What extension cord should I use for a high-amperage tool like a pressure washer?

For a 15-amp tool, use a 12-gauge or thicker cord under 100 feet. Longer runs need 10-gauge. Avoid light-duty or indoor cords—get one rated for outdoor use (marked “W” or “WA”). Thinner or longer cords cause voltage drop, making your tool struggle, overheat, or trip breakers.