How to Select an Electrical Extension Cord

  • 01 of 05

    How to Select the Right Electrical Extension Cord for the Job

    Power Cords
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    You've often used an extension cord around the home, but using the wrong type of cord can be dangerous. The U.S. Product Safety Commission found that extension cords are among the most dangerous electrical appliances in our homes because of improper and overloaded power cord usage. Each year, accidents from extension cords kill around 50 people, resulted in injuries requiring hospital treatment to 4,000 others and also cause over 3,000 residential fires.

    Electrical extension cords come in...MORE many types and capacities. The capacity of an electrical extension cord to safely extend power is based on two factors:

    • Gauge: Gauge is a measurement of the thickness/diameter of the wire
    • Length: Length of the extension cord affects voltage drop

    Gauge is how the copper wire is measured and is reported as a number. For example, you may see a No.12 gauge or a No.18 gauge 120-volt extension cord. These numbers are tricky however in that the smaller the number the thicker the wire, and conversely, the larger the number the thinner the wire. So a No. 18 gauge extension cord may only be rated for 5 to 7 amperes of load and a length of up to 25 feet. A No 10 gauge extension cord may be rated for 15 amps of load and 100 feet in length.

    Length of the extension cord affects voltage drop. Voltage drop is ​the result of the friction or resistance the electricity experiences flowing through a long wire. You want to use the shortest extension cord possible. Thought of another way, the longer the extension cord, the thicker (lower gauge number) the wire.

    Let's take a look at the 3 major types of extension cords you'll find and how to safely use them.

    Continue to 2 of 5 below.
  • 02 of 05

    Light Duty Extension Cord Use

    Light duty 10 gauge two wire extension cord.

    For simple extension cord use around the home such as lamps, clocks, and other light duty electrical devices up to 7 amps, use the following table for gauge size and extension cord length. For this light duty use the cord may not have a third wire for ground.

    Cord Length: Up to 25 feet
    Proper Gauge Size: No. 18 Gauge

    Cord Length: Up to 50 feet
    Proper Gauge Size: No. 16 Gauge

    Cord Length: Up to 100 feet
    Proper Gauge Size: No. 14 Gauge

    Continue to 3 of 5 below.
  • 03 of 05

    Medium Duty Extension Cord Use

    Medium duty 14 gauge three wire extension cord.

    For medium extension cord use such as small appliances, laptops and other devices up to 10 amps, use the following table for three-wire grounded extension cord gauge size and extension cord length.

    Cord Length: Up to 25 feet
    Proper Gauge Size: No. 16 Gauge

    Cord Length: Up to 50 feet
    Proper Gauge Size: No. 14 Gauge

    Cord Length: Up to 100 feet
    Proper Gauge Size: No. 12 Gauge

    Continue to 4 of 5 below.
  • 04 of 05

    Heavy Duty Extension Cord Use

    Heavy duty 10 gauge three wire extension cord.

    Heavier duty extension cord use for power tools and larger appliances of 15 to 10 amps require a three wire grounded extension cord. Use the following table for gauge size and extension cord length.

    Cord Length: Up to 25 feet
    Proper Gauge Size: No. 14 Gauge

    Cord Length: Up to 50 feet
    Proper Gauge Size: No. 12 Gauge

    Cord Length: Up to 100 feet
    Proper Gauge Size: No. 10 Gauge

    Continue to 5 of 5 below.
  • 05 of 05

    Trick for Keeping Cords from Separating

    Using an overhand knot to connect extension cords is an easy way to keep them together.

    OK, let's say you want to edge your sidewalk and need a 50-foot extension cord but you only have two 25 foot cords. If you just plug the cords together that's fine, until you pull on the cord slightly and they disconnect.

    To keep them together, use this little trick of an overhand knot as shown in the photo to keep your joined cords together. It's simple and works great.