grounding AC via distribution panel bus bar?

[Buddy_Y]

My ongoing refit of an C&C 30 involves replacing the 1973 AC system completely, and my trusty Don Casey manuals tell me I should ground it to the engine / DC ground bus. I know this is isn't everyone's cup of tea, but I'm going to err on the side of caution.

My question: rather than splice in a wire from my AC run to the bus / engine, can I just run a ground wire from an unused terminal of the ground bus of my Blue Seas AC distribution panel (which is this one) to the ground bus / engine?

[wingssail]

Originally Posted by Buddy_Y

My ongoing refit of an C&C 30 involves replacing the 1973 AC system completely, and my trusty Don Casey manuals tell me I should ground it to the engine / DC ground bus. I know this is isn't everyone's cup of tea, but I'm going to err on the side of caution.

My question: rather than splice in a wire from my AC run to the bus / engine, can I just run a ground wire from an unused terminal of the ground bus of my Blue Seas AC distribution panel (which is this one) to the ground bus / engine?

Let's hear what the experts have to say, but my experience with this is, NO (don't connect the AC ground to any part of the DC ground)

Some, (many?) marine inverters connect the neutral AC wire to the Ground wire. If you connect the AC panel's ground to the boat's DC ground then you effectively have half of an AC potential on ALL of your boat's grounds. And this is in addition to having the AC grounded in more than one place.

But if you don't mind having a little tingle whenever you touch a grounded part of your boat, then it doesn't matter where the connection is made, go for it.

[Buddy_Y]

Originally Posted by wingssail

Let's hear what the experts have to say, but my experience with this is, NO (don't connect the AC ground to any part of the DC ground)

That's an ongoing debate over on this other thread. Cheers.

[goboatingnow]

Fit an RCD to the feed in and don’t connect AC earth to DC ground

[BAD ORCA]

Originally Posted by goboatingnow

Fit an RCD to the feed in and don’t connect AC earth to DC ground

May i ask what an RCD is?

[boatpoker]

Originally Posted by wingssail

Let's hear what the experts have to say, but my experience with this is, NO (don't connect the AC ground to any part of the DC ground)

Some, (many?) marine inverters connect the neutral AC wire to the Ground wire. If you connect the AC panel's ground to the boat's DC ground then you effectively have half of an AC potential on ALL of your boat's grounds. And this is in addition to having the AC grounded in more than one place.

But if you don't mind having a little tingle whenever you touch a grounded part of your boat, then it doesn't matter where the connection is made, go for it.

1. ABYC requires AC ground be bonded to the DC negative.
2. Inverters are "power sources" and a proper "marine inverter witk switch to a bonded neutral only when in use.
3.ABYC requires AC neutral/ground bonds at power sources only. i.e. generators and inverters.

[boatpoker]

Originally Posted by BAD ORCA

May i ask what an RCD is?

Residual Current Device. very similar to an ELCI with a different rating

[seabreez]

Originally Posted by boatpoker

1. ABYC requires AC ground be bonded to the DC negative.
2. Inverters are "power sources" and a proper "marine inverter witk switch to a bonded neutral only when in use.
3.ABYC requires AC neutral/ground bonds at power sources only. i.e. generators and inverters.

I operate a steel boat with two generators and a shore connection when in port. Last week the electrical panel was opened and the ground from shore was missing. A marine surveyor looked at it and said a ground has to go on immediately. One was put on within the hour... he relied on ABYC...

[Frankly]

Originally Posted by Buddy_Y

My question: rather than splice in a wire from my AC run to the bus / engine, can I just run a ground wire from an unused terminal of the ground bus of my Blue Seas AC distribution panel (which is this one) to the ground bus / engine?

If I understand your question, the bus to bus is a proper way to implement this ABYC required connection.

If an inverter is in your future you need to consult the inverter info for proper sizing (ampacity) of this conductor. Dont't be suprised if it turns out to be on the order of #4 AWG.

What also needs to be addressed is inclusion of an galvanic isolator in the green shore power conductor to reduce corrosion issues that the ground to ground connection might introduce (can you say catch 22).

Finally if you are really trying to bring AC things up to date, a RCD main circuit breaker should be included. "The life you save may be your own".

There are those that say with the RCD main breaker you do not need this ground to ground connection. Maybe so, just ain't the current regulation.


Frankly

[Buddy_Y]

Thanks for the advice, everyone!

[goboatingnow]

Originally Posted by Frankly

..
There are those that say with the RCD main breaker you do not need this ground to ground connection. Maybe so, just ain't the current regulation.


Frankly

In the US , only and it’s not a “ regulation “ it’s a recommendation

[Frankly]

ABYC Standards are the basis of certification programs, marine surveys, and legal judgements. In product liability lawsuits, ABYC Standards are the authoritative reference for evaluating issues of design, construction, maintenance, and product performance.


Where I live and where I practiced until retirement. Also where most of the world's lawyers are hold up.


Frankly