Re: [electricboats] How are you grounding your AC (shore power) and your 12 VDC subsystems?

-tv,

"How are you grounding your AC (shore power) and your 12 VDC subsystems?" is at least two questions amigo. This is what I'm saying. You can simplify the topic, but  only so much.  Connecting those two together can easily make a problem.

Really, these threads usually bring up a lot of good questions tho...and there's good reasons for that.  So for clarity, let's please just refer to the same E-11 drawings for examples.  Yes?  Here:

http://www.blackfinforums.com/sites/default/files/10/attachments/abyc-e-11.pdf

To be crystal clear: I let my AC green from shore power terminate only to the shield of the isolation transformer(s) exactly as shown in both diagram 6 and/or 7 on pages 37 & 39.   In audio we call this 'ground lifting.'  That ground stops there.  I mean, mine's actually got a power strip with up to three different transformers, all ground lifted just like that.  Four if I plug in the phone charger.  :-)  But that's the connections.

However, that diagram doesn't also show the 12V grounding you _also_ asked about, nor the system anodes someone else did.

So, please see Figure 18 Page 54 for that stuff.  I don't have exactly that particular gak shown, but that's the green wires' connections.  They connect to the negative battery terminal(s). In one and only one location.

Also to me, Figure 18 looks like maybe what your ABYC guy was trying to explain re: green wires, but I don't know where any kind of 'floating' enters into it.

Everything is depicted grounded _and_ ground referenced in _all_ those diagrams. Read the surrounding text. Everything is ground referenced in all the other E-11 diagrams too as far as I see. If ABYC is telling you floating your system is cool now then, you know, do whatever you want I guess.  People are doing it, if that's what you want to know.  Lightning prolly won't strike...right?  Hey, MinnKota does it!  :-)

You're asking: "Just tell me how."  Once you learn why it will become obvious what you want to do.

Ciao!

On Friday, August 5, 2022, 10:30:03 AM CDT, THOMAS VANDERMEULEN <tvinypsi@gmail.com> wrote:

Dave,
Lots of information in your post ... but did you include an answer to the question posed by this topic: to what are you connecting your AC safety ground wire?

ALSO, I question some of your statements with respect to connection of negative battery terminals to ground.  The DC grounding bus is not a connection the DC battery negative terminal.
This is what an ABYC Standards Developer in the ABYC Technical Department wrote to me just a few days ago on this exact topic:
"In isolated/ungrounded/floating DC system the main AC grounding bus (green wires) should be connected to the boat's DC grounding bus (green wires).

The DC grounding bus is where all green wires from metallic noncurrent carrying parts of direct current devices (e.g., metallic case) are connected. So you can have an ungrounded (aka isolated, floating) DC system, which means that the NEGATIVE side is not grounded (isolated from the ground), but have DC grounding bus where all green safety grounding wires are connected. Also, your cathodic bonding system (if installed) would be connected there."

I am currently in the process of making the final installation of my propulsion system, and bringing AC on board for the first time, as it was not installed by the mfg (Cape Dory). 
This ABYC Standards Developer also told me that since my DC propulsion system was 60 VDC or less, it is *not* coverd by ABYC E-30.  I made the mistake early on of assuming that *any* electric propulsion system was covered by this standard.

Anyway, I hope that readers can refrain from the theoretical discussions and didactic lectures -- of which as you point out, there are already plenty -- and get straight to the heart of the matter: to what have you attached your AC safety ground, and (if provided) the safethy grounding system of your 12 VDC subsystems?

Thanks.

[-tv]