Space Heater Keeps Tripping the Breaker? Causes and Safe Fixes

A space heater usually trips the breaker because the circuit is overloaded. A 1,500 W heater can use most of a 15 A circuit on its own, so a second device on the same circuit tips it over. Unplug everything else, use the low setting, or move the heater to another circuit. If it still trips, stop using it and have the heater or the circuit checked.

A breaker that trips is doing its job: it stops the wiring in your walls from overheating. This guide helps you find out whether the cause is simply too much load or a real fault.

Common causes

• Overloaded circuit. Space heaters (about 1,500 W), hair dryers (about 1,800 W) and window air conditioners (about 1,200 W) can each use most of a circuit by themselves.
• Other devices on the same circuit. Lamps, TVs and a second heater add up. Rooms often share a circuit with the next room.
• Extension cords and power strips. They add resistance and heat, and they can trip the breaker or fail.
• A worn breaker. Breakers age and can trip at lower current than their rating.
• A faulty heater. A damaged cord, a failing thermostat or an internal short can trip a breaker with no other load.

What the pattern tells you

How to fix it

1. Unplug the heater and reset the breaker. If it trips again with nothing plugged in, stop and call an electrician.
2. Unplug everything else on that circuit. Lights and chargers are fine to leave, but move TVs, hair dryers and other heaters elsewhere.
3. Plug the heater straight into the wall. No extension cord, no power strip.
4. Try the low setting. Many heaters have a 750 W setting that may stop the tripping.
5. Test a different circuit. If it runs fine there, the first circuit was the problem.
6. Inspect the cord and plug. Look for cracks, scorch marks or a plug that feels hot.

If you want to know what running it costs, see the electricity cost of a space heater.

Do the math before you plug it in

A 1,500-watt space heater at 120 volts draws 12.5 amps. A 15-amp breaker is rated for 15 amps, but a common guideline is to keep steady loads to about 80 percent of the rating, which is 12 amps. That means a 1,500-watt heater on its own already sits right at the limit of a 15-amp circuit, and a lamp, a TV or a phone charger on the same circuit can tip it over. On a 20-amp circuit the 80 percent figure is 16 amps, which leaves more room. You can try your own mix of appliances in the breaker load tool.

The low setting is much gentler. Many heaters use about 750 watts on low, which is about 6.3 amps, and that is why the low setting often stops the tripping.

Which kind of heater you have matters less than the wattage

Ceramic, oil-filled and infrared plug-in heaters sold in the US are mostly capped at about 1,500 watts, so they put a similar load on the circuit. What changes is how they deliver heat and how long they cycle. A heater with a working thermostat shuts off when the room is warm, which lowers the average load. Use the label rating, not the type, to decide what else can share the circuit.

Warm plugs and outlets are a warning

If the plug, cord or wall outlet feels warm or hot, stop using the heater and unplug it. Heat at the connection can come from a loose or worn outlet, a damaged plug or an extension cord that cannot carry the load. A breaker that trips is working as intended, but a plug that is hot is a fire risk even when the breaker does not trip. Have an electrician look at the outlet before using it again.

To see what the heater costs per hour and per month, try the running cost estimator. If you are not sure the heater is the right size for the room, a room sizing tool shows the watts you need.

When to call a professional

Call a licensed electrician if:

• The breaker trips with only the heater running, on more than one circuit.
• An outlet, plug or cover is warm, discolored or smells of burning.
• The breaker will not reset, or trips immediately with nothing plugged in.
• You need a heater in a room whose circuit is already crowded.

Replace the heater if the cord is damaged or it trips on every circuit. Other kitchen and laundry appliances can overload a circuit in the same way, as in an air fryer that trips the breaker.

What not to do

• Do not keep resetting a breaker that trips at once.
• Do not run two heaters on one circuit.
• Do not tape over or bypass the breaker.
• Do not leave a heater running unattended on an overloaded circuit.

Not sure a heater is the right size for the room? The room-size heater calculator gives the watts you need.

Bottom line

Most space heater trips are overloads. Give the heater its own circuit, plug it into the wall and use the low setting if needed. If it still trips on its own, treat that as a fault and get it checked. If the power goes out entirely, see how to prepare for a power outage.