Intech Blog

Space Heaters and Overloaded Circuits: Fall Safety for MN Homes

Published September 5, 2026 · Intech Corporation · Twin Cities, MN

A standard 1,500-watt space heater draws about 12.5 amps, which is nearly everything a 15-amp household circuit is rated to carry. Plug that heater into an outlet that's already feeding a lamp, a phone charger, or a window fan, and you've got a recipe for a tripped breaker at best and an overheated cord at worst. The safest move is to give a heater its own outlet on its own circuit, never run it through an extension cord or power strip, and call an electrician if a breaker keeps tripping or an outlet feels warm to the touch.

Minneapolis and St. Paul don't hit reliable freezing temperatures until early October, but the shoulder season is exactly when space heaters come out of the closet. Bedrooms, home offices, and finished basements cool off faster than the rest of the house, and rather than crank the whole furnace, a lot of people just plug in a heater for a few hours in the evening. That's a reasonable instinct. It's also the single biggest driver of home heating fires and breaker trips every fall and winter.

This isn't a fringe risk. The U.S. Consumer Product Safety Commission estimates that portable heaters, including electric space heaters, are involved in an average of 1,600 fires per year, and the National Fire Protection Association says the peak months for home heating fires are December, January, and February, right when Minnesotans are running heaters the hardest. If you've already dealt with breakers tripping during a heat wave, the same overloaded-circuit logic applies here, just with a heater instead of an air conditioner.

Why space heaters cause a disproportionate number of fires

Heating equipment overall is a major cause of home fires, but space heaters carry an outsized share of the damage. According to NFPA data, space heaters and heating stoves are involved in roughly one out of every three home heating fires, yet they account for close to eight out of ten of the resulting deaths and about seven out of ten of the injuries. The most recent NFPA figures put the annual average at over 37,000 home heating equipment fires, resulting in several hundred deaths and well over a billion dollars in property damage nationwide.

Most of that risk comes down to two things: heaters placed too close to something flammable, and heaters plugged into circuits or extension cords that can't handle the load. Both are preventable, and neither requires anything more than good habits and, when the wiring itself is the problem, a call to a licensed electrician.

How much power a space heater actually pulls

The math here is simple and worth knowing. A 1,500-watt heater running on a standard 120-volt outlet draws 12.5 amps. A 15-amp circuit, the most common type in older homes, is only rated to carry that load reliably if nothing else is sharing it. Add a box fan, a phone charger, or a lamp to the same circuit and you're pushing right up against the breaker's limit, which is exactly why it trips. A 20-amp circuit gives you more headroom, which is why most electricians recommend one for any room where a space heater runs regularly.

This is also why a heater should always plug straight into a wall outlet. The Consumer Product Safety Commission is explicit about this one: plug electric space heaters directly into a wall outlet, never into an extension cord or power strip. Cords and power strips aren't built for that kind of sustained current, and they're a common point of failure when a heater has been running for hours.

Warning signs you shouldn't wait on

You don't need any special tools to catch most of the warning signs before they turn into a bigger problem. Here's what should make you unplug a heater and stop using that outlet.

• A breaker that trips more than once with a space heater plugged in, even with nothing else on that circuit.
• An outlet, plug, or cord that feels warm or hot to the touch, or shows any discoloration or melting around the faceplate.
• A burning smell near an outlet or panel that isn't coming from the heater itself.
• Flickering lights on the same circuit when the heater kicks on.
• A loose-fitting plug that wiggles in the outlet instead of seating firmly.

When it's time to call an electrician instead of resetting the breaker

Resetting a tripped breaker once is fine. If it trips again right after you plug the heater back in, that's the circuit telling you it's already carrying its limit, or that something in the wiring isn't right. That's not a DIY fix. In homes built before the 1970s, especially those with two-prong, ungrounded outlets or aluminum branch wiring, a heater is often the appliance that finally exposes wiring that's been marginal for years. An electrician can check load on the panel, add a dedicated circuit where it makes sense, and confirm the wiring behind the wall is actually rated for what you're asking it to do.

If you're not sure whether your panel has room to spare, especially if you've also added a heat pump, an EV charger, or other big loads in the last few years, it's worth having someone look at the whole picture rather than guessing room by room. Our panel upgrade and troubleshooting teams handle this exact kind of call constantly heading into fall.

If you need heat in the same spot every year, consider a permanent option

If a particular room, a bonus space over the garage, a converted attic, a chilly basement office, needs supplemental heat every single fall and winter, a plug-in heater dragged out of a closet isn't really a long-term answer. A hardwired wall heater or baseboard unit on its own dedicated circuit solves the overload problem permanently and tends to be safer around kids, pets, and cords underfoot. It's a straightforward job for a licensed electrician and usually a lot cheaper than most people expect.