Google Nest Protect (Wired) Review: The Hardwired Smart Smoke and CO Alarm Done Right
Combined smoke and CO detection, spoken early warnings and phone alerts on mains power with battery backup, let down by cost and no wired interconnect with non-Nest alarms.
The hardwired Google Nest Protect is the version to get if you have mains-powered alarm wiring and do not want to think about batteries. It detects smoke and carbon monoxide, speaks an early warning that names the room before the loud alarm, sends alerts to your phone when you are away, and interconnects wirelessly so every unit sounds together. It runs on house power with a 3 AA battery backup, tests itself with a monthly report, adds a pathlight, and uses Steam Check to cut nuisance alarms, all set up easily through the Nest app and rated for about 10 years. The main downsides: it is expensive, it only interconnects with other Nest Protects (not your existing wired alarms), it is managed through the Nest app with no Alexa, HomeKit, SmartThings or Matter, and spoken room names come from a fixed list. For Nest/Google homes with wiring, it is excellent.
- Homes with hardwired alarm wiring
- Smoke and CO peace of mind
- Google / Nest households
- No-battery-maintenance buyers
Pros
- Hardwired power means no routine battery changes or 3am chirps
- Detects smoke and carbon monoxide, with a 10-year sensor life
- Spoken early warning that names the room, plus phone alerts when away
- Wireless interconnection so all units sound together (even with Wi-Fi off)
- Self-tests with a monthly report, pathlight night light and Steam Check
- Easy ~5-10 minute install; ties into a Nest thermostat to cut heat on CO
Cons
- Only interconnects with other Nest Protects, not existing wired alarms
- Expensive compared with standard detectors
- Managed via the Nest app; no Alexa, HomeKit, SmartThings or Matter
- Spoken room names limited to a fixed list (no custom voice labels)
- Pathlight can wake light sleepers (disable per room); 2.4GHz Wi-Fi only
- Fixed ~10-year life, and wiring involves 120V house power
Who is the Google Nest Protect (Wired) for?
This is the mains-powered version of Nest's smart smoke and carbon monoxide alarm, for homes that already have hardwired alarm wiring and want to skip routine battery changes. It runs on house power (120V) with a 3 AA backup for outages, uses a split-spectrum sensor for fast and smoldering fires plus a 10-year CO sensor, and connects over 2.4GHz Wi-Fi and Bluetooth. It speaks an early warning naming the affected room, sends phone alerts whether you are home or away, and interconnects wirelessly so all units sound together and identify the source. It adds an automatic pathlight, Steam Check to reduce false alarms, self-testing with a monthly email report, and a large silence button. It works with Google Home and Home Assistant (no Alexa, Apple HomeKit, SmartThings or Matter) and can tell a Nest thermostat to shut off heat if CO is detected. It best suits homes with existing alarm wiring, Google/Nest households, and anyone wanting combined smoke/CO protection with remote alerts and no battery upkeep.
What buyers love
Owners love not worrying about batteries: hardwiring means no 3am low-battery chirps, and the backup batteries last for years. Installation gets consistent praise as quick and simple (around five to ten minutes, like changing a fixture), with clear app guidance and a rotating mount that makes the square unit easy to level. The early spoken warning is a standout, letting people silence a cooking false alarm from the app or a gesture before the loud horn, and the room-naming voice (smoke detected in the kitchen) is called genuinely useful in an emergency. Phone alerts when away, wireless interconnection so all units sound together (which several note works even with Wi-Fi off, via a proprietary link), self-testing with a nightly green light and monthly report, the pathlight night light, Steam Check, and tying into a Nest thermostat to cut heat on CO are all praised. Many owners describe replacing failing old detectors with several Protects and call it the best smoke alarm they have used, with a few likening it to what Apple did for the phone.
What to know before you buy
The biggest gripe is that it only interconnects with other Nest Protects, not your existing wired alarms, so in a fully interconnected home you would have to replace every detector with a Protect to keep them all sounding together, which several owners find frustrating (and a little cynical) for a safety device. It is also expensive, with several feeling a fair price would be much lower. Spoken room names are limited to a fixed list, so custom labels like garage are shown in the app but not announced aloud. It is managed through the Nest app and works with Google Home and Home Assistant, but there is no Apple HomeKit, Alexa, SmartThings or Matter, which disappoints buyers in those ecosystems. Minor notes: the pathlight can wake light-sleeping children (you can disable it per room), the app does not always clearly indicate when it is on mains versus battery power, and it is 2.4GHz Wi-Fi only. As with any CO alarm, it has a fixed ~10-year life, and since wiring it involves 120V house power, confirm the circuit is off before installing.
Is the Google Nest Protect (Wired) worth it?
For homes with hardwired alarm wiring, yes: it delivers combined smoke and CO detection, early spoken warnings, phone alerts and self-testing with no battery maintenance, and it installs as easily as a standard detector. It is a clear upgrade from basic alarms and especially compelling in a Google/Nest home. Just accept the price, that it only interconnects with other Nest Protects (plan to replace a whole interconnected set if you want them linked), and that smart-home control is limited to Google and Home Assistant. If those fit, it is one of the best smart smoke and CO alarms you can buy; if you need Alexa/HomeKit or want to keep mixing in cheap wired detectors, weigh that first.
Frequently asked questions
How is the wired Nest Protect different from the battery version?
The wired model runs on house power (120V) with a 3 AA battery backup, so you avoid routine battery changes, while the battery version runs entirely on 6 AA batteries. Both have the same smoke and CO detection, app features, pathlight and Steam Check.
Can it interconnect with my existing wired smoke alarms?
No. It only interconnects with other Nest Protects, over a wireless link rather than the traditional wired interconnect. To keep a fully interconnected home linked, you would need to replace all the alarms with Protects, which is a common complaint.
Does it work without Wi-Fi?
Core alarm functions and unit-to-unit interconnection work without Wi-Fi (units sound together via a proprietary wireless link, and you can start a test with the on-device button). Wi-Fi is needed for phone alerts, remote testing and app features.
Which smart home platforms does it support?
It is managed through the Nest app and works with Google Home and Home Assistant, and can tell a Nest thermostat to shut off heat if it detects carbon monoxide. It does not support Amazon Alexa, Apple HomeKit, Samsung SmartThings or Matter.
Does it reduce false alarms from cooking and showers?
Yes. Steam Check uses a humidity sensor to tell steam from smoke, and the early spoken warning plus a large silence button (and app silencing) let you stop a cooking false alarm before the loud horn sounds.
