---
product_id: 606651014
title: "First Alert SMI100-AC, Hardwire Interconnect Smoke Alarm with Battery Backup, 3-Pack"
brand: "first alert"
price: "$129.30"
currency: USD
in_stock: true
reviews_count: 13
category: "First Alert"
url: https://www.desertcart.us/products/606651014-first-alert-smi100-ac-hardwire-interconnect-smoke-alarm-with-battery
store_origin: US
region: United States of America
---

# Hardwired with battery backup Interconnects all alarms instantly Quick Connect Plug for easy install First Alert SMI100-AC, Hardwire Interconnect Smoke Alarm with Battery Backup, 3-Pack

**Brand:** first alert
**Price:** $129.30
**Availability:** ✅ In Stock

## Summary

> 🔥 Stay ahead of danger with smart simplicity ⚡

## Quick Answers

- **What is this?** First Alert SMI100-AC, Hardwire Interconnect Smoke Alarm with Battery Backup, 3-Pack by first alert
- **How much does it cost?** $129.30 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.us](https://www.desertcart.us/products/606651014-first-alert-smi100-ac-hardwire-interconnect-smoke-alarm-with-battery)

## 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

- • **Effortless Installation:** Quick Connect Plug means no rewiring headaches—upgrade in minutes.
- • **Power Outage Protection:** Battery backup keeps you protected even when the power’s out.
- • **Sleek & Reliable Design:** Low-profile, solid build blends seamlessly while delivering loud, clear alerts.
- • **Precision Detection Tech:** Reduces false alarms from cooking smoke—peace of mind without the nuisance.
- • **Whole-Home Early Warning:** Interconnect feature ensures all alarms sound together for maximum safety.

## Overview

The First Alert SMI100-AC is a 3-pack hardwired smoke alarm system featuring advanced Precision Detection technology to minimize false alarms, a battery backup for uninterrupted protection, and an easy Quick Connect Plug for hassle-free installation. Its interconnect capability ensures all alarms sound simultaneously, providing comprehensive early fire warnings throughout your home.

## Description

The First Alert SMI100-AC Hardwire Interconnect Smoke Alarm with Battery Backup meets new industry standards utilizing First Alert's Precision Detection advance sensing technology. This hardwire smoke alarm is easy to install and replace existing alarms with no need to rewire. Plus interconnect compatible alarms to create a whole home alarm system to help provide an early warning.

Review: Good replacement alarm with simple install and battery backup - I got this as a replacement for an older hardwired smoke alarm, and it was pretty straightforward to swap in. The included quick connect plug made the setup easier, and it fit nicely once mounted. I also like that it has battery backup, so it still gives some peace of mind during a power outage. One thing I appreciated is that it is made to reduce nuisance alarms from normal cooking smoke, which is honestly a big deal if your old detector was too sensitive. The test/silence button is easy to reach, and the alarm feels solid, not flimsy or cheap. It also has the interconnect feature, so compatible alarms in the house can sound together. This is not a fancy smart unit, but for a dependable hardwired smoke alarm, it does the job well. Price felt fair, install was easy, and overall it seems like a solid upgrade from older builder-grade detectors.
Review: Easy Install and Setup - Upgrading our home’s smoke alarms to this 3-pack was a smooth and worthwhile improvement. From start to finish, the process was much easier than I expected. Installation was straightforward, especially if you’re replacing existing hardwired units. The wiring harness connected cleanly, and the mounting brackets lined up without any hassle. Once installed, setup was quick—everything synced as expected with the interconnect feature, so when one alarm is triggered, they all sound. That added level of coverage brings real peace of mind. The battery backup is another big plus. It’s reassuring to know the alarms will still function during a power outage without needing to think about it. The access for the battery compartment is simple and user-friendly, which makes future maintenance easier. I also appreciate the clean, low-profile design. It blends into the ceiling without drawing attention, but still feels solid and well-built. The test/reset button is easy to access, and the alarm itself is loud and clear—exactly what you want in an emergency. Overall, this set delivers on reliability, ease of installation, and essential safety features. If you’re looking to replace older hardwired alarms or upgrade to a system with interconnect capability, this is a practical and dependable choice that doesn’t overcomplicate the process.

## Features

- First Alert's Precision Detection advanced sensing technology complies with new industry standards to reduce cooking nuisance alarms and provides early warning in the event of a home fire emergency
- Through early warning interconnect, when one alarm sounds, all compatible alarms will soun
- Battery backup provides continuous protection during power outages
- Alarm indicator visually identifies the unit that initiated the alarm
- Quick Connect Plug included allows for easy installation with no need to rewire

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B0CJLMM1TQ |
| Alarm | Vibration |
| Best Sellers Rank | #201 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #2 in Smoke Detectors & Fire Alarms |
| Brand | First Alert |
| Built-In Media | Easy Adapter Plug, 9V Alkaline Battery |
| Color | White |
| Customer Reviews | 4.6 out of 5 stars 2,140 Reviews |
| Item Dimensions D x W x H | 5"D x 5"W x 5"H |
| Item Type Name | Smoke Alarm |
| Item Weight | 0.61 Pounds |
| Manufacturer | Resideo |
| Mfr Part Number | SMI100-AC |
| Model Number | SMI100-AC |
| Number of Items | 3 |
| Power Source | Corded Electric |
| Product Dimensions | 5"D x 5"W x 5"H |
| Product Style | Precision Detection |
| Sensor Type | Ionization |
| Style | Precision Detection |
| UPC | 029054022479 |
| Unit Count | 3.0 Count |

## Product Details

- **Alarm:** Vibration
- **Brand:** First Alert
- **Color:** White
- **Item Weight:** 0.61 Pounds
- **Manufacturer:** Resideo
- **Number of Items:** 3
- **Power Source:** Corded Electric
- **Product Dimensions:** 5"D x 5"W x 5"H
- **Sensor Type:** Ionization
- **Style:** Precision Detection

## Images

![First Alert SMI100-AC, Hardwire Interconnect Smoke Alarm with Battery Backup, 3-Pack - Image 1](https://m.media-amazon.com/images/I/71hBZ+xWU9L.jpg)

## Available Options

This product comes in different **Pattern, Size, Style** options.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Good replacement alarm with simple install and battery backup
*by Y***N on April 2, 2026*

I got this as a replacement for an older hardwired smoke alarm, and it was pretty straightforward to swap in. The included quick connect plug made the setup easier, and it fit nicely once mounted. I also like that it has battery backup, so it still gives some peace of mind during a power outage. One thing I appreciated is that it is made to reduce nuisance alarms from normal cooking smoke, which is honestly a big deal if your old detector was too sensitive. The test/silence button is easy to reach, and the alarm feels solid, not flimsy or cheap. It also has the interconnect feature, so compatible alarms in the house can sound together. This is not a fancy smart unit, but for a dependable hardwired smoke alarm, it does the job well. Price felt fair, install was easy, and overall it seems like a solid upgrade from older builder-grade detectors.

### ⭐⭐⭐⭐⭐ Easy Install and Setup
*by H***H on March 25, 2026*

Upgrading our home’s smoke alarms to this 3-pack was a smooth and worthwhile improvement. From start to finish, the process was much easier than I expected. Installation was straightforward, especially if you’re replacing existing hardwired units. The wiring harness connected cleanly, and the mounting brackets lined up without any hassle. Once installed, setup was quick—everything synced as expected with the interconnect feature, so when one alarm is triggered, they all sound. That added level of coverage brings real peace of mind. The battery backup is another big plus. It’s reassuring to know the alarms will still function during a power outage without needing to think about it. The access for the battery compartment is simple and user-friendly, which makes future maintenance easier. I also appreciate the clean, low-profile design. It blends into the ceiling without drawing attention, but still feels solid and well-built. The test/reset button is easy to access, and the alarm itself is loud and clear—exactly what you want in an emergency. Overall, this set delivers on reliability, ease of installation, and essential safety features. If you’re looking to replace older hardwired alarms or upgrade to a system with interconnect capability, this is a practical and dependable choice that doesn’t overcomplicate the process.

### ⭐⭐⭐⭐⭐ Easy to install
*by A***R on March 22, 2026*

This smoke alarm gives great peace of mind and works exactly as expected. Hardwired with backup Continuous power with battery backup for safety. Interconnect feature All alarms sound together, which is a huge plus. Easy installation Straightforward setup and fits standard wiring. Dependable brand First Alert is known for quality and reliability. Bottom line: A dependable, no hassle smoke alarm that’s perfect for home safety. Highly recommend.

## Frequently Bought Together

- First Alert SMI100-AC, Hardwire Interconnect Smoke Alarm with Battery Backup, 3-Pack
- First Alert SMICO100-AC Interconnect Hardwire Combination Smoke & Carbon Monoxide Alarm with Battery Backup, 1-Pack

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*Product available on Desertcart United States of America*
*Store origin: US*
*Last updated: 2026-07-23*