Update for future reference, to anyone who might need it in the future:
The key to make sure the wiring is safe is the amperage. The fan will state what amp it requires, either on the box or in the instructions. In my case the 6" duct fan from home depot needed a 15 amp cord. I wandered over to the extension cords, and they had pre-cut extension cords designed for power tools and this purpose. They were exactly 15 amps. There were plenty of extension cords that did not have the third, grounding prong, and plenty of cords that were not 15 amps. As long as you make sure to get the correct cord it couldn't have been easier, the wires were color coded exactly as the fan.
My thanks to the original poster. Using a 4" fan for intake and the 6" fan for outtake I am able to use a 400 watt halide in a space less than 30 cubic feet without heat issues!
The key to make sure the wiring is safe is the amperage. The fan will state what amp it requires, either on the box or in the instructions. In my case the 6" duct fan from home depot needed a 15 amp cord. I wandered over to the extension cords, and they had pre-cut extension cords designed for power tools and this purpose. They were exactly 15 amps. There were plenty of extension cords that did not have the third, grounding prong, and plenty of cords that were not 15 amps. As long as you make sure to get the correct cord it couldn't have been easier, the wires were color coded exactly as the fan.
My thanks to the original poster. Using a 4" fan for intake and the 6" fan for outtake I am able to use a 400 watt halide in a space less than 30 cubic feet without heat issues!