How to Make a Heavy Duty Extension Cord

Basic household extension cords are made with wires that will support a standard 20 amp flow.

Heavier extension cords for the shop or garage can be found that will support a 30 to 40 amp flow rate. Heavier cords than that are generally made for the commercial market, and may be difficult to obtain. However, if you are a solid do-it-yourself person, you will be able to make your own heavy duty extension cord that will work as good as anything else made for home or business.

Romex can be purchased at any hardware in spools. Decide on how much amperage you need, the length you want and the desired gauge.

Cut your Romex to your desired length with your wire cutters.

Use your wire strippers and strip about one inch off the protruding wires.

Unscrew the male plug body and pull it apart to reveal the wire attachment pegs.

Unscrew each flat bladed screw on the pegs with your screwdriver. Two pegs are attached to the electrical plugs, and one peg is attached to a the center grounding plug.

The two pegs that turn into plugs will get one white wire and one black wire. Attach them firmly by looping the wires over the screw threads and tightening them in.

The center plug is where the green wire will be attached too. Attach it firmly by looping the wire over the screw threads and tightening them in.

Reconnect the male plug body and one side is finished.

Unscrew the female plug body. The wire attachment pegs will turn into plug receptacles.

The left and the right receptacle will be wired with both a white and a black wire. Attach them firmly by looping the wires over the screw threads and tightening them in.

The center receptacle is where the green wire will be attached too. Attach it firmly by looping the wire over the screw threads and tightening them in.

Reconnect the female body, and your heavy duty extension cord is finished.

Things You Will Need

  • Low gauge Romex electrical cord-The lowest, #2 gauge is rated at 95 amps
  • Three wire grounded male plug conforming to your desired amperage rating
  • Three wire grounded female plug conforming to your desired amperage rating
  • Wire cutters/strippers
  • Flat blade screw driver

About the Author

Dale Yalanovsky has been writing professionally since 1978. He has been published in "Woman's Day," "New Home Journal" and on many do-it-yourself websites. He specializes in do-it-yourself projects, household and auto maintenance and property management. Yalanovsky also writes a bimonthly column that provides home improvement advice.