How to fix a Space Heater Cord getting Hot

Your space heater’s power cord is getting hot and you have no idea whether you should worry about it?

In this guide, we are going to check your space heater’s cord together.

My name is Daniel, I am an electrical engineer, and I have two space heaters at hand of which I am going to check cord temperatures.

One cord is getting hot, the other stays cool. But that’s normal. A space heater power cord getting hot is not necessarily dangerous.

In fact, some heat is expected. Let’s find out why and what to do about it.

There are dozens of websites spreading panic about space heater cords overheating. Let’s approach the whole situation with a calm and rational mind.

Let’s have a look.

How hot should a space heater cord get?

I have two electric space heaters at home, an infrared heater, and an oil-filled radiator.

All of them work just fine.

So, let’s see how hot their cords get.

Space heaterCord temperature (after 10 minutes)Description
Infrared heater (800W)75.3°F (24°C)Not hot at all
Oil-filled radiator (2,500W)94.4°F (34.7°C)Feels warm
Space heater cord temperature measured with a Bosch laser thermometer

As you can see, the cord of my oil-filled radiator space heater gets significantly hotter than the infrared heater’s cord.

But none of them is hot.

Why do space heater cords get hot?

In the experiment above, I showed that some space heater cords get hot while others don’t.

For the measurements, I used one 800W space heater and one 2,500W space heater.

The more powerful 2,500W space heater’s cord is warmer than the weak space heater’s cord.

Electric current heats up the power cord

Too much electricity in a power cord causes heat buildup. Electrons charge from your wall outlet to the space heater’s heating elements, passing through the metal wire inside your power cord.

The more current your space heater draws from the wall outlet, the more electrons flow, and the more these electrons bump into the wire’s metal atoms, shaking them around and creating heat.

A typical American 1,500W space heater draws 12.5 Amps from a 120V US wall outlet. That’s a lot for a regular power cord and, therefore, heat buildup is normal.

As you can see in the experiment table, the stronger a space heater is, the hotter the power cord gets.

space heater power cord temperature measurement oil-filled radiator
Measurement of the 2,500W heater power cord temperature: 94.4°F

Heat coming from the space heater heats the power cord

While measuring my space heaters’ temperatures, I noticed one interesting thing.

The infrared heater’s cord temperature was very low. One explanation is the lower wattage of that particular heater model.

However, another reason the cord did not heat up as much is the directional heat of infrared heaters.

Infrared heaters emit most of their heat as infrared heat and a small part of their heat through convection (hot air rising from the heater).

None of the heat from the infrared heater radiates toward the power cord.

On the other hand, the oil-filled radiator’s cord gets a lot warmer. But the higher power consumption (2,500W vs. 800W) is not the only explanation.

I noticed parts of the cord getting warm, simply because the oil-filled radiator also radiates heat toward the power cord.

The black power cord absorbs a lot of the heat and heats up.

To make sure the oil-filled radiator’s heat is not the only reason for the cord heating up, I measured the temperature across the power cord.

The cord was warm everywhere, which explains the heat up due to the electric current.

But the closer I measured to the heater, the hotter it got.

Space heater power cords can also get hot because the heater radiates heat directly at the cord. Large currents passing through the cord and external heat exposure add up.

Is my space heater power cord getting hot safe?

If your space heater meets your wall outlet’s power specification, your space heater power cord getting hot is safe and expected.

In the measurements performed earlier, I can guarantee that the wall outlet specs fulfill the space heater’s power requirement.

So, a space heater cord getting warm is expected.

Large currents will always heat a power cord. And external heat exposure from the space heater radiating a part of its heat at the power cord is expected as well.


A space heater power cord getting warm is normal. But overheating is not expected and is always unsafe.

Safety checks for a space heater cord getting too hot

Your space heater’s power cord has to fulfill all of the following tests. If it passes each test, you can safely continue to use your space heater.

1. Body temperature check:

Follow this rule of thumb:

Your space heater’s power cord should never be hotter than your armpit (which is about body temperature).

Body temperature is a good reference since it roughly matches the temperature of the strong 2,500W space heater’s cord from the experiment performed earlier.

2. Heat fading away after turning space heater off check:

Turn your space heater off, but leave it plugged into the wall outlet. If the power cord remains hot, the space heater is drawing power from the wall outlet.

This indicates a short circuit or a broken part in the space heater’s internal electronics.

If the power cord remains hot after turning the space heater off, unplug it immediately and get a new space heater.

3. Wall outlet heat up & discoloring check:

White power cords discolor over time. Here’s one simple question to ask yourself:

“Is your space heater power cord turning brown?”

If yes, then your space heater cord is getting too hot. Either the cord is bad quality, or due to an electric fault, it carries too much current.

Please note:

Discoloring can also occur due to light exposure (UV, sunlight) or due to regular material aging. Another factor that supports cord discoloring is indoor air pollution and household chemicals.

In this case, however, the power cord usually doesn’t turn brown. Rather, it gets a beige-to-yellow tint.

How to fix a Space Heater cord getting hot

A space heater cord getting too hot is usually straightforward to fix if you have soldering skills.

If you don’t have the skills and tools to solder, skip to the next section!

First of all, you should get a heavy-duty extension cord. I recommend getting this Clear Power heavy-duty extension cord (click here to view it on amazon).

  • Disassemble your space heater: First, open the space heater’s side where the power cord connects to.
  • Locate the cord’s attachment, and desolder the old wires.
  • Cut the female end off the heavy-duty cord & strip the ends of the wires.
  • Solder the new extension cord in place.
  • Reassemble your space heater.

Replacing the space heater’s original power cord with a heavy-duty extension cord fixes overheating due to poor cord quality.

However, it will not fix your cord overheating due to electronic issues. So, if the issue persists after the cord replacement, I recommend the following:

What to do if you can’t fix your space heater cord getting hot

If you can’t fix your space heater cord getting hot, I recommend getting a new heater.

The safety risk of running a potentially faulty space heater is just too high.

Of course, you can also get your faulty space heater fixed. But this is both expensive, and, if something ever goes wrong and the fixed heater starts a fire, you’ll get problems with your insurance. They don’t like fixed space heaters.

Luckily, there are hundreds of safe and affordable space heaters on the market.

My personal recommendation is this DeLonghi oil-filled radiator (click here to view it on amazon)

It comes with many built-in safety features, including overheat protection.

Also, DeLonghi oil-filled radiators last a very long time. Potentially decades. So, you don’t have to worry about buying replacement space heaters ever again.


A warm power cord on a space heater is a common occurrence, especially for units with a higher wattage (1,200 Watts and more).

However, it’s crucial to distinguish between a cord that’s merely warm and one that’s dangerously overheating.

Armed with the knowledge from this guide, you’re well-prepared to make that call.

Here’s a quick recap:

  • Expect Some Heat: A little warmth in the cord, especially if you’re using a high-wattage heater, is to be expected due to the flow of electric current and potential heat radiation from the heater itself.
  • Check for Danger Signs: If your cord exceeds body temperature, becomes discolored, or doesn’t cool down shortly after turning off the heater, these could be red flags.
    Discoloration, especially if it turns brown or black, can be due to excessive heat or, in some cases, household chemicals. A wall outlet that heats up or discolors is also a concerning sign.
  • Fixing the Issue: Using a heavy-duty extension cord or replacing the existing cord are viable options.
  • Get a new heater: If you’re not comfortable with soldering or working with electronics, just get a new space heater.
    This is the easiest way to be 100% safe.

I hope I could lift the worries off your shoulder with this article. If you have any further questions, just contact me [email protected] and I’ll be glad to help out.