Lightning and RF groundplanes are a big topic to cover here, but per ABYC TE-4 Lightning Protection, the lightning ground (an underwater plate or strip) is connected to the boat's main DC ground bus. Note that the mast downlead is led directly to the underwater ground plate, but seacocks and thruhulls (if included in the lightning protection) are connected to the lightning ground plate, not directly to the mast downlead. What you don't want are multiple ground systems at slightly different potentials, that introduces stray current.
Unfortunately shore power grounding galvanic corrosion issues are common, but can be easily dealt with by installing a galvanic isolator or better still, an isolation transformer. Not by cutting the green wire, please!
-Tom
buss--- In electricboats@yahoogroups.com, "John Green" <v_2jgree@...> wrote:
>
> Hi, Although not as boat (or electrical!) savvy as most here, I am refitting a gutted boat, and did get some insight from another forum a while back, re a caution they had about what I was assuming at the time.
>
> I have what I thought was a negative (side of battery) grounding system throughout the boat.
> It consists mainly of single strand heavy copper wires. They connect to a plate type item that has a through-hull connection, and to all rigging fittings. Down the centre of the boat it has copper straps.
>
> Apparently this is all part of a ground plane system for vhf radio, as well as static protection.
> The reason I am posting this is that apparently systems such as this should never be connected into the electricals as an overall boat negative ground system.
>
> Also during that other forum discussion (liveaboard.com) it seemed to be that the highest rates of problems were from shore supplied current, and bad grounding in marinas generally. The end result for me was to set my mind on having no shore power wiring, and to avoid marinas.
>
> my 2 cents,
> John
>
>
>
> 1e. Re: Rewiring DC electric system and Grounding
> Posted by: "John Raynes" johncraynes@... eboatdrives
> Date: Tue Mar 1, 2011 2:57 am ((PST))
>
> Brian,
>
> Thank you for bringing the "Grounding" question to this forum. I hope there
> is an expert among us who can really nail down how to create a ground for
> electric propulsion. I recommend a ground bus bar wired to the underwater
> metal, ie rudder and steering system and attached a ground wire from the
> negative side of the battery for my ground. Please others on this forum
> comment on this very important issue. Has ABYC finished the official rules
> inregard to grounding for electric systems??
>
> John Raynes
>
> --
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