Power Tool Extension Cord Ratings

Extension Cord

Not all extension cords are created equal, especially when it comes to power tools. Using the wrong cord can cause your tools to underperform, overheat, or even become dangerous. This guide covers how extension cords are rated, how to match them to your tools, and what to avoid on the jobsite or in your garage.

Key Extension Cord Ratings Explained

Gauge (AWG – American Wire Gauge)

The lower the number, the thicker the wire and the more power it can handle.

  • 14-gauge – Light-duty; short cords up to 25 ft
  • 12-gauge – Standard for most power tools up to 50 ft
  • 10-gauge – Heavy-duty tools, long distances (50+ ft)

Rule of Thumb: If your tool draws 10+ amps, don’t use anything thinner than 12-gauge.

Amperage Rating

Cords are labeled with max amperage. Match or exceed your tool’s amp draw.

  • Look on the tool label (usually near the handle or plug)
  • Never use a 10-amp cord for a 13-amp tool

Length Affects Power

Longer cords = more resistance = more voltage drop

  • 25 ft: Most cords will be fine for medium-duty use
  • 50 ft: Use 12-gauge or better
  • 100 ft: Only use 10-gauge or heavy-duty commercial cords

Long cords with small gauge = heat buildup and reduced tool performance.

Recommended Gauge for Tool Amps (Up to 100 ft)

Tool Amps

25 ft

50 ft

100 ft

0–6 A

16 AWG

16 AWG

14 AWG

6–10 A

16 AWG

14 AWG

12 AWG

10–13 A

14 AWG

12 AWG

10 AWG

13–15 A

12 AWG

10 AWG

10 AWG

Understanding Cord Markings

Extension cords are often labeled with a string like this: SJTW 12/3 125V 15A

Here’s what it means:

  • S = Service grade (portable)
  • J = Junior service (rated to 300V)
  • T = Thermoplastic insulation
  • W = Weather-rated for outdoor use
  • 12/3 = 12-gauge wire, 3 conductors
  • 15A = Maximum amperage

For jobsite tools, always choose cords with a “W” for outdoor/weather durability.

Cord Maintenance and Storage Tips

  • Coil Loosely – Avoid tight wrapping that stresses internal wires
  • Never Pull by the Cord – Always pull from the plug to avoid fraying
  • Keep Dry – Store off the floor in a clean, dry area
  • Inspect Regularly – Replace cracked, frayed, or stiff cords
  • Label Gauges – Use tags or color-coded ties to identify gauge and length easily

Final Thoughts

Choosing the right extension cord for your power tools isn’t just about convenience, it’s about performance and safety. Using an underrated or overly long cord can cause tool failure, overheating, or even fire. Stick to the right gauge, know your amp draw, and treat your cords like you treat your tools, with respect.