What is the maximum safe length for a 16-gauge extension cord at 10 amps?

Stick to 50 feet for reliable performance. You can push to 100 feet in a pinch, but you’ll lose noticeable power and risk overheating the cord due to voltage drop. At 100 feet, the 5% voltage drop can make motors run hotter and slower, and coiling the cord can cause dangerous heat buildup. If you need 100 feet, step up to 14-gauge.