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Smoke & CO Detectors · Head to head

Google Nest Protect (Wired) vs Shelly Plus Smoke Alarm

Full Smart Smoke & CO Detectors comparison in 2026

Updated October 2026
Data from Amazon and official Google and Shelly sites.
2026 verdict
Full safety suite or smart home building block: the Google Nest Protect (Wired) wins this one on protection, adding carbon monoxide detection and house power to its smoke sensor.
Google Nest Protect (Wired)
Winner
Google Nest Protect (Wired)
$499.99
Buy on Amazon USACheck price
It also senses occupancy, motion, temperature, humidity and light, tests itself, lights a pathlight, uses Steam Check against steam false alarms and interconnects wirelessly with other Protects. The Shelly Plus Smoke Alarm answers on price, warranty and platforms: it is the more affordable of the two, carries a 3-year warranty against 2, and works with SmartThings as well as Google Home and Home Assistant, with automations the Nest does not offer. It is battery powered, rated for 5 years on a CR123A, and detects smoke only. Choose the Google Nest Protect (Wired) for smoke and CO on existing alarm wiring, and the Shelly Plus Smoke Alarm for an inexpensive Wi-Fi smoke sensor that plugs into Home Assistant, SmartThings or MQTT automations.
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FeatureGoogle Nest Protect (Wired)Shelly Plus Smoke AlarmWinner
Price$499.99€39.95Shelly Plus Smoke Alarm
Rating4.64.4Google Nest Protect (Wired)
Warranty2 years3 yearsShelly Plus Smoke Alarm
Connectivity2.4 GHz WiFi, Bluetooth, Other2.4 GHz WiFi, BluetoothGoogle Nest Protect (Wired)
IntegrationsGoogle Home, Home AssistantGoogle Home, Samsung SmartThings, Home AssistantShelly Plus Smoke Alarm
SensorsSmoke, CO, Occupancy, Temperature, Humidity, Ambient Light, MotionSmokeGoogle Nest Protect (Wired)
AlertsFire Alerts, CO Alerts, Low Battery AlertsFire Alerts, Low Battery AlertsGoogle Nest Protect (Wired)
Tests ItselfYESNOGoogle Nest Protect (Wired)
PathlightYESNOGoogle Nest Protect (Wired)
Steam CheckYESNOGoogle Nest Protect (Wired)
ScreenNONOTie
Built-in SirenYESYESTie

What the differences mean

Carbon monoxide

The Google Nest Protect (Wired) detects smoke and carbon monoxide. The Shelly Plus Smoke Alarm detects smoke only, so it needs a separate CO alarm beside it near gas appliances.

Power

The Google Nest Protect (Wired) runs on house alarm wiring with a 3 AA backup. The Shelly Plus Smoke Alarm runs on a CR123A rated for 5 years and mounts anywhere without wiring.

Platforms and automations

The Shelly Plus Smoke Alarm works with Google Home, SmartThings and Home Assistant and supports automations. The Google Nest Protect (Wired) covers Google Home and Home Assistant only. Neither works with Apple HomeKit or Matter.

Self-testing and false alarms

The Google Nest Protect (Wired) tests itself, adds a pathlight and uses Steam Check to ignore shower and cooking steam. The Shelly Plus Smoke Alarm has none of these, so it is tested by hand.

Warranty

Shelly covers its alarm for 3 years, Google covers the Nest Protect for 2.

Which one to buy if

Shelly

Shelly Plus Smoke Alarm

25% OFF
Prime exclusive deal
€39.95
€53.43
Buy on Amazon GermanyCheck price
  • + Price: €39.95
  • + Warranty: 3 years
  • + Integrations: Google Home, Samsung SmartThings, Home Assistant
  • - Rating: 4.4 vs 4.6
  • - Connectivity: 2.4 GHz WiFi, Bluetooth vs 2.4 GHz WiFi, Bluetooth, Other

What owners say

Owners of both value getting smoke alerts on the phone while away, and both describe a quick setup. Google Nest Protect (Wired) owners single out no battery chirps, the spoken early warning that names the room, monthly self-test reports and units that sound together even with Wi-Fi down; they complain that it only links with other Nest Protects, that it is expensive and that Alexa and HomeKit are missing. Shelly Plus Smoke Alarm owners, many running Home Assistant, MQTT or other Shelly gear, praise pairing over Wi-Fi in minutes with no hub, the long battery life and how easily it feeds automations. Their complaints are a short pairing window and, from a small minority, false alarms after months of use.

Price history compared

Every price change of both, in the same store, so the gap between the two lines is what one costs more than the other.

  • Google Nest Protect (Wired)
  • Shelly Plus Smoke Alarm

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Frequently Asked Questions

Does Shelly make a carbon monoxide detector?

The Shelly Plus Smoke Alarm detects smoke only; it has no CO sensor and raises no CO alerts. If you want smoke and carbon monoxide in one unit, the Google Nest Protect (Wired) detects both.

Which is better: Google Nest Protect (Wired) or Shelly Plus Smoke Alarm?

The Google Nest Protect (Wired), for its smoke and CO detection, house power, self-testing, pathlight and Steam Check. The Shelly Plus Smoke Alarm is the better buy for a lower-cost Wi-Fi smoke sensor that works with SmartThings and Home Assistant automations.

Which works with Alexa?

Neither does: Alexa has no device type for smoke alarms outside Matter, and neither alarm is a Matter device. The Shelly Plus Smoke Alarm works with Google Home, SmartThings and Home Assistant, and the Google Nest Protect (Wired) works with Google Home and Home Assistant.

Does the Shelly Plus Smoke Alarm need wiring or a hub?

Neither. The Shelly Plus Smoke Alarm runs on a CR123A battery rated for 5 years and connects to 2.4 GHz Wi-Fi directly. The Google Nest Protect (Wired) needs an existing alarm circuit for power.

Who should buy the Google Nest Protect (Wired)?

Homes with hardwired alarm wiring that want smoke and CO protection, spoken room-by-room warnings and Google Home support without battery upkeep. The Google Nest Protect (Wired) costs more and only interconnects with other Nest Protects.

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