Best wireless interconnected smoke and carbon monoxide detectors

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Placing smoke detectors throughout your home is a must, but internet-connected smart smoke detectors take fire safety a step further with advanced monitoring features and direct alerts to your smartphone anywhere you are.

To learn more about these devices, we spoke with an electrician experienced in installing smoke detectors and other smart home products. "We tell customers it's great to have smoke detectors hardwired; that's the best," says Justin Landeen, vice president of business development and smart home installation manager for Penco Electric.

With installation in mind, we researched and tested available options based on other essential features, including sensors, app control, and smart assistant compatibility. We consider the Google Nest Protect smoke and carbon monoxide (CO) alarm the top choice for most buyers because of its reliability, self-checking functions, and smart features.

Here are our picks for the best smart smoke detectors.

What We Like

• Smart device connectivity

• Alerts you before alarm sounds

• Auto-testing and battery monitoring

• Motion-sensor night light

What We Don't Like

• Expensive

• Potential for Google to collect homeowner data

The Google Nest Protect is a pioneering smart smoke detector that, in its second iteration, remains at the top of the market. Despite the high price tag, our tester gave it a full 5 out of 5 stars for its combination of quality and user-friendliness. As a testament to the easy setup process, our reviewer was able to install two battery-powered Nest Protect units (hardwired installation is an option as well) in the span of 20 minutes. The devices quickly connected to the Wi-Fi network and the Nest app, where heads-up smoke alerts come through and can be dismissed before the full, very loud alarm goes off.

The Nest Protect even features advanced technology in terms of smoke detection, combining the strengths of photoelectric and ionization sensors into a split-spectrum sensor that better detects both smoldering and flaming fires, in addition to greatly reducing false alarms. Our tester reported that this alarm "is smart enough to distinguish real smoke from shower steam or minor cooking smoke." When compared with two other models he tested, the Nest Protect was the only device that didn't sound as a result of cooking—despite being "mounted right next to one of the offending alarms." The built-in carbon monoxide (CO) detector is similarly accurate and lasts 10 years. The device also self-checks all its sensors and battery levels 400 times a day, with speaker tests once a month.

Besides notifications on the app, the Nest Protect itself issues voice prompts that describe what's happening (and where), with the ring of light around the center button changing colors. The ring's glow can be activated via a motion sensor in the dark, serving as a night light that became a surprisingly valuable bonus feature in our reviewer's home.

Power Source: Hardwired or battery | Compatibility: Wi-Fi, Google Home | Sensors: Split-spectrum | Extras: Carbon monoxide monitoring, battery self-check, voice prompts, motion-sensor light

What We Like

• Simple installation and setup

• Compact size

• Affordably priced

What We Don't Like

• No carbon monoxide monitoring

• No hardwired option

• No voice features

Any smoke detector with smart features will understandably cost more than a standard alarm, but with the XS03-WX Wi-Fi Smoke Detector from X-Sense, the price hike is much less dramatic. It represents an affordable way to connect your smoke detector to the internet and control it remotely through a mobile app. This model includes the ability to receive real-time alerts, silence false alarms, and check the status of the replaceable lithium battery.

With no option for wiring the XS03-WX directly to your electrical system, installing the device with the included mounting screws or adhesive is straightforward and quick. It fits well into just about any home setup, thanks to a compact circular shape at roughly 3 inches across and 2 inches deep. The smoke sensor is photoelectric, responding faster to smoldering fires than flaming ones, and there's no carbon monoxide sensor (in this or any other X-Sense Wi-Fi models). For this reason, having separate ionization detectors and CO detectors is recommended for full coverage.

Power Source: Replaceable CR123A lithium battery | Compatibility: Wi-Fi, X-Sense app | Sensors: Photoelectric | Extras: Battery self-check

What We Like

• Reliable smoke and CO detection

• Voice commands and alerts

• Can interconnect with other alarms

What We Don't Like

• No Apple HomeKit support

• Can't use Smart Hush or test commands via voice

Kidde, a leading manufacturer of fire safety products, took some time before entering the smart smoke detector arena, but its Smoke and Carbon Monoxide Alarm with Smart Features is well worth considering if you're looking for a device with double-duty detection. Beyond the established brand, as a UL-listed product tested and certified for reliable home use, you can feel confident in its performance with CO and fire hazards.

The Kidde Smoke and Carbon Monoxide Alarm requires hardwiring to your home's electrical system, with a 10-year lithium battery as a backup. Connecting your Wi-Fi network unlocks its smart capabilities, including remote access, notifications, and a Smart Hush feature for false alarms. You can also issue commands through the Amazon Alexa or Google Assistant voice assistants (though it's incompatible with Apple HomeKit), and the device itself provides voice alerts in addition to its 85-decibel alarm. Plus, if you happen to have other Kidde alarms that are hardwired and interconnected to this one, they all activate and send phone alerts when any of them go off.

Power Source: Hardwired; lithium battery backup | Compatibility: Wi-Fi, Amazon Alexa, Google Home | Sensors: Photoelectric | Extras: Carbon monoxide monitoring, voice prompts

What We Like

• Built-in Alexa smart speaker

• Reliable smoke and CO detection

• Apple HomeKit and AirPlay support

What We Don't Like

• Expensive

• No battery or sensor self-checks

Although safety and peace of mind are top priorities for any smoke detector, the First Alert Onelink Safe & Sound adds a unique element of convenience and entertainment through a built-in Amazon Alexa smart speaker. You can ask Alexa to control other smart gadgets, tell you the news, read audiobooks, or play music straight from this smoke detector's strong, premium speakers. The Safe & Sound also supports Apple's HomeKit platform and AirPlay if you use Apple devices rather than Alexa. Either way, you will likely want to put the speaker to good use to justify a price that's about twice as much as a Google Nest Protect.

On the safety side, the Safe & Sound holds up to the established reliability of the First Alert brand, with a photoelectric sensor and a carbon monoxide detector. It's a hardwired alarm designed to easily replace your existing hardwired detector with a sealed-in 10-year lithium battery backup. It also includes a night light with customizable brightness and colors to help guide you in the dark.

Power Source: Hardwired; lithium battery backup | Compatibility: Wi-Fi, Bluetooth, Amazon Alexa, Apple HomeKit | Sensors: Photoelectric, electrochemical | Extras: Carbon monoxide monitoring, voice prompts, smart speaker, customizable night light

What We Like

• Reliable smoke and CO detection

• Alexa and Apple HomeKit support

• Can interconnect with other alarms

What We Don't Like

• Delayed notifications

• No battery or sensor self-checks

For users of Apple iPhones, iPads, and the Siri voice assistant, finding devices that work with Apple's HomeKit smart home ecosystem isn't always easy. Fortunately, there are smart smoke detector options for HomeKit users, including First Alert's Onelink Smart Smoke & Carbon Monoxide Alarm. Once you've connected it to your home Wi-Fi network and HomeKit, it can integrate with other HomeKit gadgets and any automations you've set up. This second-generation model is also compatible with Amazon Alexa for additional flexibility.

The Onelink smart alarm offers two-in-one smoke and carbon monoxide detection and the option to choose your power source: a hardwired model with a sealed 10-year battery backup or a version with a replaceable five-year battery and an easy-to-access battery door. The hardwired units can interconnect with compatible alarms, and the battery-operated ones can do so wirelessly. You also get remote app notifications common to smart smoke detectors, but Onelink notifications can be delayed and won't trigger if an interconnected alarm sounds as opposed to the main unit.

Power Source: Hardwired or battery | Compatibility: Wi-Fi, Amazon Alexa, Apple HomeKit | Sensors: Photoelectric, electrochemical | Extras: Carbon monoxide monitoring, voice prompts

What We Like

• Cheaper than most smart smoke detectors

• Provides remote alerts for non-smart detectors

• Simple to install and use

What We Don't Like

• Ring Alarm system required

• No actual smoke/CO sensors

• Needs to be near smoke/CO detector

Today's smart smoke detectors make it relatively efficient to connect your smoke alarms to the internet, but in certain situations a device like the Ring Alarm Smoke and CO Listener might be a worthwhile alternative. It's not a detector itself but a gadget that you install near an existing smoke or CO detector (within 6 inches in this case) that listens for when the alarm goes off. Hearing an alarm then triggers the notifications that get pushed to your phone.

Importantly, the Ring Alarm Smoke and CO Listener requires the presence of a Ring Alarm Security System, so it makes sense primarily if you already have that smart security platform protecting your home. If you do, the listener adds a straightforward, easy-to-install fire prevention element to the mix. It's worth noting that if you've signed up for professional monitoring through Ring, the listener will automatically dispatch the fire department to your home if it hears an alarm, with no way to cancel the call. This automation makes false alarms potentially costly affairs.

Power Source: Lithium battery | Compatibility: Ring Alarm Security System (Z-Wave) | Sensors: Not applicable | Extras: None

What We Like

• Support for Z-Wave hubs

• Reliable smoke and CO detection

• Affordably priced

What We Don't Like

• No hardwired option

• No voice features

• No battery or sensor self-checks

Setting up your house with Z-Wave, a wireless mesh network (devices that work together to form one Wi-Fi network) generally dedicated to smart home systems, can offer several advantages over using more traditional Wi-Fi-only products. First Alert's 2-in-1 Z-Wave Wireless Smoke Detector & Carbon Monoxide Alarm (sometimes called ZCOMBO) is a smart detector ideal for Z-Wave-based smart hubs like Samsung SmartThings, Ring Alarm, or Nexia Home Intelligence. But it's incompatible with Wink or First Alert's own Onelink system.

Besides using a different wireless protocol, the Z-wave alarm works similarly to other smart smoke detectors. It sends mobile alerts through the smart home app you connect to, though it lacks extra features like voice prompts or self-checks. A photoelectric smoke sensor and an electrochemical CO sensor give it more versatility and convenience, as does an easily accessible battery compartment for basic AA batteries. However, there's no option for hardwiring it to your electrical system or wirelessly interconnecting it with alarms outside of your smart hub.

Power Source: Replaceable AA batteries | Compatibility: Z-Wave, Ring Alarm, Samsung SmartThings, Nexia Home Intelligence | Sensors: Photoelectric, electrochemical | Extras: Carbon monoxide monitoring

What We Like

• Hub and six alarms included

• Sensor and battery self-checks

• Good value

What We Don't Like

• Committing to a full set

• No carbon monoxide monitoring

• No hardwired option

The X-Sense Fire Safety System isn't a single smoke detector but rather a set of six smart alarms (model XS03-iWX) and the required X-Sense SBS10 Base Station that serves as their hub. It's a cost-effective starter kit if you know you want multiple smart alarms throughout your house, with individual units that work together and a network dedicated to keeping them connected.

Installing the system involves connecting the base station to Wi-Fi and syncing the wireless smoke detectors to the base station. If any of them detects smoke, all alarms are triggered, and instant notifications go to the mobile app, where you can silence the alert if it's a false alarm. While you won't get carbon monoxide monitoring, each unit performs automatic checks of its sensors and replaceable batteries every 60 seconds, with any issues pushed to the app. If you want to expand your system, you can purchase individual add-on XS03-iWX alarms to a maximum of 32 units.

Power Source: Replaceable CR123A lithium battery | Compatibility: Wi-Fi, X-Sense app | Sensors: Photoelectric | Extras: Battery self-check

Final Verdict

The Google Nest Protect, while pricey, has the safety and convenience features that make smart smoke detectors worthwhile—advanced smoke and carbon monoxide sensors, pre-siren remote warnings, frequent self-checks, voice prompts, and helpful motion-sensing light. As a less expensive option, the X-Sense XS03-WX Wi-Fi Smoke Detector still delivers real-time mobile alerts and the ability to check the status or silence alarms from afar.

Power Source

The power source options for smart smoke detectors remain the same as smoke detectors in general. Some have replaceable batteries that you must check and replace regularly. Others can be hardwired to your home's electrical system to stay powered at all times, with a backup battery in case the power goes out.

Landeen recommends hardwiring but admits, "it's not always the most cost-effective to hardwire an entire system." Instead of a hardwired setup, he recommends "at least have battery-operated alarms in place and be very mindful of when the battery should be replaced."

Sensors

Smoke detectors primarily use one of two types of sensor technologies: photoelectric and ionization. Photoelectric sensors tend to be more responsive to fires that have been smoldering for some time, while ionization sensors are quicker to pick up on flaming fires. Since dangerous house fires can be of either type, the recommendation is to have alarms with both types of sensors in your home.

Some smoke alarms use a combination of both sensor technologies. Currently, the only smart detector with the combined capability is the Google Nest Protect with its Split-Spectrum Sensor.

Advanced Features

One important distinguishing feature between smoke detectors is detecting dangerous levels of carbon monoxide (CO). Two-in-one detectors often cost more but save you the need for separate CO monitoring devices in critical areas, such as near the kitchen, garage, furnace, and bedrooms.

Another safety function of some smart smoke detectors is recurring automated checks of their sensors and battery to catch any issues between manual testing by the user. Other features like voice prompts or light indicators are offered mostly for convenience but can sometimes be surprisingly valuable in day-to-day use.

"I would go with a smoke detector like the Google Nest Protect that enunciates the location of the alarm, which is always important when it comes to exiting the building in a safe manner," says Landeen. "They also act as a motion-sensing night light in the ceiling, helpful especially if you have a dark walk to the bathroom."

FAQ

• What do smart smoke detectors do?

  Smart smoke detectors, like any smoke alarm, are meant to provide early warning of a fire in your home so that everyone inside can get to safety. The "smart" element connects your smoke detector to the internet so that news of an alarm can immediately reach you through your phone even when you're away from home.

  Accessing your smoke detector from your phone can also have practical benefits outside of emergencies. Many products allow you to shut off or silence the alarm if you know it's a false alarm. You can also test the batteries or other aspects of the device and see if there are any problems, all without needing to touch the smoke detector.
  

• How do you install a smart smoke detector?

  Installation of battery-powered smart smoke detectors can be as simple as mounting the small device to your ceiling and connecting it to your home Wi-Fi network (or another wireless hub, depending on the product) to activate its smart features. For hardwired alarms, replacing existing units can be straightforward, but installing hardwired smoke detectors at new locations should be left to an electrician if you're not experienced with the work.

  "Generally speaking, these are outlets—power sources that you are installing at different locations," says Landeen. "If you have the option, or you're in the process of building or renovating your home, without a doubt, it's worth the extra money for a hardwired system."

• How many smart smoke detectors do I need in my home?

  In general, for smoke alarms, the National Fire Protection Association recommends at least one on every floor, inside each bedroom and outside each sleeping area, and near living spaces and stairways.

  As for placing smart smoke detectors, you can set some up as part of an interconnected system of smoke and/or CO alarms across your home. This setup lets you apply internet-enabled benefits to all of your alarms through just one smart smoke detector.

  "The interconnected portion is important," says Landeen. "Who's to say there's not a fire in the basement, and you're in a second-floor bedroom? The interconnected smoke detector will alert the entire home that there's a fire."
  

This article's author, Anton Galang, is a freelance writer and editor who has worked with consumer technology for over 15 years. Since 2019, he has covered and reviewed a wide range of hardware, gadgets, and smart home products for Lifewire and The Spruce.

With the smart smoke detector market still relatively small, Anton researched the features, specifications, and reviews for most of the top options available, along with alternatives that performed similar fire safety functions. Anton also spoke with Justin Landeen, vice president of business development and smart home installation manager for Penco Electric, who contributed insights and recommendations from his experience with smart smoke detector installation in the Chicago area.

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