Choosing The Correct Extension Cord

By Robert Robillard on Workshop tips

Choosing The Correct Extension Cord

How To Choose The Correct Extension Cord

Choosing the correct extension cord is important to tool and job-site safety.

Power tool requirements vary for different tool applications. Using the wrong extension cord can cause hidden damage to a tool or even worse -create a fire hazard.  When choosing the correct extension cord look for cords with at least have a rating equal to or greater to the requirements needed to run a tool effectively.

Extension cords differ in the number and thickness of the wires, the type of plug, and the length of the cord.

Wire thickness:

Extension cord wire thickness determines the amount of power that will be delivered to the tool. Common sizes, or gauges, which are 18, 16, 14, 12 and 10.

Extension cords vary in rating based upon the amperage it can carry, the wattage it can handle, and the gauge of the wire. The smaller the number of wire gauge, the more wattage and amperage it can handle safely.

I use 12 gauge extension cords and keep several lengths of 25′, 50′ and one 100′ cord in my tool trailer.

Length of the cord:

Extension cord length can cause problems. Don’t use a cord that is far longer than what you need, especially if you leave the excess cord coiled. Leaving an extension cord coiled causes heat to build up in the wires which can get hot enough to melt the insulation.

Type of plug:

I recommend always use a three prong, grounded extension cord.

Extension cord lengths 50 feet or less can be used based upon the following chart, but runs over 50 feet should implement the next heavier sized cord to accommodate voltage drop in the cord due to the natural resistance of the wire.

  • #18 gauge cord: 5 Amps, 600 Watts: Detail Sander, Drill, Jig Saw
  • #16 gauge cord: 7 Amps 840 Watts: Belt Sander, Reciprocating Saw
  • #14 gauge cord: 12 Amps 1,440 Watts: Circular Saw, Miter Saw,
  • Router
  • #12 gauge cord: 16 Amps 1,920 Watts Table Saw, Radial Arm Saw
See my post on Extension cord safety.
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Robert Robillard

Carpenter / Remodeler / Editor

Rob Robillard is “The Concord Carpenter” Rob is a builder, general contractor, carpenter, woodworker, and editor of Concord Carpenter and ToolBoxBuzzr As a General Contractor and carpenter, Rob owns and operates Concord Carpenter LLC. A full-service remodeling and construction company. Rob is a recognized leader in home building best practices and a source for how-to information for building professionals. On this website, Rob covers all aspects of home construction, building science, home improvement, woodworking, remodeling, and some of the best product and tool reviews. Rob is in charge of our Tool and Product Review series - Concord Carpenter Videos where we post all of our tool reviews and video tutorials. Rob approaches remodeling and building construction with a pragmatic and problem-solving approach. He enjoys using his knowledge and experience to help and educate building professionals as well as DIYers on best practices in the construction and remodeling industry. He's a strong advocate for "raising-the-bar" in the construction trades and promoting the trades to youth. #BeAMentor #Green2Great Craftsmanship, quality, and pride guide his journey on this channel The Concord Carpenter's motto: "Well done is better than well said!" : Read more about Rob

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