Customer Ratings & Reviews

I had to replace my Nest hardwired smoke and carbon monoxide detectors after they were discontinued, and these First Alert detectors have been an excellent replacement. Retrofitting them to my existing Nest wiring was incredibly simple. First Alert even includes adapter harnesses, so you just disconnect the old Nest harness, plug in the new one, and you’re ready to go. The hardwired installation took me about five minutes per detector. Setting them up in the First Alert app was just as easy. Connecting them to my home’s Wi-Fi was quick and painless, and they also connected perfectly to my eero mesh network. Everything worked exactly as it should. I’ve had these installed for almost a year now, and they’ve performed flawlessly with no issues. The only feature I truly miss from the Nest Protect is the Pathlight feature. Nest would automatically illuminate a soft light when it detected motion at night, making it easy to safely walk down a dark hallway or find your way out of the house without turning on lights. I wish First Alert would add a similar motion-activated guidance light in a future model. It was a simple feature, but one I used almost every night. Other than that, these are outstanding detectors and an excellent replacement for the discontinued Nest Protect units. I would definitely recommend them.

Installation was a piece of cake. Was able to use pre-installed Nest Protect mounting hardware and wiring. Just needed to use the included adaptor wire to connect the device. The new devices are able to communicate with other pre-existing, non-expired Next Protects. I was also able to seamlessly connect the devices to Google Home. The only thing I do not like is that this product does not have the night light feature the Next Protect has. Overall I would recommend this product if you are replacing Nest Protects.

So far so good, set up was easy and quick, provides both sets of wire adapters such as if replacing Nest smoke detector or just another company smoke detector. Didn’t need to remove previous mount for the ceiling but it did come with its own also of course. Pretty clean and good design, oh and there’s 3 different locations for QR code, couple places to write down date of installation. What I wish they carried over is the path light that Nest smoke detector has. I’ve had it up for 11 days and does good test and sound.

I purchased three of these alarms because of the compatibility with Nest Protects and was very happy until a week ago. The initial setup was super easy and way better than the Nest setup. The app was nice and smooth however, two weeks into owning them two of them gave false alarms. Seven alerts within a 30 minute time frame. No dust in the house. No cooking or smoke going on. No steam or high humidity. From what I am able to find on the internet, the problem is not too common so maybe some other facter at play because its been a week and have not got other false alerts. Another odd thing was that the alerts came by push notification to my phone but when I opened on the app, it said no smoke or CO2 detected.

I needed to replace my hardwired Google Nest that was discontinued. This was a one to one replacement. Fits all existing hardware. Perfect fit. It took me 5 minutes to replace.

Got these smoke detectors to replace the nest protects since they are no longer making them. They are average at Best but they do the job. They have no where near the features the nest protect did but it works. They connect together we have a total of 6. My son burnt a grill cheese on the stove and the smoke set them off so we know they work. However the same night they went off again for a false alarm. So yes we did have one false alarm for no reason. Been okay since then. Wish they had a path light.

Works perfectly in our new construction home. I love the remote monitoring for when we aren’t there.

It is missing some functions, like the path light, but in general it is a good replacement for the original nest protects.

First Alert’s SC5 Hardwire Smart Smoke & Carbon Monoxide Alarm combines protection and tech in one convenient package. Smoke and carbon monoxide alarms are mandated by building codes depending on where you live for their potential lifesaving benefits. While we may have the best of intentions, monitoring them for their upkeep (i.e. maintenance, alerts, batteries etc.) can fall along the way. First Alert’s SC5 helps minimize this by connecting you to these devices and providing notifications as events occur. As packaged: • SC5 Hardwire Smart Smoke & Carbon Monoxide Alarm • Mounting plate • Mounting screws • Wire nuts • Power connector and adapter • Battery • Quick start guide • Installation & reference manuals • Safety brochure on carbon monoxide (CO) Numerous studies have proven the usefulness of smoke alarms. They dramatically reduce fatality rates when present and working. A 2024 study by the National Fire Protection Association estimated this reduction as nearly sixty percent. While they are beneficial it is also important to note that a nonfunctioning smoke alarm is as useful as having non at all. A device which is capable of delivering alerts about its functional status, events and equipped to be even tested remotely makes everyone’s life a whole lot safer in my opinion. The SC5 also detects carbon monoxide which compared to smoke is often discovered too late without a monitoring device. Compared to my previous smoke alarm, the SC5 has larger dimensions at 5.75 x 5.75 x 1.6 inches. The device has two LED indicators: a power LED to indicate connection to a power source and a centrally located halo LED for conveying visual notifications. Along with the sound, voice notifications are provided by the SC5 depending on the nature of the event. In my experience, I do not envision being spooked or startled by the voice in contrast to other devices I have previously experienced. Installation was straightforward for my setup. Swapping out a previous smoke alarm was literally plug and play. I did replace the mounting plate though. My smoke alarms are interconnected and as such I was able to interconnect the SC5. By having an interconnected system, the SC5 will sound the alarm when another smoke alarm has been triggered by smoke and vice-versa. For carbon monoxide, however, only the SC5 will sound when triggered. The other interconnected devices will only sound if they have the smart interconnected feature. As some homes may not have the interconnected feature, the power connector has this wire covered by default. It thus required cutting to make the strands available during the installation. Once powered, the device provides prompts to help with setting up the First Alert by Resideo app. It is available from the Apple App Store and Google Play. The SC5 can operate on either 2.4Ghz or 5Ghz frequency but as there is no hub provided, each unit will appear as a single device on your network. The app is intuitive and easy to use. It provides weather information (from the location input during setup) and an overview of activity and status of the SC5. Should additional devices be purchased and linked to the account, they would be displayed as well. Integration with Google Home for home automation is also available if needed. The device’s 3V battery is user-replaceable and the device will not operate without one. Like regular smoke alarms, the SC5 alerts when battery gets low. Alerts can be configured to provide an advance warning of about 2 weeks as the device also reaches the end of its useful life in about 10 years. This should provide the user ample opportunity to evaluate their options and not be caught out there without a functioning smoke and carbon monoxide alarm. During operation, the halo LED illuminates and flashes based on the status and the notification intended. Ater conducting a test, the current carbon monoxide level is provided. Depending on the levels detected, the frequency of alarm may be as short as 4 and 15 minutes (400 ppm) or as long as 60 and 240 minutes (70 ppm); these conservative thresholds should provide ample time before life is threatened when adhered to. Without a doubt, First Alert’s SC5 Hardwire Smart Smoke & Carbon Monoxide Alarm will save lives. While there are other smoke and carbon monoxide alarms, the SC5 tracks events /activities in one central location and also ensures the user is notified about maintenance issues when applicable. I am particular pleased with the interconnecting feature to existing smoke alarms that may not be as smart. My recommendation for a future update would be the addition of a hub to help reduce the device count on networks; this should help networks that may be close to capacity and thus not operate optimally. I wholly recommend First Alert’s SC5 Hardwire Smart Smoke & Carbon Monoxide Alarm and plan to add more to other locations.

The setup was easy and I love being able to get alerts or check the status when I'm away from home. Design I'm used to smoke detectors being circular. I don't have a problem with that, but I like the way this is square with rounded corners. I just think it looks cool. Practically, I like the very visible power light on the one side and the large center button that lights up in different colors when needed. The lights may not seem like a big deal but I've worked with other smoke/CO detectors that have a small light you need to look up in a small hole to see. It also has voice prompts during setup which are helpful and made setup easy. It takes a battery pack. You can't use a 9 volt or AA batteries or anything like that. Installation and Setup The installation was easy. This is the only WiFi enabled Smoke Detector I have but it's connected, by the orange wire, to my other smoke detectors. So if any go off when I'm not home, I'll still get a notification on my phone. When you pull out the tab that connects the battery and basically turns it on, it goes into setup. It asked a few questions and then asked if I was going to use it with the app or on WiFi (not required). Since I was I continued setup on the app. I installed the "First Alert by Resideo" app. I created an account, then it walked me through pairing with the smoke/CO detector and connecting it to WiFi. It also lets you name your house/building and the room the detector is in. Now I can easily go into the app from anywhere and see the current status. The detector checks in at least one time a day. I've included some pictures that show my old smoke detector that I replaced. I was able to use the same wiring and connection and even the same screws and screw holes. I did need to swap the mounting plate I had out with the new one. Features Once installed, there isn't really a lot to do. Again, to me to big benefit is that I can get notification when I'm away if any of the alarms in my house go off. And actually, the lights and voice prompts are provide better information than I've seen from other smoke detectors I've used. You can also test the smoke alarm by using a button in the app. The log in the app is nice too. It tracks things like when it lost power and when power is restored or if an alarm is triggered. If an alarm goes off it gives the option to dial 911 with one touch. It can also integrate with Alexa or Google Home. Summary If I was building a new house I would want them all to be like this! I think the design is more practical with more visible and versatile lighting as well as the voice prompts - and then the app. I've had problems in the past where a detector went off or chirped due to low battery or something and I didn't know which one caused it. There are usually, maybe always, ways to tell but I've found it's not always easy. With the detector itself, I feel like it would be easy but with the app, there would be no guesswork.

TLDR: Smart option for traditional smoke & CO2 Alarms. Compatible with Nest Protect PROS Compatible with Google Nest Intelligible Voice Alerts & Prompts Color Coordinated Light Ring for Alerts CONS Android Set-up a Mess Another 3rd Party Smart Alarm Player Interconnect Wire protector must be cut off SET-UP There is no other way to put it, Android set-up is a convoluted mess. So much so, that I was forced to use an iPad for device set-up. Word of advice, when initially trying to configure the device, DO NOT install the Resideo FrontEnd app when prompted. It will make the whole Android set-up process a train wreck. Strangely, the iOS app doesn't prompt you for, or require installation of the FrontEnd app, for the First Alert app to install and work correctly. Once I pulled out my trusty iPad, set-up was quick and easy, taking little to no time. The First Alert app is actually kinda slick once I got it working. It walks you through the entire set-up and configuration of the SC5 Alarm. Instructions are nearly fully comprehensive and thorough. The only thing in question, or I think could use better explanation, is the orange wire on the adapter for the interconnect function. First time installers will likely get confused with the orange interconnect wire mainly because the protective cover is not easily removable like the black and white wire covers. I've installed dozens of smoke alarms over the years and even I had to break out the printed directions to make sure the orange wire really needed to be stripped back and connected to my existing interconnect wires. Other than that, the app is easy and user-friendly. It took far longer to get the app set-up and configured with the Android issues than it did to install the SC5 Alarm. My hardwired Alarm came with an extremely nice mounting plate that is made to fit nearly any round or square mounting box. Multiple mounting configurations and extremely thoughtful rubber gaskets make for a premium feeling product. CONS Like I stated earlier, trying to initially set-up the device with Android is a mess. It doesn't work right and forces use of an iOS device to get it set-up and configured. At least it did for me. To be fair, once I got the device configured and uninstalled the FrontEnd app, the First Alert app has worked flawlessly since. However, if you read any of my reviews, I have little to no tolerance for apps and products that are not fully ironed out upon release. FINAL THOUGHTS I like having a smart, hard-wired, interconnected smoke/CO2 alarm. This is my first "smart" smoke detector and I am extremely pleased it is able to connect with my other 10 "dumb" smoke detectors. The peace-of-mind that comes with a "smart" connected smoke/CO2 detector is great. The app promptly sends a push notification if an issue is detected and will either "trip" the other detectors in my house to go off or if I manually test one of my dumb detectors, it will start my SC5. It is a seamless integration. The main concern with the First Alert SC5 is that it is yet another smart device in a market that is getting overly saturated. Partnering with Google Nest is a smart decision as users can opt to monitor the detector via the First Alert app or the Google Nest app. I think this is the one feature that will ensure it isn't left behind and becomes a little known, forgot about device in the market that is already being dominated by many competitors. RECOMMENDED

First Alert is a highly respected leader in connected security systems & smoke detectors, building a stellar reputation for over 60 years. First Alert introduced a Smart Smoke & Carbon Monoxide Detector that will replace the Google Nest Protect Smart Smoke + CO2 detector, which has been discontinued. I have a number of these Nest Protect detectors in my home; 2 have already crossed the 10-year life span & will no longer protect. Carbon Monoxide detectors are critical to alerting residents from odorless, colorless gas that can silently kill you, especially in homes with attached garages or fuel-burning appliances. Problem: the CO2 sensor only lasts about 10 years, after which the entire detector must be replaced. This First Alert detector mounts directly to my existing Nest bracket with a simple 1/4 turn clockwise rotation. An included optional adaptor plugs into the existing Nest cable to effortlessly reconnect to house wiring! The Nest app does not see the First Alert detector, so I installed the First Alert App. If you did not previously own the Nest detector, this First Alert detector is very easy to install & set up. A green LED shows power is applied & the detector is on guard. Battery backup is provided for peace of mind during power failure. This First Alert detector retains the same attractive square with rounded corner appearance as Nest Protect, that immediately distinguishes itself from all lesser detectors. CONCLUSION: This smart detector interconnects with all compatible alarms in my home, so all alarms sound on any alert. My favorite feature is how First Alert sends smoke & CO2 alerts to my phone. First Alert continues to be the security leader in innovation. This smart detector earns my highest recommendation.

This is First Alert’s flagship smoke/CO detector that’s meant to take over what Nest Protect started. While it does make it easy to switch from a Nest Protect with minimal effort and has a clean appearance, it’s priced the same as its spiritual predecessor while being noticeably cheapened across the board. Gone is the much-loved path light feature and in its place is a lower quality speaker and status LED array. Feature-wise, it’s fully capable and can interlink with other First Alert detectors, but it’s button and chassis feel much more in line with an average, cheap smoke detector than the durable quality that Nest pioneered …and that owners had praised for years. If it’s your first smart detector much of this may not matter as much to you, though you'll still be paying more for less. __ Design and Build Quality __ First with the good stuff. First Alert thankfully designed this model to utilize the existing mounting plate from the Nest Protect, so you don’t have to make new holes or adjustments in your ceiling to attach this one. (The new plate seems just as sturdy, but it appears to have fewer holes that are placed differently.) Overall, it’s also arguably more minimal and simple aesthetically. It has a very clean form that helps it disappear into the ceiling. But that’s where my praises end. The center button feels very cheap and somewhat hard to activate, while the speaker that's used to speak warnings, testing, and setup information in a female voice is also fairly low quality - though thankfully not ridiculously loud like other models. The status glow is dim and may be hard to see in brighter rooms and the green indication light is large and appears to stay on all the time in the wired model. Lastly, at this price it’s a shame to lose the ever-useful path light feature that was surprisingly helpful in dark hallways. Many people swore by it as a reason to spend this much. __ Setup and Daily Use __ Regardless of if this is your first smart smoke detector or not, it does most of the important stuff well. While the included paper instructions weren’t the most direct on where you should start, it’s easy to setup by starting with First Alert’s app. The app is basic, but works. It steps you through the process clearly and without much hassle. Connecting to the device, inputing a wifi password, giving it an associated room and name was all easy. I haven’t had any issues with keeping a connection so far. If you’re away when an alarm sounds, the app can send a push notification to alert you of the triggered detector. This alone is quite helpful if you’ve never had a smart detector before. Safety first. While I don’t love the price-to-quality ratio of this device, First Alert is a reliable brand and that’s still worth something. This detector also connects to the Google Home App just as the Protects did. Setup was simple, once I figured it out. Beyond the small label on the box, the instructions don’t seem to mention anything about it. You first start with First Alert’s app, which requires you to create an account with them, you’re then given the option to link this account to your Google Home account. In my experience, it was easy and worked right away, though the app did incorrectly state that an error had occurred during the link. In the wired model, a Nest-compatible adapter cable is also included in the box, allowing you easily connect to this new detector without having to mess with live wires and lock nuts. __ Summary __ With a minimal form and all of the primary smart safety features in tow, this should make for a good replacement for the Nest Protect line… on paper at least. In reality, Nest owners may feel the downgrade in speaker quality and lack of the path light feature. This would have been more forgivable if priced lower to compensate, but it’s not. I can’t help but feel taken advantage of - just to keep using another system I’ve enjoyed and invested in. If you’re new to smart detectors, you’ll still appreciate a simple setup process and the primary alerting features here. It also looks nice and you likely won’t be interacting with it directly all that often, so some of the downgrades in physical quality may not be felt in the same way. Just know that you’re likely paying a markup for comparably lesser product. *** Stuff I liked *** - Minimal appearance blends into ceilings well. - First Alert is a trustworthy brand, interns of reliably sensing. - Can use an existing Nest Protect mount. - Wired model comes with easy adaptor, connects to Nest’s cable. *** Stuff I didn’t like *** - Same high price but cheaper components than spiritual predecessor. - No Path Light feature. - Requires First Alert account for smart features.

I have existing First Alert OneLink CO/Smoke detectors throughout my home today, and am now adding the SC5 Smart alarm to the mix to improve the digital intelligence of my overall solution. Historically, the SC5 unit has had mixed reviews - with many complaining of False alerts - some people even rushing home when they received a notification on their mobile device! For me - I haven't had that experience yet, so I'm hoping that those false notifications have been rectified. I've had it installed for about a week now - and now false positives have been received. I'm happy to report that installation was a breeze - using the same hard-wired plugs as the OneLink devices really just meant switching out the hanger ring and popping this one up. The reason for 4 stars vs 5 is that during the configuration to the mobile app, it goes through a registration process that errored out on me. Once that happened, I couldn't get it installed as it said the device was already registered and wouldn't let me continue without contacting support. Interestingly enough, in timeframe it took me to get ahold of support, it showed up in the app and seemed to be working. That's the only problem I've seen thus far. With battery back-up built in, this device should work in case of a power outage and the batteries are also accessible which to me means replacement is a possibility if needed. Overall - it installed easily (with that one minor issue), looks good on the ceiling (and has a rubber seal on each side of the mounting bracket to prevent air leakage to the attic - see picture) and the app seems to work well (see picture).

Replacing my old smoke AND CO alarm with one First Alert SC5 Hardwired unit was surprisingly hassle-free. Guided by the First Alert App, the setup was straightforward and took just 15 minutes from start to finish. The instructions were clear, the app interface intuitive, and the pairing went smoothly. What sets the SC5 apart are its smart features. One standout is the ability to receive real-time alerts on my phone, even when I’m away. That level of connectivity is genuinely reassuring and adds a layer of protection traditional alarms just can’t match. It also links with Google Home and Nest Protect, making it a natural fit for anyone with a smart home setup. I especially like the spoken voice alerts during testing/alarm—clear, helpful, and far more user-friendly than just a series of beeps. My only suggestion is that the center light could double as a night light. Since I have the wired model, it’s powered continuously—and given its ideal placement, adding that function would enhance its utility even further. The only real downside is the price, which is a bit higher than standard models. Still, the smart features, fast setup, and added peace of mind make it worth considering for anyone upgrading their home safety system. Final Verdict: While a bit on the pricey side and the missing nightlight, the First Alert SC5 packs smart functionality, reliable performance, and easy integration—all in one sleek package. A solid investment in home safety.

It has been about 10 years since I last replaced my smoke detectors, so I was happy to try out the latest smoke and cabon monoxide detector by First Alert. My house is already set up with a hardwire connection and only took a few minutes to install. The initial setup, after downloading the First Alert app, went pretty smoothly. However, when I tried to integrate the detector into the Google Home app, I received an error. I tried a second time and received the same error, but noticed the detector was already within the Google Home app. I assumed the link failed error was an error in itself. The best feature this detector has, is the ability to receive alarm notifications on my phone. However, it is also nice to be able to test and silence the alerts remotely. It is worth noting this detector has a lit middle button during a notification, but stays off normally. Also, even though the alarm has a built-in speaker, you cannot use it to receive a broadcasted message or ask google questions. I would recommend this smoke and carbon monoxide detector since it is from a trusted name and is able to send alerts to my phone. However, I would like for First Alert to add more speaker functionality and an optional nightlight.

I purchased this as an alternative to the now-discontinued Google Nest Protect Smoke/CO Detectors. Installation was simple. You have to install into the First Alert App initially, then you can link that account to Google Home. It all appears to be in sync with my other Nest Smoke/CO detectors. One feature that Nest had that this does not, is the night light feature. When installing these in hallways, having that feature was really useful. Other than that, I would recommend them.

Sad to see the Nest Protects go but these new first alert smoke and carbon dioxide detectors work great. Setup was easy and the adapters make them plug and play. I really wish these units had the night path-light feature the Nest protects had.

One of my Nest detectors expired and, since they no longer make it, this was advertised as a direct replacement. Well, sort of, it works with the Google Nest app but not fully integrated. Has it's own First Alert app. Overall easy to install and does as advertised.

The First Alert Smoke/Carbon Monoxide Detector works is a great choice (probably the only!) if you want a smart home device that connects seamlessly to Google Home. Setup is straightforward and linking it to the Google Home app took just a few minutes. The app provides clear status updates and lets me check in on home from anywhere. The device seems well made and the test button makes it easy to run safety checks. With the First Alert app you can view the battery level, Wi-Fi and power status, and more. If you’re coming from a Nest Protect, like I am, you’ll love the fact that your existing ceiling mount and wiring can be used. The existing nest wiring harness connects to an included adapter and everything just works. This is a huge plus if you’re invested in the Google Home ecosystem like me. On the downside, the always-on green LED is annoying. There is no way to turn it off or dim it. Not great in a dark room at night. I also miss the presence sensing and path lighting of my previous unit, which was a helpful feature for late night trips through the house. While the First Alert is strong on safety and Google Home integration, it’s missing some of my favorite features that I’ve grown to love. Overall, I’m happy to have a solid, well made, replacement that fits right in to my Google home setup.