5 Things to Know About Extension Cord Length and Wire Gauge

Longer cords need thicker wire Every foot of extension cord adds resistance, causing voltage drop and heat. The longer the cord, the less current you can safely draw at the same wire gauge.

Keep voltage drop under 3% for 120V tools That means no more than about 3.6V lost. Exceeding this makes tools run slower and motors run hotter.

Match gauge to length for 15-amp loads At 50 feet, 14-gauge is fine. At 100 feet, use 12-gauge. At 150 feet, step up to 10-gauge.

For 20-amp loads, double the gauge Use 12-gauge at 50 feet, 10-gauge at 100 feet, and 8-gauge at 150 feet.

Never coil a long cord under load The heat can’t escape and will melt the insulation. Buy the right gauge for the length you actually need.