First Alert SMI105-AC Hardwire Smoke Alarm 10-Year Battery
- Power Source: Corded Electric
- Sensor Type: Ionization
- Alarm: Audible
- Product Style: Precision Detection
Last refreshed Sep 8, 2026 · Based on the Amazon listing and published specifications, not hands-on testing.
A solid hardwired replacement for an interconnected smoke alarm circuit, with sensing tuned to cut down on cooking-related false alarms.
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ASIN: B0CJLCXYY6Model: SMI105-ACCategory: Smoke Detectors & Fire Alarms
Overview
Hardwired smoke alarm from First Alert built for whole-home interconnect, with a 10-year sealed battery backup so it keeps working through a power outage without a battery swap.
Because it wires into household power, this alarm suits new construction or a retrofit where an electrician or confident DIYer ties into existing smoke alarm wiring. The 10-year backup battery is sealed, so nothing needs replacing for the alarm's service life once it's installed.
- Hardwired with 10-year battery backup
- Precision Detection cuts cooking nuisance alarms
- Interconnects with compatible alarms
- End-of-life warning built in
Who it's for
Homeowners replacing an existing hardwired smoke alarm circuit, especially where several alarms need to sound together. Not the right pick for anyone wanting a battery-only alarm with zero wiring.
Pros and cons
- Reduces false alarms from cooking smoke
- Interconnects so compatible alarms sound together
- 10-year sealed battery backup, no battery swaps
- Indicator light shows which alarm triggered
- Requires household wiring, not a stick-anywhere battery unit
- Interconnect only works with compatible First Alert alarms
Performance notes
Precision Detection sensing is built to tell a real fire signature apart from cooking smoke, the most common cause of nuisance alarms. Because the units interconnect, one alarm sensing smoke triggers every compatible alarm on the circuit, and an indicator light on each unit shows which one sounded first. An end-of-life warning signals when the alarm itself, not just the battery, needs replacing.
Specifications
| Brand | First Alert |
|---|---|
| Model | SMI105-AC |
| Dimensions & fit | |
| Item Weight | 0.7 pounds |
| Item Dimensions D X W X H | 5.5 × 2 × 5.5 inches |
| Power & efficiency | |
| Power Source | Corded Electric |
| Construction & materials | |
| Color | White |
| Included components | |
| Unit Count | 3 |
| Other details | |
| Sensor Type | Ionization |
| Alarm | Audible |
| Product Style | Precision Detection |
| Number Of Items | 3 |
| Mfr Part Number | SMI105-AC |
| Builtin Media | Easy Adapter Plug |
| Item Type Name | Smoke Alarm |
| Operating Humidity | 10-95% RH |
Frequently asked questions
Is this alarm battery powered or hardwired?
It hardwires into household power and carries a sealed 10-year battery only as backup.
Will it interconnect with my existing smoke alarms?
It interconnects with compatible First Alert alarms so they sound together, per the listing.
Does it reduce false alarms while cooking?
First Alert states its Precision Detection sensing is designed to reduce cooking nuisance alarms.