Why is the water level an issue if there are no splices below the dock? You could run that conduit under water if you wanted to. I said you could use "T" conduit bodies but it might be better to use 2 hole boxes and have the conduits daisy chain with no openings under the dock at all, (one in, one out) although they will accumulate water no matter where they are if they are below the boxes. I have never pulled a wire out of an underground conduit that wasn't wet it it had been there a while.
That is the standard install around here. The conduits run under the dock and come up to each box. These docks may be submerged in salt water occasionally. They were on Monday anyway. (T/S Colin)
