I have a Midwest 50A GFCI disconnect panel supplied by spa dealer. Using #6 wire and 3/4" PVC conduit. The supplied panel has a 3" round hole in the top with a square cover attached by 4 screws. On the bottom of the panel are knockouts. I would like to supply power to the box from the top since conduit exits the house from above, and then run conduit out the bottom to supply power to tub. Can anyone tell me what the hole in the top of the box is for, and can I just drill a hole with my step drill in the cover and use connector ? I really don't want to use flex to curl around and under the box into knockouts to supply the disconnect.