Can you Run Two Space Heaters at once? (Experiment Confirmed)

You can run two space heaters at once almost anywhere in the world except in the US. Why is that?

In this article, we’re going to find this out!

Quick answer: On regular US 120V wall outlets you can run two space heaters at once on reduced heating settings only (80% or less). On 220V-240V (eg. UK, Europe) power outlets you can run two space heaters on full power since more voltage means less amperage which means less tripping of circuit breakers.

While all other blogs on the web just do calculations, I simply tried running my two space heaters at once. Did a circuit breaker trip? Here’s the result:

Answer: Can you run two space heaters at once?

Here’s the answer to whether you can run two space heaters simultaneously in your home. If you have a 15A circuit, check the first table. For 20A circuits, check the second table.

Then look up the power of your heaters and see in the ‘Can you run two heaters’ columns whether you can run your heater.

• Use the 120V column if you live in North America
• Use the 230V column if you live in Europe, the UK, or Australia

For 15A circuits:

For 20A circuits:

Recommendation: Safe space heaters you can run simultaneously on one circuit

I’ve written an article on safe space heaters that don’t blow fuses (click here to view it). There, I generally recommend using space heater models that come with a built-in ECO mode, which consumes 1,000W of power or less.

In the US you can’t run many heaters on one circuit due to the 120V outlet. The heaters recommended in this article are safe to run simultaneously.

Check the article, if you live in the US and you are looking for the right heater!

Experiment: I tried to run two space heaters simultaneously

Before crunching any numbers, I decided to test whether I can run two space heaters simultaneously myself.

I am a proud owner of two space heaters. One is a 2,500W oil-filled radiator. The other is an 800W infrared heater. So, both together are able to deliver a total heat output of 3300W. That’s quite a number.

Most space heaters run on 1,500W. So, the 3,300W combined from my space heaters is even more than running two regular 1,500W heaters.

Experiment Result: What happens when I run two space heaters at once?

NOTHING.

The heaters turned on. They started heating. No fuses or circuit breakers were harmed in the making of this experiment. Literally, nothing happened. The two space heaters ran as if nothing special was going on.

Why am I able to run two space heaters at once?

I live in Europe. In Europe, in the UK, and, actually, in most countries of the world, the wall outlets provide 230V of power. In the US it’s a measly 120V.

The more power we receive through voltage, the less current (amperage) is required. Less current requires a lower wire gauge, which makes it less likely to blow fuses and trip circuit breakers.

My two space heaters draw a combined amperage of 3300W/240V = 13.75A.

This is well below the 15A (or 20A) limit most circuit breakers have.

And that’s why I am able to run two space heaters on full power.

Sorry, America!

Now, we know that almost all outlets in the world can handle two space heaters simultaneously. Let’s check the situation for 120V US outlets.

Will 2 space heaters trip the circuit breaker?

One 1,500W space heater draws 12.5A on a 120V wall outlet. A regular circuit breaker trips at 15A – 20A.

So, one space heater can always run on full power.

Two space heaters will trip the circuit breaker if both heaters run on full power. They won’t trip the circuit breaker if they run on reduced power.

It does not matter whether you achieve the reduced power by reducing both space heater’s power settings, or by reducing one space heater’s power setting a lot and running the other on full power.

The only metric that matters for tripping circuit breakers is the combined power consumption (and, therefore, the amperage) of both heaters.

Can you run two space heaters on one circuit?

Yes, you can run two space heaters on one circuit, if each space heater draws less than half the amperage your circuit is rated for.

If your circuit is 20 Amps, then each space heater should draw less than 10 Amps.

A 1,500W space heater draws 12.5A. Therefore, you have to reduce the heating setting by at least 20% so it draws only 10A.

Then, two space heaters will draw 20A combined and you can run them on one circuit.

For a 15A circuit, you should reduce the amperage of each space heater to 7.5A. That’s a reduction of the heat setting by 40%.

As a rule of thumb: You can run two space heaters on a 15A circuit only if you run each space heater at half power settings.

Note that you can’t run any other devices in that case, since that would overload your home’s circuit.

How many space heaters can I run on a 20-amp breaker?

On a 20-amp breaker, you can run 2 space heaters on 80% heating settings, or 3 space heaters on 50% heating settings. 

However, the total power output of a 120V outlet is capped at 2400W, so you can never produce more heat than 2,400W, and adding more space heaters (on lower settings) won’t make a difference.

You can check the specifications of your space heater to see how much you need to reduce the heating settings in order to safely run your space heater without tripping the breaker.

How many watts can I run on a 20-amp circuit?

On a 20-amp circuit, you can run a total of 20 amps × 120 volts = 2400 watts.

How many watts can I run on a 15-amp circuit?

On a 20-amp circuit, you can run a total of 15 amps × 120 volts = 1800 watts.

How many amps does a 1500-watt heater take?

A 1,500W space heater draws 12.5A from the wall outlet. You get this result by dividing the wattage by the voltage.

1,500W ÷ 120V = 12.5A.