Space Heater Safety: The Rules That Prevent Most Fires

Portable heaters are a small part of the home heating fire problem by count and a large part of it by harm. The U.S. Fire Administration reports that portable heater fires were only 3 percent of home heating fires in 2017 to 2019, but 41 percent of the fatal ones. The Consumer Product Safety Commission (CPSC) estimates that portable heaters, including electric space heaters, are involved in an average of 1,600 fires a year, with 70 deaths and 150 injuries (2020 to 2022).

The pattern behind those numbers is simple. A heater that is too close to bedding, plugged into a cord that overheats, or left running while people sleep can start a fire that nobody notices in time.

The rules, in order of importance

1. Keep a three-foot clear zone.Safe check

   Bedding, drapes, furniture, clothes, paper and anything else that can burn stay at least three feet from the heater, in every direction. This is the distance the CPSC and the U.S. Fire Administration both give.

2. Plug it directly into a wall outlet.Safe check

   Never an extension cord or a power strip. The CPSC warns that they can overload and start a fire. If the plug, the cord or the outlet cover feels hot, unplug the heater and stop using that outlet.

3. Turn it off when you leave the room or go to bed.Safe check

   Warm the bedroom before you get in, then switch the heater off. If you need heat overnight, that is a job for the home's heating system.

4. Put it on a hard, level floor.Safe check

   The CPSC says to place a heater on a level, hard and nonflammable surface, not on rugs or carpets. Shelves, beds and furniture are out.

5. Keep children and pets away from it.Safe check

   A heater can be knocked over or touched. The CPSC also warns about overheating: do not leave a heater running unattended in a closed room with an infant or with someone who cannot move away from the heat or call for help.

6. Let a fuel-burning heater cool before refueling.Take care

   Never refuel a kerosene or propane heater while it is running. Turn it off and let it cool first.

Where a heater can and cannot go

Why the wall outlet matters

A space heater is one of the heaviest loads you can plug into an ordinary outlet, and it runs for hours. Power strips and light-duty extension cords are not built for that.

The circuit matters too. The CPSC uses about 1,500 watts as the practical limit for a typical 15-amp household circuit and about 2,000 watts for a 20-amp circuit. A heater on its high setting takes the whole budget of a 15-amp circuit.

Current is watts divided by 120 volts. “Left over” is the CPSC’s practical limit for the circuit minus the heater’s draw. If the breaker trips when the heater and something else run together, that is the circuit doing its job. Move the other appliance to a different circuit; do not reach for an extension cord. See why a breaker keeps tripping for how to work out which outlets share a circuit.

Before the first cold night

• Look at the cord and plug. Cracked insulation, a loose plug or scorch marks mean the heater is finished.
• Check for recalls. Search the model at cpsc.gov/recalls. If it has been recalled, stop using it and contact the company for the remedy.
• Check its age and its label. The CPSC advises choosing a heater tested to current safety standards and certified by a nationally recognized testing laboratory. Current standards require electric and kerosene heaters to shut off if they tip over; an old heater may not.
• Test your alarms. The CPSC recommends smoke alarms on every level and inside each bedroom, carbon monoxide alarms on every level and outside sleeping areas, and a test every month. If one is chirping, see what smoke alarm beeps mean.

Why winter nights are the dangerous time

The National Fire Protection Association (NFPA) reports that nearly half of home heating equipment fires, 46 percent, happen in December, January and February. Space heaters and heating stoves account for about 30 percent of those fires but 73 percent of the deaths (2020 to 2024 averages).

Time of day matters as much as the season. In an earlier NFPA analysis covering 2016 to 2020, only 13 percent of heating fires started between midnight and 6 a.m., yet those fires caused about two in five of the deaths. People who are asleep have less time to react, which is the reason behind the rule about turning the heater off at bedtime.

Fuel-burning heaters need two more things

Kerosene, propane and gas heaters add a second hazard on top of fire: carbon monoxide. The CPSC says fuel-burning heating equipment can produce it when the equipment is installed incorrectly, poorly maintained, badly vented or misused.

• Have working carbon monoxide alarms on every level of the home and outside sleeping areas.
• If a carbon monoxide alarm sounds, get everyone outside and call 911. See what the beep patterns mean.

What it costs to run

Safety aside, a 1,500-watt heater is not cheap heat. Our guide to space heater running costs has cost tables by electricity rate, and the appliance energy cost calculator works out your own numbers.

If the heater smells, blows cool air or shows an error code, see common space heater problems and what they mean. If your heater keeps switching itself off, its safety devices may be doing their job: see why a space heater keeps turning off. If the lights dip when it starts, see why lights flicker.