Head-to-head · Best Smart Smoke Detectors

First Alert SC5 Hardwire Smart Smoke and CO Alarm vs X-Sense XS01-M Interconnected Smart Smoke Alarm (FS31 kit)

Which is the better buy? Side-by-side on rating, price, strengths, and watch-outs — with the published ratings we averaged to get there.

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The short answer

X-Sense XS01-M Interconnected Smart Smoke Alarm (FS31 kit) comes out ahead by a narrow margin (4.1 vs 4.0). X-Sense XS01-M Interconnected Smart Smoke Alarm (FS31 kit) is best for: Homes without interconnect wiring that want every smoke alarm to sound together and send phone alerts, and that already have separate carbon monoxide coverage. Read the strengths below before deciding.

Ranked #3 in Best Smart Smoke Detectors

First Alert SC5 Hardwire Smart Smoke and CO Alarm

4.0

1 sourceall derived$128.89as of Oct 6

The First Alert SC5 is engineered as a direct drop-in replacement for the discontinued Google Nest Protect, utilizing an included wiring adapter to fit existing ceiling mounts without requiring new electrical work. smarthomecompared found that its dual photoelectric and electrochemical sensors effectively distinguish between hazards like grease fires and carbon monoxide, while PureReviews noted that loud voice alerts specify both the danger type and device location for clear identification during emergencies. However, the unit lacks motion-activated pathway lighting and automated self-testing, forcing users to manually verify operation via a button press rather than relying on daily diagnostics. Because it works exclusively with the Google Home app and offers no Alexa or Apple HomeKit support, this alarm fits only households already invested in that ecosystem who prioritize easy installation over smart home versatility.

Strengths

— Designed as a drop-in replacement for discontinued Google Nest Protect, fitting existing ceiling mounts with included wiring adapter
— Features loud built-in siren with voice alerts that specify the danger type and device location
— Combines photoelectric smoke sensor and electrochemical CO sensor in one unit to reduce nuisance alarms

Watch-outs

— Lacks motion-activated pathway night light found on the Nest Protect it replaces
— Works exclusively with Google Home app, offering no Alexa, Apple HomeKit, or Matter support
— Missing self-testing automation feature, requiring manual button presses to verify operation

$128.89 · Check Price on Amazon Full review →

Higher ratedRanked #2 in Best Smart Smoke Detectors

X-Sense XS01-M Interconnected Smart Smoke Alarm (FS31 kit)

4.1

1 source$30as of Oct 10

The X-Sense FS31 kit is three battery-powered XS01-M smoke alarms linked by radio to a small Wi-Fi base station that relays alerts to the X-Sense app. PCWorld rated it 4 out of 5: in its testing a test alarm set off all three units from the far corners of a house, simulated smoke triggered them quickly, and push and email notifications arrived in seconds. PCWorld's criticisms are that the alarms do not detect carbon monoxide, the base station has no battery backup so phone alerts stop in a power outage, and one alarm dropped offline during testing and would not reconnect.

Strengths

— In PCWorld's test all three alarms sounded together from the far corners of a house, through walls and floors
— Alerted quickly to simulated smoke, with push and email notifications sent in seconds, per PCWorld
— Alarms kept triggering one another with the base station unplugged in PCWorld's testing

Watch-outs

— Does not detect carbon monoxide
— Base station has no battery backup, so a power outage stops push notifications, per PCWorld
— Base station connects to 2.4GHz Wi-Fi only

$30 · Buy at x-sense.com Full review →

Derived means the reviewer published no score, so one was inferred from their written verdict. Everything else is a number the publisher printed. How we rank.

How they stack up

First Alert SC5 Hardwire Smart Smoke and CO Alarm

The SC5 is hardwired with a lithium backup, like the Kidde Ring-Enabled detector, which uses AA backup batteries; the X-Sense SC07 runs on a CR123A lithium battery instead. The SC5 is controlled through the Google Home app, where the Kidde reports through the Ring app.

X-Sense XS01-M Interconnected Smart Smoke Alarm (FS31 kit)

Unlike the X-Sense SC07, the Kidde Ring-Enabled detector and the First Alert SC5 on this page, which all combine smoke and carbon monoxide detection, PCWorld notes the XS01-M alarms detect smoke only. They run on batteries, where the Kidde and First Alert SC5 are hardwired, and they depend on a plugged-in base station for app alerts.

Specs side-by-side

Spec	First Alert SC5 Hardwire Smart Smoke and CO Alarm	X-Sense XS01-M Interconnected Smart Smoke Alarm (FS31 kit)
Power Source	Hardwired with Lithium backup	Alarms: replaceable 3V lithium cell; base station: USB-C, no battery backup
Compatible Ecosystems	Google Home app only	—
Lifespan	10 years	—
Sensor Type	Photoelectric smoke, Electrochemical CO	—
Dimensions	5.75"D x 1.6"W x 5.75"H	—
Detection Type	Smoke and Carbon Monoxide	Smoke only
Connectivity	First Alert App / Google Home	Wi-Fi (2.4GHz only) via base station; X-Sense app
Alarm Volume	85dB at 10 feet	—
Kit contents	—	Base station plus 3 XS01-M smoke alarms (X-Sense model FS31)
Battery Life	—	5 years claimed for the preinstalled batteries
Alarm Lifespan	—	10 years
Interconnect	—	915MHz radio between alarms, up to 24 alarms per network
Base Station Size	—	3.5 in square

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