Don't coil an extension cord while it's under load.

Yes, coiling an extension cord while it’s drawing current can cause dangerous overheating. It’s not just internet lore — it’s physics. Heat builds up in the center of the coil because air can’t circulate, and the wire’s resistance turns that trapped heat into a fire risk. You want the entire cord loose, not twisted or wound tight.

How much slack? Ideally, unspool the whole cord. If you can’t, leave at least a few feet between loops — think loosely draped, not stacked in a pile. A cord reel designed for continuous use (the kind with a built-in thermal switch) is the only exception, but even then, don’t fully reel it in while it’s running.

If you’re tempted to just leave it coiled “for a minute” while you run a shop vac or heater — don’t. Uncoil it. Future You deserves a house that isn’t on fire.