Each night when you turn out your lights, Nest Protect glows green once to let you know your batteries and sensors are working.

Nest Labs

Each night when you turn out your lights, Nest Protect glows green once to let you know your batteries and sensors are working.


My sister has a smoke-detector complex.

It started two summers ago when she opened a vacation home for the summer, only to encounter several beeping smoke detectors. The beeps didn’t stop until she shut off power to the house and replaced all of the detectors’ batteries. Then they started beeping again in the middle of the night.

Three months ago, in her own home, all of the smoke alarms went off at once in the middle of the night, and since there was no smoke or fire, she couldn’t figure out which smoke detector wasn’t working. To escape the screeching noise, she and her infant son hid out in the car while her husband took out all of the smoke-detectors’ batteries and disconnected them from the house’s hardwiring. She eventually replaced all of the smoke detectors, because it cost less than paying an electrician to come out and diagnose the problem.

If these stories sound familiar, you’re in good company.

Smoke detectors and all of their confusingly scary beeps are a part of our lives. Even people who haven’t had midnight scares like my sister’s wonder if their smoke detectors are actually working.

Enter Nest Protect, a smoke detector and carbon monoxide detector that talks to you, can be tested with ease, and gently confirms that it’s working each night. If you have more than one Nest Protect, they connect to one another to share notifications and alarms. And it sends you mobile and Web notifications about your home.

One big button instead of a tiny dot? Homeowners sigh with relief.

Nest Labs One big button instead of a tiny dot? Homeowners sigh with relief.

Nest Protect comes in white or black, and is beautifully designed, with a large center button and a handsome pattern across its surface, disguising sensors and batteries. The center button has a ring around it that glows red, yellow or green in different situations.

Yet, elegant design and peace of mind come at a steep price: Nest Protect costs $129, which is four or five times as much as an average smoke detector.

Nest Labs, the Silicon Valley-based company behind this innovative device, recently made news when Google bought it for $3.2 billion. Its first claim to fame was the $249 Nest Thermostat, which I reviewed in 2011. It’s another gadget for the home, and it studies and learns your house’s heating and cooling patterns, automatically adjusting temperatures over time so you don’t have to think about them.

I tested two Nest Protects in my home, one in the family room and one in the kitchen. I set the first one up in just a few minutes, but had a little more trouble connecting my second device to the first, and couldn’t find a solution on Nest.com. An engineer from Nest walked me through a manual fix, and said this problem was associated with my specific wireless router, though I use a standard mainstream router. He also said the company is working on writing a post for the Nest website that would describe this problem for others who might encounter it.

After my devices were set up, I ran manual tests on them by following instructions that were narrated by a warm voice that came from the Nest Protect. These included a countdown and a loud beep, with instructions on how the alarm can be turned off — by tapping a large button or using a waving gesture.

Waving your hand several times below the Nest Protect will hush its alarm.

Nest Labs Waving your hand several times below the Nest Protect will hush its alarm.

Lots of people avoid testing their smoke detectors for fear of never being able to stop the piercing beep sound, so this alone is a step in the right direction.

During setup, the Nest Protect encourages you to follow along on the Web or via an app on Apple, Android or Amazon mobile devices. In my iPhone app, I labeled each Nest Protect according to where it would be installed. This gives you more specific information when you receive mobile notifications, telling you what is happening in specific rooms of your house.

I used a smoke-detector testing tool called a Smoke Sabre to imitate a fake fire in my house. This is an aerosol can with a long, cone-shaped saber that sprays smoke at the detector to see if it really works.

Mine worked, setting off the alarm. But instead of a brainless, shrill beep, my Nest Protect glowed yellow, then red, and said, “Emergency: There’s smoke in the kitchen.” It then let out the traditional smoke-detector beep, while glowing red, until I tapped its center button to hush the alarm.

Protect will give a Heads-Up (more casual warning) or an Emergency alarm, depending on the level of smoke or carbon monoxide in the room. If either is at a critical level, the alarm won’t be able to be hushed until smoke levels drop.

After my fake-fire experiment, the Nest Protect that I tested glowed red for about 10 minutes. This lets someone who wasn’t in an area know that something happened, and tapping the device’s button tells them. Mine, for example, said, “Smoke cleared in the Kitchen.”

App notifications give people additional options on what do, like basic fire-safety instructions (stop, drop and roll) and calling 9-1-1, which is set up by default.

Nest Protect works with iOS, Android and Amazon apps.

Nest Labs Nest Protect works with iOS, Android and Amazon apps.

Interconnected Nest Protects all sound their alarms simultaneously, so you’ll know there’s a fire or carbon monoxide even if it’s not in the same room as you. But an alarm can only be hushed on the Protect in the room where the smoke or carbon monoxide was detected. Since the voice on Nest Protect announces this, you won’t have to hunt around the house for the right smoke detector, like my sister did.

In addition to working as smoke- and carbon-monoxide detectors, each Nest Protect has its own light sensor. When lights turn off in a room, the Protect glows green once to give you a reassuring sign that its sensors and batteries work. This is called Nightly Promise.

The device’s light sensor also comes in handy with Pathlight, a feature that senses movement and shines down a white light to help people see in a dark room. I found that this worked during a trip to the kitchen around 4 am. Pathlight is set to work, by default, in all rooms except those that you label as bedrooms, where you wouldn’t likely want a light turning on whenever you moved.

At its price, Nest Protect will be a luxury item for most people. But its interconnected system, notifications and soothing voice will make you more relaxed as you manage your home’s safety.


Yes, this is expensive, particularly because the Nest smoke detector "expires" after 7 years (per the user guide).  Yes, you are supposed to replace all of your smoke detectors after 7 years, but who really does this?  With Nest, the detector simply stops working after 7 years.  

Matt Mascari
Matt Mascari

The interconnect issue with other products is a deal breaker.  In MA, any house permitted after 1/1/2008 requires heat detectors that are interconnected to the existing smoke detection system.  Because of a design choice, the Nest Protect is incapable of meeting this requirement.

This is on top of the requirements for for houses permitted after August 27, 1997 that need 1 per level and 1 per bedroom that must all be interconnected.  The Nest Protect design choice to not interconnect with other detectors makes it illegal (or at least impossible to sell) unless you replace all the detectors with Nest Protects.  In a 2 bedroom, 2 story with basement house, that's at least 5 detectors, and it get's worse with every additional bedroom or separate living area.  Minimum switching cost $650.

Permitted between between 1975 and August 27, 1997, the count goes down, but it's still all interconnected requirement.


I see these for sale in local Home Depot's, and I'm betting people are going to be upset when they fail inspections while trying to sell houses.


I bought several Nest Thermostats and smoke detectors. I really like them. After a fire in a gas heater in our garage , that I luckily caught when going to my car one morning, I realized that not only did I not have a detector in garage( bad) but since the garage is separate from the house , if I were in the house I would never hear the alarm go off in the house. With the Nests all talking to each other if there is a fire in one room regardless if in house or garage( where I have my office and spend all day away from the house) I will be notified. 

After installing we had our first real test of the detectors. My husband was cooking and things got smokey. Before some obnoxious alarm the Nest quietly started to say there was smoke in the hallway. I was downstairs in the basement doing laundry and clearly heard the basement detector talking . I also got an immediate ping on my iphone in my pocket. I went upstairs and pushed the button on the alarm since I knew it wasn't a true fire. But the detector kept glowing red until the smoke diminished. Once all gone the detector told us the smoke was gone and all went back to normal. 

I also like the idea that when we are away I will get a notification on my phone when and if there is any smoke detected. I can then quickly call the fire department to check out. Yes, a fancy burglar alarm system probably does this too, but once installed the Nest will be cheaper than a monthly bill.

A few people commented that they didn't want to replace all the wired detectors they already have. I didn't replace every smoke detector but have enough Nests around that if there is a fire I think I will hear the new alarms go off and still hear the old ones. Mostly putting a Nest in the separate house and garage is the best for me.  Also replacing the stupid one near kitchen is helpful. Like many people we usually had it disengaged as it always went off when we cooked and created smoke.

My only worry is that now that Google has bought Nest, they will know all about my movements in my house. Kind of creepy. No place is safe.


I wanted to love the Nest Protect.  But when I read the reviews, I think there is a critical problem: the Nest cannot communicate with other smoke detectors via existing house wiring.

This means that anyone with a large house has to either swap all of the detectors at once, or else they will have a house where possibly a fire starts in the basement but the people in the bedrooms upstairs won't know.

If this is wrong, I would love to know because I want to buy them.  But this is what the reviews say, and I can find nothing in the literature to suggest otherwise.

Stuart Strand
Stuart Strand

@Matt Mascari My 1999 house has about 10 wiring interconnected smoke detectors. to maintain interconnection with Nest Protects I would have to spend more than $1000.  Not gonna happen.  I love my Nest Thermostat, but will hold off until Nest lets its Protect connect.

Pauly D
Pauly D

Thank you for highlighting this issue with supportive detail. Deal breaker for me as well. Too bad. I wanted to like it.


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