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Which Extension Cord Is Good for Air Conditioners? (What To Look For)

extension cord for air conditioner

You finally plugged in your window AC unit to combat the summer heat and you realize the cord isn’t long enough. Before throwing the AC out of the window in frustration, read this article. We’re going to find an extension cord that gets rid of this headache. Keep in mind, not just any extension cord is safe to use in this situation.

The Problem with Undersized Extension Cords

If you use an undersized extension cord, you could be signing yourself up for trouble. Undersized extension cords are widely marked as the leading cause of fire and death in a home. An AC unit won’t keep you cool during a fire, so be very careful and read this list before plugging in a cord.

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Replacing the Original Cord VS Using an Extension Cord

The best alternative to using an extension cord is replacing the cord in the air conditioner. The manufacturer will allow you to replace the original cord as long as the outlet is less than 10 feet away from the unit. In this case, you won’t have to worry about overloading an extension cord or finding the right option. If this isn’t an option, keep reading.

Extension Cord Size Matters

When it comes to extension cords, size matters. If you didn’t know, every cord has a certain wire gauge. The wire gauge determines how much current can be handled by the extension cord.

Too much current on an undersized cord will lead to overheating and an eventual fire. The problem with AC units is that they draw more current when they start up. Even if the standard operating current is met by your extension cord, you might still have an undersized cord for when the unit starts operating.

How To Find What Size Extension Cord To Use With Your AC Unit

You should start by finding out the power consumption of your AC unit. There should be a label on the unit that has all the science-y numbers. You’re looking for wattage in this case.

A lot of air conditioners will fall between 900 and 1,500 watts. You can use this value to find out what size extension cord you need.

Extension cords are rated in terms of amps that they can handle. You might wonder why you care about watts, then. Well, you can convert from watts to amps with a little math.

Check the label on your AC unit again and find the rated voltage. A lot of units use 120 volts.

Now, take your rated watts and divide by your rated voltage to get how many amps you’ll need. If your unit is rated at 1,000 watts and 120 volts, you will need an extension cord that can handle 8.4 amps.

You can find the rated amperage on the label of the extension cords you’re thinking about using. As long as the rated value is higher than the number you need, then you’ll be okay.

Understanding Wire Gauge

So now it’s time to find an extension cord with the right wire gauge. As the gauge number gets lower, the wire can handle a higher amperage.

On the lowest side, a 2-gauge wire can carry up to 95 amps. Of course, that’s way outside of the scope of things here.

For you, you’ll probably be deciding between a 14-gauge and 12-gauge wire. A 14-gauge wire can carry up to 15 amps, and a 12-gauge wire is rated up to 20 amps.

In many cases, it’s wiser to go with a 12-gauge wire. Remember that the voltage in your home will fluctuate over time. You won’t get exactly 120 volts 24/7. On top of that, your unit will draw more amps when it first starts, so you want to have a healthy margin on top of what you need.

Here’s an article I wrote explaining how to find what gauge your extension cord is.

Where to Buy Extension Cords For Air Conditioners

Your favorite hardware store or online retailer should carry the right extension cord for you. Just as long as it’s rated for the right amperage, you won’t have a problem.

If getting to a store isn’t as convenient as ordering online, there are plenty of online stores that sell extension cords capable of handling the power needs of your air conditioner, such as Amazon or Home Depot. Below is the extension cord I use at my house. I bought it from Amazon.

Great For Refrigerators!
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11/27/2021 10:46 am GMT

Additional Considerations

There are a few other things to consider before buying an extension cord and having it shipped over. Let’s talk about them.

Extension Cord Length

You always want to select the shortest cable possible. Ideally, the cord will be just long enough to hug the wall from the unit to the outlet.

Longer cords lead to more problems and are susceptible to damage (which will be discussed later). In the case of buying an extension cord for your air condition unit, less is more.

Total Number of Prongs

All AC units have a three-prong plug. This means that they include a ground in case the unit gets shorted. You want to make sure that your extension cord has a three-prong plug as well as an outlet.

If the cord only has a two-prong plug but a three-prong inlet, then you can’t use it. It will lead to big trouble in the future.


Every cord comes with a different level of durability. You want an extension cord that’s thick, strong, and resilient. This is an area where it’s preferred that you go for the more expensive option.

You don’t want a faulty extension cord to ruin your AC unit. Realistically, this cord should last as long as you expect to use the ac unit which could be years.

Angled Plug

If you can find an option of a vertically angled plug, you should opt for that. With the plug closer to the wall there is less room for error. You won’t accidentally bump into the plug and unplug the unit or bend the connection point.

This is especially useful if you’re going to run the cord along the wall.

How to Prevent Damage to an Extension Cord

When you’re running an extension cord from your AC unit to your outlet, you need to hug the wall as much as possible. You might find the best results if you staple the cord to the top of the baseboard rather than letting it run along the floor.

Pets, people, and vacuums will run into this cord and might damage the cable or rip the plug from the wall. For something long-term like this solution, you want to make sure it’s functional and looks neat, too.

Some homeowners will drop the cord straight down from the unit, then make a 90 degree turn, follow the top of the baseboard, then make a 90 degree turn upwards directly to the outlet. Using staples along the way will ensure the cord doesn’t droop or get stuck on anything.

This method looks neat and preserves the cord for as long as possible. If the unit is in a room that guests will see, then it’s always best to make the cord look as presentable as possible.

Final Tips and Thoughts

Finally, let’s talk about some tips and thoughts to see the best results while using an extension cord for your AC unit.

  • Don’t run the cord under a carpet. The cord might heat up and start a fire.
  • Leave the cord uncovered at all times for the same reason.
  • Use a dedicated outlet that doesn’t have anything else plugged in. This will preserve your cord for longer and reduce the potential for error.
  • Use tape for a less aesthetic alternative of securing the extension cord run. This is preferred for people who are renting their home or apartment and can’t make holes in the wall.
  • If you notice your cord is fraying, immediately unplug it and replace it as soon as possible.
  • If the distance is too great, you might want to bring in an electrician to add a new outlet or relocate a nearby outlet.
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