Best way?
The arrangement you describe is typical for indoor installations ... but not for outdoor.
Typically, an outdoor unit will have sort of junction box, as there's no way the cables will reach the panel.
"Bargain" installs will attempt to use a box of some sort in the pit. This is a poor choice, as a) the box rusts, and fills with crud; and, b) cables coming in are subject to damage, ensuring a future replacement.
"Better" installs will have a Christy box near the pit, with splices made there. The weakenss with these is that the conduit to the pit is NEVER big enough. Cables swell, and it becomes impossible to pull them out for replacement.
"Best" would be TWO handholes - one for power, one for the floats. 2" pipe would exit using a sweep from under the handhole, and enter the pit farther down. If you wanted, you could even try to seal this pipe with ductseal; I wouldn't bother.
How you get from the house to the handholes is up to you. I would -again- prefer pipe. Now, this pipe I would seal at the handhole - that swelling insulation issue again.
