When planning out your baseboard heater settings, it’s essential that you keep your amp breakers in mind. Most US households have a 20-amp circuit. The key question to answer is ‘how many baseboard heaters can you put on a 20-amp circuit?’.
The answer is quite self-evident: The net amp draw of all baseboard heaters on the same 20-amp breaker has to be less than 20 amps.
Now, the key question is how many amps do baseboard heaters draw. Voltage is the key here (due to the basic power equation; P = I x V).
We’ll look into how you calculate how many baseboard heaters can be put on a 20-amp circuit and check how many amps do baseboard heaters draw. We will also show 2 examples of perfect baseboard settings for a 20-amp circuit.
Here’s the summary on what is the maximum baseboard heating load that may be connected to on a 20 amp circuit breaker:
If you use 120V baseboard heaters, the 20-amp circuit can support a net total of 2,400 W. That’s one 2,000 W baseboard heaters or two 1,000 W baseboard heaters.
If you use 240V baseboard heaters, the 20-amp circuit can support a net total of 4,800 W. That’s two 2,000 W baseboard heaters or three 1,500 W baseboard heaters.
In short, a 20-amp circuit can handle anywhere from 2,400 W to 4,800 W of baseboard heater electric power input. It all depends on the voltage.
Let’s check how many amps do standard electric baseboard heaters draw:
How Many Amps Do Baseboard Heaters Draw?
Here’s how many amps do baseboard heaters on 120V and 240V draw:
| Baseboard Power: | Amp Draw (at 120V): | Amp Draw (at 240V): |
| 500 W | 4.17 amps | 2.08 amps |
| 750 W | 6.25 amps | 3.13 amps |
| 1,000 W | 8.33 amps | 4.17 amps |
| 1,500 W | 12.5 amps | 6.25 amps |
| 2,000 W | 16.67 amps | 8.33 amps |
| 3,000 W | 25 amps | 12.5 amps |
Let’s solve 2 examples to illustrate the difference the voltage makes when sizing baseboard heaters to a 20-amp circuit.
Example 1: How Many 1,500 W Baseboard Heaters Can You Hook Up To 20-Amp Circuit?
The standard power input for a baseboard heater is 1,500 W. We need to determine how many amps does a 1,500 W heater draw.
To calculate the amps, we use the basic electric power equation:
P (Watts) = I (Amps) x V (Volts)
We know the watts (electrical power) and volts (electrical potential). Let’s express the amps (electric current):
I (Amps) = P (Watts) / V (Volts)
We have a 1,500 baseboard heater. Let’s see how many amps does it need to run if we use a 120V circuit or a 240V circuit:
I (Amps at 120V) = 1,500 W / 120 V = 12.5 A
I (Amps at 120V) = 1,500 W / 240 V = 6.25 A
As we can see, the 1,500 W baseboard heater draws 12.5 amps at 120V, and 6.25 amps at 240V.
That means that we can use a 1,500 W baseboard heater on a 20-amp circuit.
However, if we have a 120V circuit, we can only use one 1,500 W heaters (it only has a 12.5 A draw). Why? Well, if we would connect two such heaters, the total amp draw would be 25 amps. This would surpass the capacity of a 20-amp circuit.
Here’s what’s interesting:
If we have a 240V circuit, we can connect up to three 1,500 W baseboard heaters. That’s because its net amp draw is 3 x 6.25 A = 18.75 A. This is less than 20 A.
That means that we can connect three 1,500 W heaters, netting a total output of 4,500 W, if we have a 240 V circuit. If we have a 120 V circuit, you can only connect one 1,500 W heater, with a net electric power input being only 1,500 W.
Note: We can also put one 120 V 1,500 W heater + one 240 V 1,500 W heater on a 20-amp circuit. This total amps here are 12.5 A + 6.25 A = 18.75 A; less than 20 A. In this way, a 20-amp circuit can support 3,000 W worth of electric baseboard heaters.
Example 2: Can We Put A 3,000 W Electric Baseboard Heater On A 20-Amp Circuit?
If we calculate a bit (or you can check the table above) we see that:
- At 120V, a 3,000 W baseboard heater draws 25 amps.
- At 240V, a 3,000 W baseboard heater draws 12.5 amps.
Now, a 20-amp circuit can only handle devices that draw up to 20 amps. We can see that, if we have a 240V circuit, we can run a 3,000 W heater on a 20-amp circuit. That’s because it draws less than 20 amps; 12.5 amps, to be exact.
Using the same reasoning, we can’t connect a 120V 3,000 W baseboard heater. That’s because it draws 25 amps; too much for a 20-amp circuit.
If you’re in a market for electric baseboard heaters, you are welcome to check out our list of the best electric baseboard heaters here. If you also have any questions about how big a baseboard heater you can connect to a 20-amp breaker, you can pose the question in the comments and we’ll try to help you out.
Q:your explanation that states you can have a 120 voltage baseboard heater and a 240 volt heater on the same circuit.
I’m no electrician,but I have a basic understanding,and what your implying is you can run both120 volt,and 240 volt on the same 240 volt circuit!
Seems like this is either wrong information,or your going to short out the 120 volt heater!possibly causing a fire,although I plugged my grinder into a modified 120 circuit that was looped to produce 240….it just ran faster…but for how long,before it burns out,same for the heater,although ,my point of veiw may be wrong,I just wanted to question your information!as I’m putting in a 2500 watt baseboard heater on 120,or do I need 240 circuit?
Hello David, basically you have to put a baseboard heater on a specified voltage (it’s written on the heater’s specs sheet). Mathematically speaking, you can put a 120V on a 240V circuit if you use the voltage transformer, and hence we keep the amp draw. Obviously, if you have 120V baseboard heaters, it makes sense to put them on a 120V circuit (and get the 2,400W max. power input), and if you have 240V heaters, put them on a 240V circuit (and get the 4,800W max. power input).
So can I put two 8 ft 2000W and a 30inch 500W baseboard heater on a 20 amp 240 breaker? Thank you.
Hi Susan, alright, the total wattage draw here is 4500W. If you have a 240-volt circuit, the amp draw is 4500W/240V = 18.75A. The 20 amp breaker can only be loaded up to 80% of its max. capacity; so the max. amp draw can be 16A. In short, the 20 amp 240V breaker is too small in this situation. You could use the 30 amp 240V breaker, for example. Hope this helps.