Space Heater Power Requirements at a Glance#
A portable space heater is a heavy 120-volt load for its size, drawing 11 to 13 amps for 1,300 to 1,500 watts on a 15 to 20-amp branch through a 5-15R outlet. A fan-forced model and an oil-filled radiator both land in that same range.
Space Heater Electrical Specifications#
| Configuration | Voltage | Amps | Watts (max load) | Breaker | Outlet (NEMA) |
|---|---|---|---|---|---|
| Portable 120-volt space heater | 120 V | 12–13 A | 1,400–1,500 W | 15–20 A | 5-15R |
| Oil-filled radiator heater | 120 V | 11–13 A | 1,300–1,500 W | 15 A | 5-15R |
A portable space heater pulls almost the full safe current a household circuit can carry for hours at a time, which is exactly why plugging it into a shared outlet with other loads so often trips the breaker or overheats the receptacle. It should have a wall outlet more or less to itself and never lean on an extension cord.
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Circuit and Breaker Sizing for the Space Heater#
At 11 to 13 amps a space heater consumes nearly the entire safe capacity of a 15-amp branch, and it does so for hours at a stretch. Standard 14-gauge wiring carries it, but only if little else shares the circuit — which is why the heater really wants a wall outlet more or less to itself. Pair it with a television, a lamp and a phone charger and the branch is fine; add a second heater or a microwave and the breaker drops.
Installation and Safety Notes for Space Heater Wiring#
The heater plugs into a wall 5-15R outlet with its own cord, and the single most important rule is to skip the extension cord entirely — a thin cord overheats under this near-continuous load and is a leading cause of fires. Plug it straight into the wall, ideally on a circuit it does not share. No permit or electrician is involved in using one, though adding an outlet so it need not reach across a room is worth an electrician's visit.
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Space Heater Electrical FAQ#
Why does a space heater trip the breaker so easily?#
At 11 to 13 amps it nearly fills a 15-amp branch by itself. Adding almost any second load pushes the circuit past its limit and trips the breaker.
What breaker should a 1,500-watt heater run on?#
A 15 to 20-amp branch through a 5-15R outlet. The heater draws 11 to 13 amps, so a 20-amp circuit gives useful headroom.
Can a space heater share an outlet with other things?#
Only with light loads like a lamp or charger. A second heater, a microwave, or another heavy appliance on the same branch will trip it.
Is it safe to run a space heater on an extension cord?#
No. A space heater's sustained 11 to 13-amp draw can overheat an extension cord and start a fire. Plug it directly into a wall outlet.
How much current does a portable heater draw?#
A portable space heater and an oil-filled radiator both pull 11 to 13 amps for 1,300 to 1,500 watts, held steadily while heating.
Should a space heater have its own outlet?#
Ideally yes. Because it draws close to a full 15-amp branch, it runs safest on a wall outlet it does not share with another significant load.
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