Electric baseboard heat 120v vs 240v


Diamond Member
Dec 3, 2010
I have a basement powder room that's not connected to my central heat/air. There is a dedicated 120v circuit from my circuit breaker to the powder room ceiling fan that also has a heater feature but it doesn't heat very well. I was thinking of installing a baseboard heater instead. Using an online calculator it seems like I need 500w of heat in the room. I think I could run this on a 120v circuit but I'm reading a lot of sites suggest a 240v circuit. Is this necessary if I'm only using a 500w heater?


No Lifer
Nov 30, 2004
Dunno, but I've never had problems running a 1.5kw portable heater along with whatever minor draws are going on in the same room. Mine's an oil filled baseboard heater, and if kept on a low setting, will work effectively for a relatively small power draw, but it isn't instant heat. Takes a short amount of time to get going.


Senior member
Nov 22, 1999
We also use an oil filled radiant space heater. It is 1500 watts but we only use it at the low/medium {700 or 800 watt} settings, never had any problems using it most of the winter.


Diamond Member
Oct 22, 2001
500 watts at 120 volts is going to draw just over 4 amps. Most 120 volt circuit breakers will trip at 15 or 20 amps, so that added 4 amps for the heater shouldn't be much of a problem - provided there are no large loads (e.g. refrigerator, freezer, wash machine...) already on that circuit.

To put this into perspective, common household appliances such as hair dryers, toasters, and portable heaters (as mentioned earlier) often draw 1500-2000 watts (13-17 amps). If you were considering a heater of similar wattage then you might want to consider using a dedicated 120 volt circuit or a 240 volt circuit.

Red Squirrel

No Lifer
May 24, 2003
I don't think they make hard wire 120v baseboard heaters, at least I've never seen any. I think it is possible to run a 240v one on 120v as I don't think they have any electronics or circuitry in them that expects 240v, but they will run at 1/4 the wattage. So if you can fit a 1500w heater (they will be longer) you could run it at 120v and get around 375w out of it. Or put an outlet there with a plug in space heater. You can control the outlet with a thermostat if you want.

Personally I would just run a dedicated 240v circuit for it, but that does require a double pole breaker so if you don't have space in your panel you will have to start shuffling stuff around.

George Nasir

Sep 20, 2022
Although most electricians use the 240V heating circuit, it is frequently easiest to stay with 120V heaters when installing baseboard heaters on your own. The same wire type and size are used, but the 240V voltage allows for twice as much efficiency, and the resulting savings more than offset the higher breaker cost.


Platinum Member
Aug 17, 2006
No, 240 V does not give you higher efficiency. A simple electric heater that uses a resistive wire to create heat is one of the few types of electrical devices that is 100% efficient, regardless of voltage. What 240 V gets you, as others above have said, is the POSSIBILITY of getting heating power four times a high as the SAME heater on 120 V. BUT all that really means is that the higher heating power will have to actually run for one-quarter of the time to produce the SAME amount of heat. The impact of that is that a higher-power unit can heat the space up from cold more quickly, AND if the lower-power operation is NOT enough when running full time, a higher-power one will give you more heating rate than needed.

OP, you say the circuit in this bathroom is a dedicated 120 V circuit, probably on a 15 A breaker. The only load currently is room lights (maybe - you did not mention this), a venting fan (likely 1 to 3 A) plus some heating unit associated with the fan. THAT heating unit will be a load you need to consider. Your best bet may be to DISconnect the heating system in the fan unit and rely solely on the new heater. You have estimated that new one needs to be 500 W, which can fit easily into the amp rating of the breaker, and certainly CAN be a 120V plug-in unit, not necessarily hard-wired. You may need to install an outlet for this, and it SHOULD be a GFCI type for use in a bathroom. That needs to be the same Amps rating (or slightly less) as the breaker feeding this room. I would suggest you get a heater unit of 1,000 W or so (more common that 500 W) with a thermostat built in so you have lots of excess capacity just in case, but it still fits into the electrical load limit of the room IF the heater built into the fan is disconnected.


Diamond Member
Aug 11, 2001
You'll have plenty of margin to run a 500W heater off an existing 15A, 120V circuit, as long as nobody is trying to simultaneously use a 1500W+ hair dryer on the same circuit. The wall mount heater (that type) linked seems a good option given the details we have so far.