Either should work. However, most plugs readily available are polarized. If you plug it into a wall you will be ok with one. If you are plugging it into the light/motor junction box, you will find one blade won't go in. What I do with that may make an electrician cringe so proceed at your own risk. I just grind down the blade of the new prong to the right shape before I even connect it to the wires. My theory is that these guys were made before polarized plugs and probably don't need them. I would love to hear someone more knowledgeable than me give you an answer.