It goes without saying that gauge selection is of prime importance for extension cords. The gauge defines the capacity of the cord to accept electrical current safely. Knowing the gauge size may prevent circuit overloading or creating unsafe conditions.

If you ever want to know about extension cord gauges and gauge numbers, this article will cover what each size means and what each is used for.

When planning to use extension cords indoors or outdoors, the safety of extension cords begins with selecting the right gauge. Should you use a 16-gauge cord, or is an 18-gauge cord more suitable? Let’s get started.

Extension Cord Reference Guide

It is important to review the basic terms required to choose the right extension power cords before discussing the classification and types of extension cords.

Ampere (Amp):

The unit for measuring electric current. It means the quantity of electricity that is passing through a wire. An extension cord has ratings regarding the highest amperage, which one can safely run through.

Wattage (Watts):

This basically refers to the power output of consumed amperage electric appliances or gadgets. To obtain wattage, multiply the amperage (Amps) by the voltage (Volts).

Voltage (Volts):

Voltage signifies the electrical force propelling the current through the wire.

Types of Extension Cords

Different extension cords are available, each designed for specific purposes and settings. Here's a look at some common types:

Indoor Extension Cords:

For general indoor use only, these cords are best for the service and not likely to do well when used outdoors because they lack weatherproof features. In most cases, they come in a very thin gauge, which makes them very light and flexible.

Outdoor Extension Cords:

Outdoor extension cords are designed to withstand the elements of the outdoors, such as rain, snow, and sunlight. They contain thicker insulation and rugged outer jackets to resist moisture, while they also include factors that cause physical damage. They also come rated at higher electrical loads than indoor cords.

Heavy-Duty Extension Cords:

These are used in power, heavy tools, industrial machinery, and appliances. They are constructed with a thicker gauge wire and rugged construction to resist rough use in harsh conditions.

Light-Duty Extension Cords:

These are meant for light loads like lamps, small appliances, electronic items, etc. They use thinner gauge wire and hence may not be rugged as in the case of heavy-duty cords. They are cheaper and more apt for occasional use at residential places.

Multi-Outlet Extension Cords:

They have more than one outlet along their length. They allow various appliances to be used from one source and are useful for a garage or workshop and some other places outdoors.

Specialty Extension Cords:

There are cords designed for specific needs, including:

Flat Extension Cords:

The slim, compact design easily hides underneath a carpet or rug, making them ideal for an aesthetic-conscious environment, such as a home or office.

RV Extension Cords:

Tailored for use with recreational vehicles, such often have some sort of connection lock and include weatherproofing against outdoor elements.

Generator Extension Cords:

These are designed in a way that they get connected between portable generators and appliances or power panels. The key features include alligator clips or NEMA connectors at one end and the other with heavy-duty, built to be as powerful as the generators.

Specialized Extension Cords:

There are cords for specific applications, such as:

Air Conditioner Extension Cords:

They deal with a heavy electrical load, which is a thermostat-controlled air conditioner, and hence, they often come with in-built surge protections.

Welding Extension Cords:

These are tailor-made for welding equipment and can support high currents that occur when one is doing a welding job.

The choice of extension cord for this matter should be due to the kind of work it will be put to, the electrical load of the appliances tojsonified, the length of cord required, and whether it is to be used inside a building or outside. Incorrect extension cord usage is potentially dangerous. It may even lead to device damage or cause electric shock or fire. Always heed the manufacturer's instructions before use.

How to Choose the Right Extension Cord

extension power cords

The choice of the extension cord always ensures the right choice concerning safety and efficiency that allows for the connection of electrical appliances and tools. Below is a detailed guideline that could help a user in choosing the correct extension cord:

Consider the Wattage/Voltage Requirements:

You should consider the wattage or voltage the appliance or equipment you use over the extension cord requires to run. This information will usually be on the appliance's label or instruction manual. Ensure the extension cord can handle the power load without overheating or causing damage.

Check Cord Gauge and Amp Rating:

The extension cord has a gauge or AWG, which explains how much electrical current it can carry. The lower gauge number represents thicker wires and higher ampacity. For instance, gauges 12 or 14 are smaller, so they are considered appropriate for heavy-duty appliances or power tools, while on the other hand, large gauges should be considered 16 or 18; they are better adapted for lighter loads, such as lamps or electronics. Ensure that the cord's amp rating matches or exceeds the requirements of your devices.

Length of the Cord:

Based on your needs, choose the appropriate length of the extension cord. The longer the cord, the more resistance, especially with a heavy load on the line, and the voltage will fall off with distance. The further the devices are being powered from the outlet, the shorter and thicker the cord should be used so as not to get a dangerous drop in voltage.

Indoor vs. Outdoor Use:

Some extension cords are designed for indoor or outdoor use only, while others are rated for both. Outdoor power extension cords are more durable, have reinforced jackets, and have water-resistant connectors; hence, they are best for use outside. An indoor cord may not withstand moisture and harsh weather conditions.

Jacket Material:

The jacket materials of the extension cords vary; they can be rubber, vinyl, or even thermoplastic. Vinyl cords are affordable and properly serve any application, be it at home from light to medium. Rubber jackets are generally flexible and heavy-duty, therefore suitable for use and applications outside.

Safety Features:

Find out if extension cords do have any of the safety features such as grounded plugs, polarized plugs, or GFCI (Ground Fault Circuit Interrupter) protection. The three-prong grounded plug allows a path for excess electrical current to safely dissipate. Polarized plugs are made such that one blade is bigger than the other, ensuring correct polarity when plugged in. Therefore, these should be available in outdoor or wet locations to eliminate electric shock.

Consider Specialized Needs:

For special needs, such as using extension cords in the workshops and construction sites, abrasion-resistant, oil-resistant, or high-visibility jackets for security.

Check for Certification:

Ensure that the extension cord conforms to safety standards and has the certification of an organization like Underwriters Laboratories (UL) or Intertek (ETL). Look for marks or labels that say the cord has met safety standards.

Avoid Overloading:

Never put too much burden on any extension cord. This means that you should not plug in more appliances or devices collectively, which add up to an amp rating more than the extension cord. Very likely, overloading means you are risking overheating, melting insulation, and even the possibility of electric fires. Use power strips or multiple extension cords to share the load.


1. How long of an extension cord can I safely use?

Extension cord length should be chosen based on the power requirements of your devices and the cord's gauge. Generally, for lower-power appliances, you can safely use longer cords, but for higher-power devices, shorter cords are recommended to prevent voltage drop.

2. Can I use extension cords outdoors?

Yes, but ensure you're using outdoor-rated cords to withstand weather conditions. Keep them protected from water and other elements, and avoid running them through standing water or burying them underground.

3. Is it safe to daisy-chain extension cords?

It's not recommended for daisy-chain extension cords, as it can lead to overloading and fire hazards. Instead, use a single, appropriately sized cord for each device or use a power strip with a built-in circuit breaker for multiple devices.