volunteer firefighter,  held a Chief, Captain , Luitenant, Firefighter and other various positions . My opinion,  having them all wired together, so when one goes off they all do is SMART! Been to multiple house fires through all my years and seen where the families on the first floor watching TV while their second floor or basement is burning up. 🔥

**Q: My entire home is equipped with BRK smoke detector (4120 B) and Carbon Monox Det (CO50120B). They need replacing. Will new BRK fit extant casings?**
A: The mount screws will fit but the base plate itself is slightly smaller and you might have to touch up paint. The connectors will fit as well so no need to change those

## Customer Reviews

### ⭐ 







  
  
    Look for another brand or model
  

*by A***Y on Reviewed in the United States on 1 July 2018*

Purchased a six pack for replacements of my 18 year old units, which by the way never gave us any problems. Replaced them all in December of 2017. Three months later (late February) as we were preparing to leave home for an appointment they all started going off and would not stop. Do you know how difficult it is to find which one is causing the false alarm? After running up and down the steps from the basement to the second floor, unplugging all of them (8 total, we also have two photoelectric sensors) I finally found the one causing the problem. I replaced the battery, only to have them go off again a few short minutes later. Ordered a new one and replaced the defect.Fast forward to July 1st, sleeping nicely at 6 am on a Sunday morning and here we go again, they all start chirping. This time it only lasted for about five minutes, enough time for me to run up and down the stairs looking for smoke or fire and the beeping stops. Of course, this wasn't enough time for me to find the defect. Now we get to go to sleep every night wondering when it's going to happen again. At least I have the confidence of knowing that when we're away we have another model hooked directly to our home alarm system, which will give us an alert over our cell phone. I just hope that a false alarm won't drive our parrot absolutely crazy if we're not at home.Time to look for another brand or model.

### ⭐ 







  
  
    I hate this smoke detectors
  

*by J***H on Reviewed in the United States on 19 April 2021*

I hate these with a passion. They are super sensitive, so if I make a tiny amount of smoke on the stove, or in the oven, boom whole house is screaming about it. It is almost impossible to determine which unit has a low battery as they all seem to beep, not often enough (really). The fact that they are hard wired is both good and bad. This is great if there is an actual alarm, because they will all alarm. It is also bad if you ever plan to switch, or they discontinue the model who knows you may need to swap out every alarm. However, they are still 100X better than any smoke detector that want's an internet connection, so whatever... If you are replacing one, do it. If you have to replace a bunch, I would look into finding a better, less exhausting system.

### ⭐ 







  
  
    FALSE ALARMS AT 3am!!!!!!!!!!
  

*by C***D on Reviewed in the United States on 25 January 2020*

I've had 9 of these in my home for over a year. While on the one hand, they seem to be doing their job, on the other hand, what IS their job? To sit quietly by and wait. And if they ever detect smoke, to warn you. Pretty simple.These detectors FAIL.FALSE ALARMS!!!!!!!!!I've never had a smoke detector in my 50 year life give false alarms...until now! These have some MAJOR design defect, because they go off for NO REASON, most often in the middle of the night.I'm not quick to judge either. I've wanted to believe that it's just an anomaly. It started only a few weeks after installation. Alarms going off at 3am or 4am. One night it was in one room, another night a different one. Random and unpredictable. I would reset the specific detector that alerted, then just hope it wouldn't happen again. Sometimes it wouldn't, for weeks. Sometimes it would, the next night. But I was patient, and asked my family to bear with them. Tonight I've simply had enough!!!! 3 times the one in my bedroom went off. 3 times I reset it. Then I disconnected it and set it aside. I've GOT to find another brand. I can't take it anymore with these.If you don't like sleeping peacefully, without your whole family being startled awake at 3am by false alarms, randomly for many nights in a row, with occasional weeks in between, then buy these. But be forewarned. They are the worst smoke detectors I've ever had, and will NEVER BUY FIRST ALERT AGAIN.What kind of product are they producing? One that fails to do its job. What's their advice if you call customer service? Vacuum all 9 detectors every week! REALLY???You gotta be kidding me!!! That's just a bad joke.Seriously, don't decide based on price or ease of installation. Decide based on whether or not you value your sanity.10/6/22 Here's an update...I have removed these detectors when they give a false alarm. I discovered that if I blast them with compressed air, then reinstall, they work normally, with no false alarm...for awhile. Can't say how long, but I've been doing it successfully for most of this year and haven't had any nighttime alarms. Take that for what it's worth...

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*Product available on Desertcart Kenya*
*Store origin: KE*
*Last updated: 2026-03-19*