All You Need to Know About: Extension Cords

An extension cord is a group of insulated wires bound together. It functions to provide power from electrical outlets to devices. Since electricity flows through the wires, heat is generated. The wires can be damaged if the current flowing through them is higher than what it can handle. This is why using the appropriate extension cord to meet required needs is very important in preventing shortages that could eventually lead to fire outbreaks.

It is also important to have some basic knowledge of the extension cords. At LifeSupplyUSA.com, you will find high-quality extensions that can be used for indoor and outdoor purposes.

This article takes a detailed look at the basic things you should know about extension cords. Read on.

What Do the Letter Indications on Extension Cords Mean?

Most extension cords come with letter indications that let you know what the cord should be used for. These letter indications include the following:

  • W: These types of cords are perfect for outdoor usage.
  • S: These cords are suitable for indoor usage and general use.
  • J: This indicates that the insulation of the cord is the standard 300-volts. If this letter is not on the cord, it implies that the cord's insulation is 600-volts and meant heavier usage.
  • T: This implies that the cord jacket is made with a vinyl thermoplastic material.
  • P: This means that it is a household cord, and its wire construction is parallel
  • O: This implies that your cord has oil-resistance.
  • E: This indicates that the cord jacket is made with thermoplastic elastomer rubber.


How to Determine the Current Carrying Capacity of an Extension Cord?

There are different lengths, types, and sizes of extension cords on the LifeSupplyUSA online store.

When determining the current-carrying capacity, there are two important factors that must be put into consideration. They include:

Wire Gauge

Wire gauge refers to the wire's diameter, which directly affects its current carrying capacity. The smaller the gauge number, the larger the diameter and the higher the amount of current it can carry. So thicker extension cords carry higher current.


The length of a cord contributes to how high or low the voltage is lost in transition through electrical resistance in the wires.

Shorter extension cords are capable of handling more current than longer extension cords with the same gauge. The shorter the extension cord, the better the electrical current gets.

Types of Extension Cords:

Extension cords are usually available either in a two-prong plug or a three-prong plug. One of the prongs is "live," the second one is "neutral," while for a plug with a third prong, the third one "ground." The ground prong reduces any risk of fires or shock as it provides an avenue for the cord to disperse any power surge into the earth.

Light-Duty Extension Cords

These extension cords on LifeSupplyUSA have a low current carrying capacity. Avoid using these types of extension cords with devices that require high electrical load like heaters, iron. They should only be used with light-duty appliances. Light-duty extension cords do not usually have a ground prong. Instead, they have two plug prongs and should not be used with devices that require a three-prong cord. The ampere rating of this type of extension cord is between 1 to 13 amperes.

Medium-Duty Extension Cords

The current carrying capacity of this type of extension cord on LifeSupplyUSA is higher than that of light-duty. They usually have a third plug prong for grounding and can be used with appliances that require a three-prong cord. In addition, these types of cords are used with appliances like a computer, lawnmowers, power drills, and televisions. The ampere rating of this extension cord type is between 14 to 15 amperes.

Heavy-Duty Extension Cords

You will find a lot of heavy-duty cords on LifeSupplyUSA.com. These cords have the highest current-carrying capacity. Like the medium-duty extension cords, they have a third plug grounding prong and can be used with appliances requiring a three-prong cord. This type of cord's ampere rating is between 16 to 20 amperes, and they are suitable for appliances like power saws, air compressors, and space heaters.

Things to Know When Using an Extension Cord:

Extension cords should not be loaded above their ampere ratings. The ampere rating of the cord can also be read from its gauge size. A 16-gauge extension cord is suitable for light-duty applications. A 14-gauge extension cord is suitable for medium-duty applications. Gauge sizes of 12 to 10 are suitable for heavy-duty and extra heavy-duty applications.

Follow These Tips...

  • Never attempt to remove the ground prong of a three-prong extension cord to use it with a two-prong outlet. This could lead to damaged devices.
  • Indoor extension cords should not be used outdoors.
  • Do not plug multiple extension cords together.
  • Stop using an extension cord if it already feels too hot.



From the letter indications that tell where an extension cord is suitable to the wire gauge, length, and ampere ratings, it can be seen that if not properly understood, extension cords can be hazardous. Extension cords from LifeSupplyUSA are made of high-quality materials and must not be used for the wrong purpose. If you need to choose an extension cord in the future, you can bookmark this article to reference later.

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