Installing a sub-panel in a boathouse

[_greg_]

I live in NE Alabama and am building a boathouse. Part of the dock is built on 6" I-beams driven into the lake bed and has wood decking on top, the boathouse is being built on wooden pilings. I plan to install a 60 amp GFIC at the service box for the home, then run 3, #4 THWN wires and a #8 ground in pvc approx 160' to a sub panel located at the boathouse and use regular breakers there (I will have 6 or less breakers). I will keep the ground and neutral separate at the sub panel. After pouring over the NEC and reading an article on here by jwelectric I still have a few questions.
I understand the height location requirements of the sub-panel, but can a weather-proof sub panel be located on one of the supports for the roof? (there will not be a wall, just a roof).
Most of the info I can find about Equipotential Plane is for outdoor pools or spas. Do I just bond the I-beams together then drive a ground rod (1/2" water pipe no less that 5' long) next to an I-beam and run a #8 copper ground from the bonded I-beams and ground rod to the sub panel ground?
The NEC talks about having the Equipotential Plane extend 36" around the disconnect, which I believe in my case, would be the sub-panel?
Does that mean that there should be an Equipotential Plane on the wooden deck directly under the sub-panel?
Thanks for your expertise
greg

 

[WorthFlorida]

Grounding is like venting for plumbing, it seems so simple but it does get complicated. Please follow this link, there is a post on dock wiring.
https://terrylove.com/forums/index....ring-after-lake-shock-from-dock-wiring.76077/

Was the dock built from an engineered set of approved plans specific for this site? That is a local engineering firm designed it. If yes, then call them up and ask for the electrical engineer about bonding all steel beams to a ground rod with these beams in the water. If no plans, still call on an engineering firm. Maybe a call to the building department of your local jurisdiction. When it comes to an electrical inspection you do not want to do it rewire.