Flat extension cords vs round extension cords: Round wins for heavy-duty use, flat is for light indoor duty

Flat cords are cheap and flexible for low-wattage stuff like lamps, but they’re prone to pinching and overheating over 10 amps. Round cords have thicker insulation, better crush resistance, and handle higher amperage for saws or space heaters. Don’t use a flat cord for anything that draws real power—that’s how garage fires start.