AC DC grounding

The best solutions are always simple, but most often it was long and not straight way to get to them.

I agree with you, but in example in my area, I was told by one specific equipment seller, that I was the only private person ever asking about the isolation transformer for boat, and even many boats for proffessional use do not have them. My wild guess is that it is a rare animal on boats, especially on recreational boats. People do invest in inverter because of comfort/convenience (refrigireator, air condition unit, electric tools, etc.), but how many are ready to invest in isolation transformer because of safety/bonding/etc, how many boat users even have any clue about it?

Regarding standards, I think most of them have legacies which are difficult to let go, even when rewritten for relatively new applications. Could be that writers do not want to risk missing some legal issue from the past that could be overseen.

Obviously we are both coming from similar proffesion. Though, marine sphere is just my personal interest/hoby which I enjoy.

Just as a side note, seacocks on my boat are made of gunmetal (closest available to bronze that I found on the market) and left alone (unprotected).

And something I have already noted in one of the previous messages, mind the responsibility of unofficial advising about electrical installations!

 

Most people with Class A boats have isolation transformers, but uncommon in most recreational smaller boats.

 

You don't often see isolation transformers on recreational boats in the USA until you get up in size to where they pretty much run everything with AC, or higher DC voltage (48 V and up) systems. Most smaller recreational boats have a galvanic isolator. They are relatively cheap, easy for a boat owner to install, and take care of the DC leakage problem. But AC is being installed on smaller and smaller boats now, because owners want Air Conditioning and real refrigerators, Big screen TV's etc. To see this all you have to do is go to a boat show that has houseboats, or yachts much longer than 30 feet. I've even seen washers and dryers on houseboats. It's amazing the stuff manufacturers put into their boats now. Personally I'll stick with 12V DC.

 

An AC not bonded system is basing safety on the belief that the AC system is properly grounded. The neutral can have a potential to kill a person if the supply is not properly grounded. Even if it is bonded to ground at the entry in the marina, the resistance of the ground/water between the ground rod and the boat is enough to create a significant potential.

 

Not when RCD/GFCI protection is enabled.
How many times must it be repeated?
Those devices trip with an imbalance between hot and neutral.
The path(s) to "ground" do not matter whether it be you or a wire.
The only thing that matters is a difference in electron flow between hot and neutral, (black and white).

 

How about the AC ground from the outlet at the dock?

 

I believe that fairly recent legislation and or codes now require dockside outlets to have GFCI protection.
It's been far too long in coming.
This video may explain just what you're addressing.
As an aside, Kevin Ritz has been a friend of mine for well over 20 years, and he is a court certified witness for issues pertaining to ESD and electrical corrosion problems in the marine environment.
He is the one who "wrote the book" on these subjects, and has taught classes at the Coast Guard Academy, and "Teaches the teachers" for the ABYC electrical certification classes.

 

Yes the regulation exists, but is not enforced in most places. It will take a while.