Space Heater Safety Tips: How Not to Set a Fire

Space heater safety is a lot better than it used to be. Modern space heaters are heavily regulated, especially regarding exposed heating elements and automatic shut-off switches to prevent overheating when a heater tips over or has its vent covered by an errant drape.

I tested these protections on each of the WIRED Gear Team’s favorite space heaters, roughly knocking heaters over and standing warily by as I swaddled each heater in a cotton sheet atop concrete. Any heater that we recommend performed admirably on these tests, shutting down or modulating its power output to keep from overheating.

The statistics bear out the safety improvements to space heaters: The number of fires due to heating equipment in the United States has dropped by more than 40 percent in the years from 2000 to 2020, according to a study by the National Fire Protection Association.

But heating devices still reward great caution, as do all devices that pull a lot of energy over long periods. The vast majority of residential heating fires start with actual fire, according to the United States Fire Administration—specifically in fireplaces and fuel burners. But portable space heaters nonetheless accounted for more than a thousand fires in the US each year from 2017 to 2019, according to the USFA’s numbers.

This accounted for just 3 percent of heating fires overall, but these led to more than 40 percent of fatalities, in part because portable heaters tend to be placed precisely where people live and sleep, and because the resulting fires are far more likely to be unconfined.

So treat your space heater with the caution and skepticism that it deserves. Here are some quite simple space heater safety tips, courtesy of the fine federal experts at the USFA, the Consumer Product Safety Commission (CPSC), and the Association of Home Appliance Manufacturers (AHAM).

Observe the “3-foot rule.” The CSPC has a simple rule of thumb: Keep your space heater at least 3 feet away from anything flammable—pretty much the same amount of space that’s considered courteous between two people during polite conversation. Flammable materials includes bedding, drapes, furniture, the dress you were going to wear, stray socks or stockings, your food delivery bag, and that great book you’ve been reading. Generally, also avoid placing flammable stuff like pillows or drapes in a spot that might potentially fall atop the space heater or drape over them.

Be especially wary of really, really flammable things. Maybe you don’t need to be told this. But AHAM recommends that you keep your space heater far, far away from very flammable things like paint, gasoline, aerosols, and books of matches. Heating up things like this with dry air is asking for trouble.

Don’t leave a space heater unattended. “Unattended” includes sleeping. I know it’s cold out there some nights. I know it feels easier to sleep when you’re toasty. But while bedrooms account for a minuscule 4 percent of heating fires, such fires are also disproportionately fatal, according to NFPA statistics—accounting for 22 percent of deaths. If you insist on using a space heater in your bedroom at night, get a device like Vornado’s TAV10 ($140) or Dreo’s Polaris tower ($130) that has a timed shut-off—and use it, so it doesn’t run all night while you sleep. (Or, might we suggest a wonderful down comforter instead? So warmmmm.) But also, don’t leave a space heater running after leaving a room or going to bed: Space heaters left running in the main living room space account for nearly 50 percent of fatal fires, according to the NFPA.

Plug your heater directly into the outlet. This is a big one that’s often overlooked. Do not, basically ever, use extension cords or power strips with space heaters. The added cord length builds up electrical load and can lead to shorts, overheating, and fires. If you must use a longer cord, consult an expert to ensure you get the proper gauge and rating for your space heater.

Use the thermostat function: OK, most space heater thermostats aren’t very accurate (though I do like the idea behind Vornado’s Sensa space heater (8/10, WIRED Recommends) with an external temperature sensor). But even if it’s off by a few degrees, using the thermostat instead of a temperature blast is good protection against overheating.

Place a space heater only on the floor, on a level surface. There’s no particular need to leave a space heater on a table or chair that might be unstable. Heat rises and travels around the room through convection. Don’t place your heaters atop thick shag rugs or carpets, either. Tight, short-pile carpets are often safe. If this is your only option, consider models like the Dyson HP07 ($550), which has heating outlets that are farther from the floor.

Don’t put rugs or other objects over the top of your space heater cord: Yes, it’s irritating to have the cord out where you can trip on it. But this is another case of making sure you protect the sanctity of the power cord, on devices that use this much power for extended periods. Putting heavy or edged objects atop the cord may damage or pinch it, potentially causing short circuits. Putting a rug on top of a cord will make it more likely that you step on the cord without noticing, thus also potentially damaging the cord. Damaging the cord is bad.

Don’t plug another appliance into the same outlet or circuit as the space heater. Maybe the worst thing that happens is you trip the circuit breaker. But that’s not fun, either. Most space heaters use 1,500 watts, the highest amount approved for consistent usage on 15-amp circuits.

Don’t leave a portable heater running unattended in a room with a baby, most sources say. The same advice goes for people with mobility issues. The risk isn’t just fire, but hyperthermia. This can be a delicate balancing act, of course.

Keep space heaters away from water and even general dankness. Bathrooms are famously dangerous places for high-wattage electrical devices. But also: You know that damp basement? The one that’s kinda cold and has puddles sometimes? Not a good place for a space heater.

Read the manual. Manufacturers have all kinds of good advice, as well as information about each device’s safety features and wattage used by the device.