Extension Cord Gauge

When choosing an extension cord to use with an electrical appliance like a power tool, you need to make sure the extension cord you want to use will deliver enough amperage to run the appliance safely. To find out how much amperage the appliance needs, you can look on the label affixed to the appliance or check the appliance’s owners manual. Next, measure the length of the extension cord in feet. With these two numbers, you can use a chart like the one in our “What Size Extension Cord Do I Need?” article to determine what size the wire inside your extension cord needs to be for safe operation. So now we need to answer the question “What Gauge Is My Extension Cord?”

On every extension cord, the size of the wire used in the extension cord (measured in the wire’s gauge and commonly referenced as “AWG”) is stamped on or moulded into the body of the extension cord itself. However, these gauge numbers can be difficult to find.

Finding the gauge of an extension cord

In the picture above, the wire’s gauge is stamped on the extension cord as “12/3”. The “12” is the wire’s gauge and the “3” is the number of wires (hot, neutral and ground) in the extension cord. So here we have a 12 gauge extension cord.

Moulded Wire Gauge

In the other picture, the wire’s gauge is moulded into the extension cord itself. As you can see, these can be very difficult to find unless you have the proper lighting, not to mention a magnifying glass. Here, both of these extension cords use 16 gauge wire. On the top cable, you can barely see “16AWG”. On the other cable, you see “AWG16x2C”. Both signify that the wire used inside each extension cord is 16 gauge. Like in the first picture, the “2C” means that the extension cord pictured has two wires.

Helpful Hint: If you have an extension cord that doesn’t have the wire’s gauge clearly marked, throw it way! Any extension cord that doesn’t let you know how it was constructed is of questionable quality and should not be used.

Now that you can find the size of the wires used in your extension cord, use the chart in our “What Size Extension Cord Do I Need?” article to determine how many amps the extension cord can safely deliver. Now wrap a piece of tape around the extension cord and use a permanent marker to label the extension cord with the amperage rating so you don’t have to repeat all of this in the future.