Google Nest Protect (Wired) vs Shelly Plus Smoke Alarm

The Google Nest Protect (Wired) is the better overall safety device because it detects both smoke and carbon monoxide, adds a deep sensor suite, tests itself and delivers spoken early warnings, plus it carries a higher owner rating. The Shelly Plus Smoke Alarm is smoke-only but wins on price, warranty length and broader smart home integration.

Coverage versus connectivity. The Google Nest Protect (Wired) is a combined smoke-and-CO alarm with self-test and a pathlight, while the Shelly Plus Smoke Alarm detects smoke only but integrates with Google Home, Alexa, SmartThings and Home Assistant and supports automations.

The Shelly Plus Smoke Alarm reaches more: Google Home, Amazon Alexa, Samsung SmartThings and Home Assistant, plus automations. The Google Nest Protect (Wired) works only with Google Home and Home Assistant, so the Shelly is the more flexible choice for a mixed-platform or automation-heavy setup.

The Shelly Plus Smoke Alarm carries a 3-year warranty and a CR123A cell rated for about 5 years, while the Google Nest Protect (Wired) has a 2-year warranty and runs on mains power with a 3 AA backup. The Shelly leads on warranty length and battery rating.

Buy the Google Nest Protect (Wired) if you have hardwired alarm wiring and want one device covering both smoke and carbon monoxide, with spoken early warnings, phone alerts, self-testing and a pathlight, ideally in a Google or Nest home.

Buy the Shelly Plus Smoke Alarm if you want an affordable, automation-friendly WiFi smoke sensor with a long battery rating and broad support for Google Home, Alexa, SmartThings and Home Assistant, and you can add a separate CO detector for carbon monoxide.