First Alert
First Alert SM300-AC
A
Ranked #1 in Smoke Detectors
822 LP on the
category ladder
what's LP?
Assumed baseline performance, likely reliable but lacks specific community praise.
Consolidated from 3 independent outlets
Where the cited sources landed, as we read them
- 3 positive sources
Pros & cons
- ✓ Widely available
- ✓ Standard smoke alarm
- ✓ Inexpensive combo
- ✓ Low failure rate
- ✓ Good firmware update support
The sources behind this ranking
We searched the web and YouTube for what has been published about this product, then read the articles, video transcripts and comments we found.
3 positive sources
B 
Business Insider Janelle Leeson · reviewer · Feb 2026 
Unitedsecurity Article 
Bhg Article
Business Insider Janelle Leeson · reviewer · Feb 2026 The First Alert SM300-AC is my top pick for its dependable dual sensors, battery backup, and whole-home interconnect capability. For those looking for smart features, I recommend the First Alert SC5 , a smoke and carbon monoxide detector that combines smartphone alerts with exceptionally broad interconnect compatibility, including with the discontinued Google Nest Protect system.Read U
Unitedsecurity Article The First Alert SM300-AC remains the gold standard for Canadian homeowners in 2026. Why? It features dual-sensor technology. Ionization sensors catch fast-flaming fires, while photoelectric sensors detect slow, smoldering fires. Having both in one unit significantly reduces false alarms from cooking or shower steam.Read B
Bhg Article If you want the broadest possible fire protection in a single alarm, the First Alert SM300-AC is a great option for homeowners. This hardwired detector combines ionization and photoelectric sensors so it can detect fast, flaming fires as well as slower, smoldering ones. It’s backed by a 10-year limited warranty.Read
Frequently asked questions
It ranks #1 of 10 on our smoke detectors tier list, in A tier. That placement draws on 3 independent outlets.
Ranked nearby in Smoke Detectors
A tier #2 Kidde Detect Smoke + Carbon Monoxide Alarm
B tier #3 First Alert SM500V Interconnected Battery-Operated Smoke Alarm with Voice Alerts
B tier #4 Kidde Smart Smoke + Carbon Monoxide Alarm
B tier #5 First Alert SMCO500V Interconnected Battery-Operated Combination Smoke & CO Alarm with Voice Alerts
C tier #6 First Alert SM500V Interconnected Battery-Operated Smoke Alarm
D tier #7 Kidde Smart Smoke + CO (Z-Wave)
D tier #8 1 of 6 research runs entered this as a product to avoid rather than a pick. First Alert SMCO210V Battery-Operated Combo
D tier #9 2 of 7 research runs entered this as a product to avoid rather than a pick. First Alert Z-Wave Smoke Detector
F tier #10 4 of 6 research runs entered this as a product to avoid rather than a pick.