Transformer Grounding

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billjensen

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I am currently wiring a dock that is approx 500' long. This dock is being fed with a 480/240 transformer located approx 300' out from shore. Since this will then be considered a seperately derivied system I know I need to bond the case to the neutral on the secondary side, but do I need to run a ground wire back to shore and install a ground rod? Any help will be greatly aprreciated.
 
Re: Transformer Grounding

Maybe you could get a scuba diver to pound a ground rod into the lake bed under the pier.

:)

Seriously, why not make a concrete encased electrode up and just throw it over the side into the bottom of the lake. Run the GEC up a leg of the pier and connect to the CEE. Ought to be a near ideal GE.
 
Re: Transformer Grounding

I think this may fall under Art 555:

"555.1 Scope. This article covers the installation of wiring and equipment in the areas comprising fixed or floating piers, wharfs, docks, and other areas in marinas, boatyards,
boat basins, boathouses, yacht clubs, boat condominiums, docking facilities associated with residential condominiums, any multiple docking facility, or similar occupancies, and facilities that are used, or intended for use, for the
purpose of repair, berthing, launching, storage, or fueling of small craft and the moorage of floating buildings."

"555.5 Transformers. Transformers and enclosures shall be specifically approved for the intended location. The bottom of enclosures for transformers shall not be located below the electrical datum plane."

I would think you may be able to install the grounding electrode in the area below the dock, but I am not really sure.

[ June 17, 2005, 12:23 AM: Message edited by: pierre ]
 
Re: Transformer Grounding

bill,

I would call the AHJ and confirm with them. I think technically you need to run a wire back to the shore and drive a ground rod. I don't see how this will make any difference if you are pulling a ground with your 480 feeder and grounding the transformer and secondary neutral.

Although it is probably not code compliant, dropping a ground into the water really makes a lot of sense in my mind. The thing that I don't know enough about is creating a corrosion cell for the boats. I've read articles about how having a common grounding system that all the boats are plugged into and conductive water that props are in is a perfect situation for cathode/anode system. Someone with anodes on there prop may see them corrode and disappear in 30-60 days, then whoever has the most vulnerable prop will go next (and so on and so on).
 
Re: Transformer Grounding

Originally posted by petersonra:
Originally posted by ryan_618:
682.10 and 682.12 would not permit this, as it is obviosly below the elctrical datum plane.
Click to expand...
what code is this from. It's not in the 2002 NEC.
Click to expand...
2005 Naturely and Artificially made bodies of Water.(new)
 
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