COMPARISON: First Alert One Link Wi-Fi Smoke and Carbon Monoxide Detector versus Nest Protect 2nd Gen Smoke + Carbon Monoxide Alarm

When the Nest Protect 2nd generation device was revealed in the summer of 2015 it was improving upon an already great device.  With no real competition to speak of I didn’t bother taking photos of my purchase, because there wasn’t really anything to compare it to for blog comparison purposes.  But now that the HomeKit-enabled First Alert DC10-500 One Link Wi-Fi Smoke and Carbon Monoxide Detector has arrived, let’s see how it stacks up against the Nest Protect 2nd Gen Smoke and Carbon Monoxide Alarm.

Readers of my blog know I don’t typically just do reviews.  With so many options on the market these days I tend to prefer to compare multiple items, and provide my unbiased opinion. All of the items I test are purchased by me, with no freebies or handouts.  This helps me preserve an open mind when testing and comparing devices.

This review is no different.  Although smoke alarms/detectors don’t have a lot of thing to test, I still wanted to give my readers a chance to read first-hand-details of the first smoke detector to be released with HomeKit capabilities.  And given that the gold-standard for WiFi smoke alarms has been the Nest Protect for some time, this should be quite an interesting shoot-out!


Photo Gallery – First Alert / One Link

Photo Gallery – Nest Protect

Getting Started

I’m going to apologize ahead of time, as I don’t really have any photos of the Nest Protect during setup or installation.  If you want to know more about how the install process looks, Nest’s web site has some great videos and information both HERE and HERE, so please check those out.

In both cases the setup is an extremely easy process.  Physically mounting the Nest Protect requires using the four self-tapping screws.  These are nice as they avoid needing to do any drilling.  You simply screw the base to the wall/ceiling surface, and you’re done.  In contrast, the First Alert / One Link required first drilling two 3/16″ diameter holes in my ceiling.  While drilling two holes is hardly a complex task, this does require additional tools that some folks may not have.

Software setup was a cinch in both cases, with neither having any sort of distinct advantage.  One key difference of the software setup is that the First Alert / One Link will also include creating your HomeKit home, if you do not already have one setup.  In my case my Home & Work locations already existed, so I simply needed to tell the device in what room the new device was being placed.

You can indeed have multiple locations with the Nest Protect, too, but as their device is not HomeKit capable this will have no bearing on voice commands, which we’ll talk about shortly.  In the case of both devices you have the option of performing a voice & sound test as you complete setup.

Hardware & Software Differences

Each of these devices run on batteries, but their approach is quite different.  With the Nest Protect you’re supposed to achieve “several years” of battery life (in some corners of the web I found 5-years listed as an expected life span).  Approximately 6-months before the batteries go south you should receive a warning, at which point there are six AA batteries that you can replace yourself quite easily.  Based on this the cost of ownership is relatively low, as AA-batteries remain fairly inexpensive.

With the First Alert / One Link unit you are supposed to be able to achieve a claimed 10-years of service from the battery within the unit.  But interestingly enough the battery is not serviceable.  Their attitude is that the unit will need replaced after 10-years anyhow (old age, old technology), and the battery need not survive beyond then.

Both units have internal hardware/sensors which are only rated for having a 10-years life-span.  I suppose this means the Nest needing a battery replacement at least once is a short-coming.  However, the cost of batteries is far less than the cost of a new unit.  Which means that should the First Alert need replaced prior to that 10-year period, this could increase the overall cost of ownership.  Having replaceable batteries in the Nest gives it a leg up, in my mind.

Both devices offered a wired version, should you be mounting the smoke alarm near power and/or replacing an existing hard-wired device.  Since that was not the case for my home my testing includes only the wireless options, which are the most common anyhow.

(24-November-2015) – UPDATE:  After becoming aware of this artice, Tom Russo, vice president of marketing for Jarden Safety & Security, maker of First Alert-branded products, reached out to me with some additional information regarding the 10-year life span on these devices.  According to First Alert, “the 10-year sealed battery helps prevent the dangerous but, unfortunately, all too common scenario of homeowners deliberately deactivating their alarm by removing the batteries – or simply forgetting to replace them. According to the National Fire Protection Association (NFPA), three out of five home fire deaths result from fires in properties without working smoke alarms – often due to missing alarm batteries. Plus, there’s money to be saved by not needing to replace batteries every six months! Both the alarm and the battery are designed to last 10 years.”  Hope this provides clarity for those wondering about this detail.

As you’ll see in the above photo galleries, the Nest Protect has a considerably bit more weight than the First Alert / One Link at around 125% the heft.  The Nest also feels considerably more dense, as it not only weights more, but is slightly smaller in size.  Side-by-side you’ll see how I mounted them.  Visually speaking the Nest is definitely the prettier of the two devices, but I wouldn’t call either ugly.

Each device has a ring of LEDs that illuminate different colors, indicating various alarms, states of syncing, and other matters.  I found the brightness of the Nest’s LED slightly brighter.  With the First Alert / One Link you only get a night-light feature with the wired version, and not in the wireless device I tested here.  As for the Nest Protect, you do get the “pathway light” feature even in their wireless unit.  Of course this will diminish battery life is used excessively, so beware.

As you dig through the two photo galleries you’ll see a lot more granular control of the Nest Protect.  It has more settings, more features, and more options.  From things like steam control, to the ability to tie in with their Nest Cam cameras, it definitely has a few more things going for it.  But as the One Link ecosystem grows, as well as the HomeKit platform, this variance may slim slightly.

Sound & Alarms Compared

Both devices are loud!  But there is a distinct difference in the way they sound, and in the quality of their voices when speaking.  Each device has a unique sound for smoke versus carbon detection, which you can hear during testing, or when an event occurs.  I did test smoke with each device, but had no real way (or desire) to test carbon monoxide.

In both cases each device will announce where it is located, when calling of the alarm. This is particularly nice if you have multiple locations and sensors, and want to hear from afar where the trouble is originating.  However, my wife and I both noted that the First Alert / One Link voice was rather hard to understand, perhaps because it was deeper and more “crunchy” sounding..  On the other hand, the Nest Protect voice was easy to understand each and every single word.  But where the First Alert voice could be heard, though not understood, upstairs– the Nest’s voice wasn’t audible when trying to hear it from a whole floor away.

With regards to the actual noises, the tones of the First Alert / One Link are a bit more guttural, with my wife describing it as sound more like a “buzzer” and less like the “beep” sounds of the Nest.  The One Link emits a deeper tone for both alarms which isn’t quite as loud upstairs (bedroom) (the device is mounted downstairs), though we’re confident either one would wake us up from a sleep.  We discovered that the higher pitched Nest Protect seemed slightly better at the intended purpose, since it was marginally easier to hear at a distance.  So both work, but the Nest’s higher pitch was perhaps a slight bit better for distance.  Even if you can’t hear the voice of the Nest from a distance.

During my testing where I invoked a smoke alarm (thanks to blowing out a candle nearby the devices), there were some key differences once again.  In the case of the First Alert / One Link their device relies on Bluetooth, switching on the WiFi only when needing to alert you of an alarm via their cloud service.  This did create some latency of receiving the warning on your phone almost 60-seconds after the local alert had started.  However, our testing found that the Nest Protect took anywhere from 30 to 45 seconds, so I’d hardly pick one over the other here.  And really, the local audio alerts typically matter more than the remote alerts.

In the next section I’ll explain another difference of how they worked, during alarms, as they integrate with other devices.  Oh and one other feature that the Nest Protect has that I like is the yellow flashing pre-warning, letting you know smoke is building before the alarm goes off, great for detectors that are placed near cooking areas or similar.

Siri versus Nest

Beyond both of these devices being WiFi smoke and CO detector alarms, they both bring unique integrations to the table.  With the Nest Protect you get placed into one of the best ecosystems on the market today.  Not only can their device integrate with their own family of hardware, you also get to play with other devices that Work with Nest.  And you can also integrate nicely with IFTTT for other features, too!

In our home, for example, we have both Lutron Caseta smart lighting, as well as some Philips Hue smart bulbs.  If your Nest Protect detects an alarm, it can automatically start recording on your Nest Cam cameras, and turn on your Lutron/Philips lights to help you see your way out of your home.  These types of features make the Nest hardware a great choice.  And they are always adding more devices to their already long list of “Works with Nest” hardware.  During our testing we found that the Lutron lights would come on within 20-30 seconds after the alarm audio starts, which was very impressive!

On the other hand the First Alert / One Link is jumping on-board to a new, but still budding platform from Apple.  The HomeKit platform is one I really do like, and actually just published a HUGE blog post about it here.  In the photo gallery you can see me querying the smoke detector to get information from it, though my questions were never during an alarm.

In addition, using HomeKit allows the same sort of “automatic lights on” integration, but it does take a bit more effort.  You not only need to make sure the lights you have are HomeKit compatible (instead of “Nest compatible”), but you’ll need to create a scene that is what you want to occur in an emergency, and then create the trigger.  And right now setting all this up required my acquiring a $15 Home iOS app, since Apple still hasn’t come out with anything on their own.

During our testing of the First Alert / One Link, when we set off the smoke alarm manually, we found hit-or-miss results with getting the lights to turn on.  I turned my phone’s WiFi/Bluetooth off, and set off the alarm.  This meant I was working exclusively in LTE.  Though the lights did eventually turn on, it took over two minutes before the lights came on, after the audible alerts had begun.  And in another test the lights never came on.  This pales in comparison of the Nest Protect, which pushed my Lutron Caseta switches to turn on extremely swiftly, and 100% perfectly during every test I conducted.

As for the Siri integration, being able to ask your smoke detector for a current status seems a bit trivial to me, but I guess it is a cool feature.  But more important is that the devices in your home work together nicely.  When two or more things start to mesh, and yield results of automation, that is when we truly achieve greatness in home automation.  So in both cases I was able to have lights turn on, or a thermostat turn itself off, and in truth I was able to mimic almost all of the features the Nest offers with my One Link, but it clearly was a bit more involved of a process wth the First Alert, and less reliable.  The simplicity and reliability of the Nest makes it a clear winner for now in this section.


If you don’t already have a bunch of smart home hardware, you’ll have a choice to make if you are thinking about buying a smart WiFi smoke & CO detector alarm.  Both are great devices, similarly priced, with nearly identical features.  There are key differences as discussed above, that do set them apart from each other.  While I’d be hard pressed to say one clearly was better than the other as a basic alarm/detector, the “smart” features tended to work more reliably with the Nest.

For most users, I think the Nest Protect 2nd Gen Smoke and Carbon Monoxide Alarm is the better buy.  Right now it has the bigger ecosystem, more integrations, crisper noise/voice, cleaner looks, easier to use app, more reliable integrations with other devices/apps, and a great support team and company to back it up.  And as you expand your home you’ll enjoy having bought into their platform.

However, as the Apple HomeKit platform becomes bigger and bigger, as I talked about in my other recent blog post, I think there will be something to be said about having a device that works with Apple.  If you’re looking to build a new smart home, and HomeKit is your desired platform, you now have an excellent option that is worth your money with the First Alert DC10-500 One Link Wi-Fi Smoke and Carbon Monoxide Detector.  I just hope they can add a bit more reliability to this device in the future.

Thanks for reading!


  1. someone please correct me if I’m wrong, but, does Nest not charge a monthly fee, to be able to do anything with the systems outside your house?

    • Nest offers their “Nest Aware” service, which is for cameras only. Even if you don’t have this service, but you have a Nest Protect, then you still get free video recording during smoke/CO alarm events. And you still get remote access to your cameras, and your detectors. AND… you still get third party integrations.

      I currently am NOT a Nest Aware subscriber. I do NOT pay anything to Nest. Because I am not paying, I don’t get any recordings of my video. I get alerts, but no recordings. No history.

      However, during my smoke alarm testing, I received emails showing clips that WERE recorded, for free. And my house lights (Lutron) all turned on automatically, thanks to Nest integrations.

      Neither of the devices tested here require a monthly fee. The only case where a fee would be warranted is if you wanted Nest camera recording, but that isn’t related to this article.

  2. Thanks for the comparison Ari! There’s a Nest hardwire unit in the pile of presents (with the Wink hub and Lutron switches) for when my wife gets back from her trip…. somebody owes you some money…

  3. Would mixing next and home kit work? I like the nest system better but am likely to go with home kit for most of the house. Lighting is the main feature I would think is useful with the alarm. Couldn’t the lutron lights be set up to work with home kit and also with nest? I guess this may not be a good idea even if it is possible since it is likely to cause more bugs in a bug prone setup but I was wondering if this is even possible.

    • Yes. Not only is this possible but during my testing this is exactly what I did. So if the Nest Protect sensed smoke/fire it links direct to Lutron and sets lights. As for the First Alert, it offers the same features via HomeKit though takes a bit more initial setup to make happen. Though a fragmented system isn’t always ideal, in this instance it can work just fine.

  4. I was hoping to find an answer to the pairing of other devices. I can’t afford a nest or one link in every location. I know the one link pairs with other first aler alarms. Does the nest?

    • I wasn’t aware that either of them had this ability (to link to other non-smart devices). So this is a question you’d want to contact the manufacturer to find out, since I’ve never heard of such a thing until just now.

  5. Thanks for this write up. Do you know of any improvements in the First Alert kits- since I’m asking two years since this was first written? I’d like to get our house set up and we are IOS everything (except for my husbands computer).

    • I was having connectivity issues with the First Alert over time– it wouldn’t be found by HomeKit or my iPhone, etc. So I eventually abandoned their device and went with only Nest Protect devices.

      Since the Nest still works with Lutron/Hue, it still integrates with my lighting. So in my case it was not a big deal to switch away from the First Alert.

      That said, I apologize, I don’t have any further testing data more recently on this unit. I’d hope they have made firmware updates and improvements, but alas, I’m not entirely sure. If you do end up getting some do let us know how it works out for you!

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