The most common reason a space heater trips the breaker is circuit overload. A typical 1,500-watt heater draws about 12.5 amps — roughly 83% of a standard 15-amp circuit — so a few lights, a TV or chargers on the same circuit push the total past the limit. A loose outlet connection or a fault in the heater itself are the other usual causes.
Why it trips: the simple math
| Item | Typical draw |
|---|---|
| 1,500 W space heater | About 12.5 amps |
| Standard household circuit | 15 amps (about 1,800 W) |
| Headroom left for everything else | Roughly 2.5 amps — easily exceeded |
Move other loads off the circuit
- Unplug other devices on the same circuit
Lights, a TV, chargers and other appliances in the same room are often on the same breaker as the heater.
- Plug the heater in by itself
If it now runs without tripping, overload was the cause.
- Or move it to a different circuit
Pick an outlet in another room served by a separate breaker.
Never use an extension cord or power strip
Most heater manufacturers forbid extension cords and power strips, because they often cannot carry a heater’s current and can overheat before the breaker even trips. Plug the heater directly into a wall outlet — see our extension lead safety guide.
A worn or loose outlet
A weak or loose connection at the outlet adds resistance and heat, and can trip the breaker or damage the plug. If the plug or outlet feels hot, stop using it — see our burning smell outlet guide.
A fault inside the heater
A heater that trips even on an otherwise empty circuit may have an internal fault — a damaged element, faulty thermostat, or dust-clogged filter and fins. Clean the intake with the unit unplugged; if it still trips, replace the heater rather than repairing it.
A weakened breaker
A breaker that has tripped many times can weaken and trip at lower current than its rating. If a lightly loaded circuit trips repeatedly, have it tested rather than just resetting it.
When to call an electrician
Call an electrician if the heater trips on a lightly loaded circuit, the outlet or plug gets hot, or the breaker keeps tripping with nothing else on it. If the heater instead cuts out by itself without tripping the breaker, see our space heater shutoff guide.
