Proper free vent areas is an assumption I wouldn't make. It's rare to have enough & without it the fan will fight the back-pressure. It will also force attic dust into the house, a real problem with allergies.
I tie a whole house fan in with a couple power roof vent fans. It cools the attic & house quickly. I did one a few weeks ago on the lighting circuit with no problems. The motors were all small.
