Clean your box fan or it'll catch fire

A box fan in a dusty barn or workshop can be safe if you keep it clean, but it’s a real fire risk if you let dust build up.

The problem is that box fans have an open motor design with no sealed housing. Dust gets inside, coats the motor windings, and acts as insulation. That means the motor runs hotter, and eventually the thermal fuse blows — or the motor literally catches fire. I’ve seen it happen in a friend’s woodshop. The fan was running fine, then started smoking. He yanked the plug just in time.

Dust also builds up on the blades and grille, causing imbalance and extra strain on the motor. If you’re in a barn with hay dust or a metal shop with conductive metal shavings, that’s even worse. Hay dust is explosive at the right concentration, though that’s more of a theoretical risk with a fan.

If you’re going to run a box fan in a dusty space, do three things: clean the grille and blades weekly (or before every use in heavy dust), mount the fan off the ground so it’s not sucking up floor debris, and never leave it running unattended. Even better, put