Guide · Breakers
Six causes, ordered by how often they are the answer. Only one of them means the heater is broken.
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A space heater trips a breaker because the circuit is carrying more current than the breaker allows — usually the heater's 12.5 A plus whatever else is plugged into the same circuit. Move the heater to a circuit of its own, or run it at a lower wattage. A genuinely faulty heater is the rarest cause.
A 1,500 W heater draws 12.5 amps at 120 V. A 15 A breaker allows 12 A of continuous load — that is the 80% figure that comes out of the NEC's 125% sizing rule for loads running three hours or more. So a full-output space heater is already slightly over the continuous allowance of a standard household circuit before anything else is plugged in.
| Heater | Draw at 120 V | 15 A circuit (12 A limit) | 20 A circuit (16 A limit) |
|---|---|---|---|
| 750 W | 6.3 A | Fits | Fits |
| 900 W | 7.5 A | Fits | Fits |
| 1,200 W | 10.0 A | Fits | Fits |
| 1,500 W | 12.5 A | Over the limit | Fits |
| Maximum continuous | — | 12 A = 1,440 W | 16 A = 1,920 W |
Draw computed as watts / 120 V. The continuous limit is 80% of the breaker rating, which follows from the NEC's requirement to size a circuit at 125% of a continuous load (NFPA 70, 210.19(A)(1) and 210.20(A)).
This is not a defect in your heater and it is not unique to the brand you bought. It is the arithmetic of every 1,500 W plug-in heater sold in the United States, and it is worked through completely on a 1,500 watt heater on a 15 amp circuit. What that page explains is *why the ceiling exists*. This page is about what to do when you have hit it.
This is the answer most of the time. A breaker protects a circuit, not a room, and a single 15 A circuit in an older house routinely serves a bedroom, a hallway and part of another room. Your heater at 12.5 A plus a 700 W microwave at 5.8 A is 18.3 A on a 15 A breaker, and the breaker is doing precisely its job.
How to confirm it: switch the breaker off and walk the house noting what died. People are almost always surprised by the answer. Then run the heater with everything else on that list unplugged.
A 12.5 A continuous load on a household extension cord is the single most dangerous thing in this list, and it can present as nuisance tripping before it presents as anything worse. Many power strips also contain their own overcurrent protection, which will trip at a lower threshold than the breaker. Plug the heater directly into a wall outlet — always, without exception. Why extension cords fail with space heaters covers the mechanism.
If the tripping device is an arc-fault (AFCI) or ground-fault (GFCI) breaker or outlet — bedrooms and bathrooms respectively, in modern construction — then it may not be tripping on current at all. These devices watch for electrical signatures rather than load, and a heater's thermostat switching a large resistive load on and off can occasionally look like one.
How to tell: an overload trip happens after the heater has been running a while and has a distinct “too much load” pattern; a GFCI trip is typically immediate and repeatable. A GFCI that trips the instant a particular heater is switched on, every single time, is telling you something real about that heater and it should be retired.
Look at the number on the breaker handle. A 20 A circuit allows 16 A continuous, which comfortably accommodates a 1,500 W heater and leaves headroom. A 15 A circuit allows 12 A and does not. Kitchens and garages often have 20 A circuits; bedrooms usually do not. This single check resolves a surprising number of cases and costs nothing.
Two 1,500 W heaters draw 25 A between them. If they are on the same circuit — and in an apartment or an older house they very often are, even in different rooms — no breaker in a residential panel will carry that. This is worth stating because the instinct when one heater is not keeping up is to add another, which reliably produces the tripping the person was not previously having.
Last, because it is genuinely last. A heater with a failing element, a damaged cord or a degraded internal connection can draw more than its rating or fault to ground. The signature is a heater that trips a circuit you have proven is otherwise empty, or one that trips immediately and repeatably on any circuit you try. If it also smells, stop there — see what a burning smell from a space heater means.
If moving the heater to its own circuit is not possible — and in a rental it frequently is not — the reliable remedy is to stop asking for 1,500 W. A heater with a published low setting lets you do that deliberately rather than by guesswork.
| Setting | Draw | Share of a 15 A continuous allowance | Cost per hour |
|---|---|---|---|
| 1,500 W | 12.5 A | 104% — over on its own | 27.5¢ |
| 900 W | 7.5 A | 63% | 16.5¢ |
| 750 W | 6.3 A | 52% | 13.8¢ |
| 170 W (under-desk panel) | 1.4 A | 12% | 3.1¢ |
Current draw at 120 V, against a 15 A circuit's 12 A continuous allowance.
Note what that table also shows: the lower setting is cheaper in exactly the proportion you would expect, because every electric heater costs the same per watt. Dropping to 900 W solves the breaker problem and cuts the bill by 40% at the same time. What it costs you is heating capacity — 900 W covers about 90 sq ft at our sizing rule rather than 150.
The rate behind every figure on this site
18.34¢per kilowatt-hour
U.S. residential average for June 2026. EIA, Electric Power Monthly, Table 5.6.A, released August 26, 2026.
This is the most recent month EIA has published. Residential rates move seasonally and vary enormously by state — from roughly a dime per kilowatt-hour in parts of the South to more than 40¢ in Hawaii — so treat it as a national reference point, not as your rate.
Four units that either publish a genuine low wattage or draw so little that the question disappears. Each pick card shows the computed draw and circuit fit for both settings.
Ranked for fit, not for hype. Coverage and current draw are computed from each unit’s published wattage. Tap a row for the full write-up, or go straight to the listing.
| # | Product | Best for | Covers | Draw | Price |
|---|---|---|---|---|---|
| 1 |  BLACK+DECKER BHDC201The cheapest heater here that publishes its low wattage, which is the only way to know what the economical setting actually costs instead of guessing at it. | A published 750 W low setting for under $25 | 150 sq ft | 12.5 A | $22.99 · Check on Amazon |
| 2 |  Lasko 754201The 900 W low setting is the whole point: it is the rare listing that publishes both settings, so you can compute what the cheap mode actually costs instead of guessing. | One person at one desk | 150 sq ft | 12.5 A | $49.99 · Check on Amazon |
| 3 |  De'Longhi HMP1500A micathermic panel is a radiator that gave up its bulk: it radiates like oil-filled and warms up like ceramic, and it is about three inches deep so it can live against a wall. | A slim profile against a wall | 150 sq ft | 12.5 A | $129.95 · Check on Amazon |
| 4 |  Global Industrial panelFunctionally the same 170 W under-desk panel as the QMark, with the one control the QMark lacks — an adjustable thermostat, so it cycles instead of running until you remember it. | The same panel, with a thermostat | 17 sq ft | 1.4 A | $122.74 · Check on Amazon |
Coverage computed at 10 W/sq ft, average insulation, 8 ft ceiling. Draw computed as watts ÷ volts. Neither figure is a manufacturer claim.
Top pick · A published 750 W low setting for under $25
The cheapest heater here that publishes its low wattage, which is the only way to know what the economical setting actually costs instead of guessing at it.
| Published specification | |
|---|---|
| Rated power | 1,500 W high / 750 W low, at 120 V |
| Controls | Four-position switch — off, fan, low, high |
| Thermostat | Adjustable |
| Other modes | Fan-only |
| Safety | Overheat protection and tip-over auto shut-off |
| Heat type | Ceramic (PTC) |
| Maker’s coverage claim | None published — the coverage figure above is ours |
| Safety listing | No listing mark is published in the listing text; check the rating plate for UL or ETL. |
Who it is for
A desk, a home office or a small bedroom where the 750 W setting will do most of the work and the 1,500 W setting is there for the cold snap.
What it is not for
A large or drafty room. At 750 W it covers about 75 sq ft at our sizing rule, and at 1,500 W it is still a personal heater in a small cabinet.
2 · One person at one desk
The 900 W low setting is the whole point: it is the rare listing that publishes both settings, so you can compute what the cheap mode actually costs instead of guessing.
| Published specification | |
|---|---|
| Rated power | 1,500 W high / 900 W low, at 120 V |
| Thermostat | Adjustable dial; 2 heat settings plus fan-only |
| Size | 9.2 x 7 x 6 in, 2.93 lb |
| Cord | 6 ft (Lasko's published figure) |
| Safety | Tip-over switch, overheat protection, cool-touch housing |
| Warranty | 3 years |
| Heat type | Ceramic (PTC) |
| Maker’s coverage claim | 100 sq ft |
| Safety listing | ETL listed, per Lasko's published specification — one of the few in this roundup that names a mark rather than leaving it to the rating plate. |
Who it is for
A desk, a small office, a dorm room — somewhere you want heat on a person rather than in a room.
What it is not for
A nursery, and not unattended use. It publishes a tip-over switch and overheat protection, but no child lock — and the USFA's advice to switch a heater off when you leave the room applies to every unit on this site, listed or not.
3 · A slim profile against a wall
A micathermic panel is a radiator that gave up its bulk: it radiates like oil-filled and warms up like ceramic, and it is about three inches deep so it can live against a wall.
| Published specification | |
|---|---|
| Rated power | 1,500 W high / 750 W low, at 120 V |
| Element | Mica panel — radiant plus convection, no fan |
| Mounting | Freestanding or wall-mountable |
| Controls | Adjustable thermostat, two heat settings |
| Frost mode | Standby setting holding the room above 41°F |
| Safety | Thermal shut-off, internal tip-over switch, standby setting |
| Heat type | Micathermic |
| Maker’s coverage claim | None published — the coverage figure above is ours |
| Safety listing | No listing mark published in the listing text; verify the UL or ETL mark on the rating plate. |
Who it is for
A room where floor space is tight and fan noise is unwelcome — a small bedroom, a study, a hallway landing.
What it is not for
A nursery or a household with toddlers, unless it is wall-mounted well out of reach. A hot panel at knee height is a burn, not a fire.
4 · The same panel, with a thermostat
Functionally the same 170 W under-desk panel as the QMark, with the one control the QMark lacks — an adjustable thermostat, so it cycles instead of running until you remember it.
| Published specification | |
|---|---|
| Rated power | 170 W at 120 V |
| Controls | Adjustable thermostat |
| Dimensions | 22-7/16" W x 14-14/16" H |
| Mounting | Floor mount, compact under-desk design |
| Finish | White |
| Heat type | Radiant panel |
| Maker’s coverage claim | None published — the coverage figure above is ours |
| Safety listing | No listing mark published in the listing text; check the rating plate for the UL or ETL mark. |
Who it is for
The same desk-bound reader as the QMark, who would rather the panel cycled on a thermostat than stayed on until switched off.
What it is not for
Anyone wanting a room warm. It is a leg warmer with a thermostat, and that is the correct expectation to have of it.
None of the above is something to work around with a different heater. A circuit that trips empty has a fault in it, and the heater was only the thing that revealed it.
If the heater runs but misbehaves in some other way — cutting out after a few minutes, blowing cold, or smelling wrong — that is a different ladder. Space heater maintenance has the symptom table, and the short answer is usually that the inlet is blocked rather than that anything has broken.
Almost always because the circuit is carrying more than the breaker allows. A 1,500 W heater draws 12.5 A on its own, against a 15 A circuit's 12 A continuous allowance, so anything else on that circuit pushes it over. A faulty heater is the least likely explanation.
No, and this is dangerous. The breaker is sized to protect the wire in the wall, not the appliance. A 15 A circuit is typically wired in 14-gauge conductor that is not rated for 20 A, so fitting a 20 A breaker leaves undersized wire unprotected against an overload.
Anything at or below about 1,400 W has a theoretical chance, but for genuine headroom on a shared circuit use 900 W (7.5 A) or less. A 900 W setting occupies 63% of the 12 A continuous allowance and leaves room for lighting and electronics on the same circuit.
A GFCI watches for current leaking to ground rather than for overload, so an immediate, repeatable trip is a different signal from an overload. If one specific heater trips a GFCI every time it is switched on, that heater should be taken out of service rather than moved to a non-GFCI outlet.
Not at full output. Two 1,500 W heaters draw 25 A between them, well beyond any residential 15 or 20 A circuit. Two heaters are only workable if they are on genuinely separate circuits, which in an apartment or older house is less common than people assume.
12.5 A against a 12 A continuous limit — the arithmetic nobody publishes, and what to do about it.
Why 12.5 continuous amps through a cord is the wrong tool, and what to do when the outlet is too far.
Chosen for a lease, a shared breaker panel and a neighbor through the wall — not for a floor plan.
Usually hot dust, and it stops in twenty minutes. Four smells mean unplug it and do not plug it back in.
Where the 750 / 1000 / 1500 W tiers come from, and why 1500 W is a hard ceiling on a U.S. outlet.
A $23 heater makes the same heat as a $460 one. Here is what the money actually buys, and what it does not.
Four things worth doing, none of which is opening the cabinet — and the four signs it is finished.