Difference Between Indoor and Outdoor Extension Cords a Definitive Guide

Last Updated on December 4, 2023 by Kyle Whitley

Did you know that there are two types of extension cords? What is the difference between indoor and outdoor extension cord? Whether you’re looking for an outdoor or indoor extension cord, we have the information you need to make an informed purchase. Let’s find out the difference between indoor and outdoor extension cords.

What is an extension cord?

An extension cord is a device that you use to extend the reach of a power outlet. Extension cords are often used when you want to provide power from one outlet but cannot connect it to another.

Extension cords can be used for many different types of devices.  They can be used to power a simple table lamp or can be used to connect a generator to your home.

How do extension cords work?

To transfer the electric current, extension cords use wires that are insulated. The protective insulation is usually made of rubber, vinyl, or plastic.  This is often protective insulation is referred to as the cord jacket.

One end of the extension cord is plugged into an electrical outlet, and the other is plugged into a device that needs power.

Extension Cord Designation Definitions

How do you know if an extension cord is for outdoor use?

The best and easiest way to know is to look for the  TYPE designation on the side of your extension cord.  If the cord is designated with a “W” it is an outdoor rated extension cord.


Indoor vs Outdoor Extension Cord

There are two general types of extension cords.  Indoor extension cords and outdoor extension cords.  Let’s take a look at the differences between each cord type.

What is an indoor extension cord?

Indoor extension cords are mostly used for small appliances, like fans and lamps.   An indoor extension cord doesn’t have a weatherproof covering and has a regular two-pronged plug.
As the name suggests, indoor extension cords are intended for indoor use only.  They do not have the insulation, safety standards, and capacity to run outside or power items such as lawn mowers, leaf blowers, or snow blowers.

Why use an outdoor extension cord?

If you own any outdoor power tools that need a plug to operate, you will need an outdoor extension cord.  You might also have some outdoor lighting that needs power as well, or you might need to run a pump in an outdoor water feature.


You may be wondering why you need to buy an outdoor extension cord. The answer is pretty simple. An extension cord designed for indoor use will not hold up well if you leave it outside. It might actually be unsafe to use an indoor extension cord outside because the indoor extension cord will be affected by the elements much sooner.

You can leave an outdoor extension cord outside because it has a water-resistant covering. The covering will keep the extension cord from being damaged by moisture, which can cause a short. The covering is also UV resistant, keeping the cord from breaking down due to extended time in the sun.

All outdoor extension cords come with a three-pronged plug.  The third prong is used as a ground that will help to protect against fires or electrical shock.


Keeping you safe in wet environments.  If the plugs or outlets you are using aren’t a GFCI (ground fault circuit interrupter), you should use a GFCI adapter between the outdoor plug and the extension cord.
GFCI outlets help protect you by preventing dangerous electric shock. The GFCI can sense a short and act similar to a small circuit breaker.

While it is ok to use an outdoor extension cord indoors, you should never use an indoor extension cord outdoor.

Power Requirements

Tools you might use with an outdoor extension cord pull many more Amps than devices you might use with an indoor extension cord.  Any device that you might be using outside, such as a leaf blower, pressure washer, or snowblower, is definitely going to pull more amps than your average TV or table lamp.

AMPS or amperage is how much power your device will pull. The higher the amperage rating, the more power it will pull. Important note: Each outdoor cord is only rated for a certain amount of amperage.  If you exceed the recommended amps you risk damage to your extension cord and to your tool or appliances.

AWG or the American Wire Gauge rating is used to determine the thickness of the wire used in a cord. The lower the number, the thicker the cable.  The thicker the cable, the more power a cable can handle. For instance, you can have a cord that is a 14/3 extension cord.  This means the cord has a 14 wire gauge and 3 wires inside.

If you use an outdoor extension cord with a device that pulls too much power, you could risk tripping a circuit breaker or, even worse, starting a fire.


Differences between indoor and outdoor extension cords

The main differences between indoor and outdoor cords are the length of the cord, the number of prongs on the cord, cord insulation, and power rating.

  • indoor extension cords are usually 25′ feet or less; outdoor extension cords can reach lengths up to 150 feet
  • indoor extension cords only have two prongs on the power plug; outdoor extension cords have three (two including a ground)
  • indoor extension cords have limited insulation because they are not exposed to water and outdoor elements; outdoor extension cords have varying types of insulation to protect them from water, UV light, and temperature changes
  • indoor extension cords have small AWG/AMP ratings because they provide power for low-power consuming devices; outdoor extension cords have higher AWG/AMP ratings because the devices they power draw higher AMPs and need thicker wire to run safely.

Extension Cord Length

The general recommendation with any extension cord is the shorter, the better.  The longer power has to run through the extension cord, and the more electrical resistance is encountered.

In turn, this limits the amount of power that can be delivered from an extension cord.  For outdoor power equipment, the general rule is not to extend extension cords beyond 100 feet; of course, this depends on the type of device you are trying to power.

In Conclusion: Difference Between Indoor and Outdoor Extension Cords

There are many differences between indoor and outdoor extension cords.   Indoor extension cords are only meant for the indoors. Outdoor extension cords have more capacity and safety standards built into their design and are built to withstand moisture, UV light, and temperature changes.   Keep indoor extension cords indoors and use the proper outdoor extension cord for your outdoor power needs.


Do’s and Dont’s of Extension Cords

How to Tell if an Extension Cord is for Outdoor Use