Space heaters cause more house fires than almost anything else you own

Portable space heaters are consistently one of the leading causes of home heating fires in the US. The failure mode is almost always one of a handful of avoidable mistakes, repeated.

The rules that actually matter

• Three feet of clear space, on all sides. Nothing flammable — curtains, bedding, furniture, paper, pet beds — within three feet of any surface of the heater.
• Plug it directly into a wall outlet. Never into an extension cord or a power strip. Space heaters typically draw close to 1,500 watts, which is already near the safe limit of a standard 15-amp circuit (see amps, volts, watts) — a thin extension cord carrying that load is exactly the fire risk covered in why your extension cord might be a fire hazard.
• Never leave it running unattended, and never run one overnight in a room while you're asleep unless it's specifically rated and designed for that use with tip-over and overheat shutoff.
• Put it on a hard, level, non-flammable surface — not carpet, not a rug, not a table edge where it could tip.

Buy one with these two safety features

• Automatic tip-over shutoff — cuts power the instant the unit is knocked over
• Overheat protection — shuts the unit off if internal temperatures get dangerously high

Nearly every heater sold at a major retailer today has both, but older units — especially ones pulled out of storage from years ago — often don't. If a heater doesn't list these features, don't use it.

Where not to use one

• Bathrooms, unless the specific unit is rated for damp locations — water and electricity plus an unattended heat source is a bad combination
• Anywhere near water sources in general
• Small enclosed spaces without ventilation, especially for combustion-based heaters (propane, kerosene) which can produce carbon monoxide — see where smoke and CO detectors are legally required

The math on why this matters

Space heaters are popular specifically because central heating is expensive to run for one room. But a $30 heater used carelessly for one winter is a worse financial and safety outcome than the heating bill it was meant to offset.

Quick reference

• Three feet of clearance from anything flammable, always
• Plug directly into the wall — never an extension cord or power strip
• Never leave it running unattended or overnight unless it's rated for that
• Buy one with tip-over and overheat shutoff — most new units have both
• Keep off carpet, out of bathrooms, and away from bedding