--- product_id: 609937867 title: "Hardwire Smoke Alarm | SMI100-AC, 9V Battery Backup" brand: "first alert" price: "R767" currency: ZAR in_stock: true reviews_count: 9 url: https://www.desertcart.co.za/products/609937867-hardwire-smoke-alarm-smi100-ac-9v-battery-backup store_origin: ZA region: South Africa --- # Hardwired with battery backup Interconnects all alarms instantly Quick Connect Plug for no-rewire install Hardwire Smoke Alarm | SMI100-AC, 9V Battery Backup **Brand:** first alert **Price:** R767 **Availability:** ✅ In Stock ## Summary > 🔥 Stay ahead of danger with smart, seamless protection ⚡ ## Quick Answers - **What is this?** Hardwire Smoke Alarm | SMI100-AC, 9V Battery Backup by first alert - **How much does it cost?** R767 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.co.za](https://www.desertcart.co.za/products/609937867-hardwire-smoke-alarm-smi100-ac-9v-battery-backup) ## 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 - • **Visual Alarm ID:** Instantly know which unit triggered the alert—no guesswork - • **Power Outage Proof:** 9V battery backup keeps protection live even when the power’s out - • **Seamless Interconnect:** One alarm sounds, all alarms alert—whole-home safety synced - • **Effortless Installation:** Quick Connect Plug means no rewiring headaches, upgrade in minutes - • **Precision Detection Tech:** Reduces false alarms, so you only react when it counts ## Overview The First Alert SMI100-AC Hardwire Smoke Alarm features advanced Precision Detection technology to minimize nuisance alerts while providing early fire warnings. It interconnects with compatible alarms for whole-home coverage, includes a 9V battery backup for power outage protection, and installs easily with a Quick Connect Plug—ensuring reliable, hassle-free safety. ## 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. ## 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 sound - 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 | |---------------|-------| | Alarm | Smoke Alarm | | Asin | B0CJMN3443 | | Best Sellers Rank | #215 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 4.6 out of 5 stars (2,495) 4.6 out of 5 stars | | Global Trade Identification Number | 10029054022469 | | Item Dimensions D X W X H | 5.6"D x 5.6"W x 1"H | | Item Type Name | Smoke Alarm | | Item Weight | 9.6 ounces | | Manufacturer | Resideo | | Mfr Part Number | SMI100-AC | | Model Number | SMI100-AC | | Number Of Items | 1 | | Power Source | Corded Electric | | Product Style | Precision Detection | | Sensor Type | Ionization | | Unit Count | 1 Count | | Upc | 029054022462 | ## Product Details - **Alarm:** Smoke Alarm - **Brand:** First Alert - **Color:** White - **Global Trade Identification Number:** 10029054022469 - **Item Weight:** 9.6 ounces - **Power Source:** Corded Electric - **Product Dimensions:** 5.6"D x 5.6"W x 1"H - **Sensor Type:** Ionization - **Style:** Precision Detection - **Unit Count:** 1 Count ## Images ![Hardwire Smoke Alarm | SMI100-AC, 9V Battery Backup - Image 1](https://m.media-amazon.com/images/I/61zYUADll+L.jpg) ## Available Options This product comes in different **Pattern, Size, Style** options. ## Customer Reviews ### ⭐⭐⭐⭐⭐ Good replacement alarm with simple install and battery backup *by on Reviewed in the United States 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. ### ⭐⭐⭐⭐⭐ Great Smoke Detectors *by on Reviewed in the United States July 5, 2026* I was able to replace 7 old Firex smoke detectors with these using an adapter. I had to buy the adapters separately on Amazon. These were very easy to replace. I just unscrewed the old screws (not all the way, just enough to take off old base plate). These base plates fit perfect on the existing screws, so just tighten then down. I attached the adapters to the existing wires and then to the new smoke detector, screwed the new detector onto base plate, pulled out battery pull tab, tested and good to go. I bought 12 detectors in June 2026 and they were all manufactured on May 15, 2026 so I had no issue with any being years old as others have said. All detectors tested good (loud alarm, interconnected with no issue) and have had no false alarms. Overall great purchase! ### ⭐⭐⭐⭐⭐ Easy Install and Setup *by on Reviewed in the United States 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. ## Frequently Bought Together - First Alert SMI100-AC, 9120B Replacement Hardwire Interconnect Smoke Alarm with Battery Backup, 1-Pack - First Alert SMICO100-AC Interconnect Hardwire Combination Smoke & Carbon Monoxide Alarm with Battery Backup, 1-Pack - First Alert 9120B Smoke Detector, Hardwired Alarm with Battery Backup, 6-Pack --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.co.za/products/609937867-hardwire-smoke-alarm-smi100-ac-9v-battery-backup](https://www.desertcart.co.za/products/609937867-hardwire-smoke-alarm-smi100-ac-9v-battery-backup) --- *Product available on Desertcart South Africa* *Store origin: ZA* *Last updated: 2026-08-15*