A smoke alarm.
Photo-Illustration: Lacey Browne/Consumer Reports, iStock

Always assume a sounding smoke alarm means there’s a fire and get to safety if need be. 

But what about when your smoke alarm sounds and it's a false alarm—but then it doesn't turn off? In 2019, 31 percent of false alarms that fire departments responded to were caused by system malfunctions, which include smoke alarms, CO alarms, heat detectors, and other systems, according to the National Fire Protection Association. Those mistakes can be caused by dust, humidity, electrical malfunctions, and even spiders crawling inside smoke detectors, says Bernie Deitrick, a senior test engineer at CR.

To know how to resolve a false alarm quickly, you first need to understand how your home’s smoke alarms operate. There are three types of smoke alarm power sources:

• Replaceable batteries
• Long-life lithium batteries
• 120-volt hardwiring (with batteries as backup power sources)

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Your approach should vary based on the type of power your smoke alarm uses. Your first step is to find the device that’s going off and reset it by pressing and holding the reset button.

If that doesn’t work, take the smoke alarm down. If you can, remove the batteries. If your smoke alarm has a lithium battery you can’t take out, muffle it in a blanket, under a sofa cushion, or in your freezer until it stops.

As for hardwired smoke alarms, "they’re interconnected through the electrical wires, so if one smoke alarm sounds, they’ll all sound and it can be difficult to figure out what’s going on," Deitrick says. First, try the reset button on each smoke alarm. If that doesn’t work, flipping the circuit breaker off and back on might stop the noise. If all of that fails, your ultimate solution may be to disconnect the smoke alarms and remove their batteries one by one. A small connector at the back of each alarm can be unclipped to let you safely remove it from the network.

Then it may be time for new smoke alarms. Here, you'll find some of the top picks from our tests, listed in alphabetical order. For more options, check our smoke and CO detector ratings and our smoke & CO detector buying guide.

Top-Rated Smoke Alarms From CR's Tests

Quick Take

First Alert 3120B

Price: $30

Flaming fires
Smoldering fires
Unlock Smoke & Carbon Monoxide Detectors Ratings
Quick Take

First Alert SA320CN

Price: $23

Flaming fires
Smoldering fires
Unlock Smoke & Carbon Monoxide Detectors Ratings
Quick Take

Kidde PI2010

Price: $30

Flaming fires
Smoldering fires
Unlock Smoke & Carbon Monoxide Detectors Ratings

Editor's Note: A version of this article also appeared in the September 2016 issue of Consumer Reports magazine.