Re: Entering the top of a W.P. box
I agree with Tom Baker about using a Myers-Hub when you are trying to keep equipment water-proof.
Let me give you an example of how we would keep water out of our equipment coming into a junction box. We would bring the conduit down to the side of the box, and install a condulet tee. We then would go into the box at the bottom of the box and also at the bottom of the tee, we would install a listed drain fitting to drain any water that might get into your conduit system. Having worked in one of the largest Waste Water Treatment plants in the country, we found that this was a good way of keeping water out of our electrical equipment. I wish that I could show this arrangement with a picture, then it would be easier to understand.