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post #11 of 18 Old 03-14-2017
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Re: Galvanic Isolator

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Originally Posted by eherlihy View Post
DO NOT confuse the AC Ground (aka neutral or white wire) with the GroundING (aka green wire).

The Ground should go to whatever AC load that you are connecting the AC to. The GroundING wire should connect to your vessel's bonding circuit. And, if your smart, you should have some form of galvanic isolation device for the vessel.
The white wire is Neutral, not to be confused with the ground. Neutral has never been called ground.
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post #12 of 18 Old 03-14-2017
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Re: Galvanic Isolator

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The white wire is Neutral, not to be confused with the ground. Neutral has never been called ground.
Not to ABYC. According to ABYC AC neutral IS called the "Grounded Conductor"

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11.4 DEFINITIONS

For the purposes of this standard, the following definitions apply.

11.4.1 AC grounded conductor - a current carrying conductor that is intentionally maintained at ground potential.

NOTE: This may be referred to as the neutral (white) conductor in AC electrical systems.


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Last edited by eherlihy; 03-14-2017 at 09:32 PM.
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post #13 of 18 Old 03-14-2017
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Re: Galvanic Isolator

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Originally Posted by misfits View Post
I can't wrap my head around this for the life of me.
Why would you connect an AC ground that under the right circumstances could back feed line voltage to a DC buss. What am I missing here?

Bob
Can you explain what circumstances that might happen?
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post #14 of 18 Old 03-14-2017
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Re: Galvanic Isolator

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Originally Posted by eherlihy View Post
Not to ABYC.
Here is your post:

Quote:
Originally Posted by eherlihy View Post
DO NOT confuse the AC Ground (aka neutral or white wire) with the GroundING (aka green wire).

The Ground should go to whatever AC load that you are connecting the AC to. The GroundING wire should connect to your vessel's bonding circuit. And, if your smart, you should have some form of galvanic isolation device for the vessel.
Difference: You called it AC Ground, ABYC calls it the AC Grounded Conductor

Your omission of "ed" changed the description of the conductor significantly.
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post #15 of 18 Old 03-15-2017
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Re: Galvanic Isolator

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Originally Posted by DotDun View Post
Can you explain what circumstances that might happen?
One thing I know for certain, electricity doesn't care what color the wire is....

On my boat the "shore" inlet is within 10' of the panel so the additional main breaker is not required.
If there ever was a short to ground (green wire) within this 10' & I landed the ground to the DC negative buss as some illustrations show, would that not put line voltage to the DC - buss?
Keep in mind my DC system is free floating, not grounded to anything but the negative terminal on the battery.

Maybe I'm overthinking this but I do not want to create a condition that could hurt anyone. Sounds like I need to have this discussion with a knowledgeable marine electrician.

Thanks,
Bob

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post #16 of 18 Old 03-15-2017
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Re: Galvanic Isolator

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Originally Posted by misfits View Post
Seeing how I'm in the process of re-wiring the whole boat I've been wondering where to terminate the AC ground. The old AC ground landed at the ICE which was connected to the thru hull bonding system & lightening bonded system, both of which terminate at a single keel bolt. I no longer have an ICE, but an electric drive.

My DC system is free floating, not grounded to anything but the - terminal on the battery.
Question on the table, where do I land the AC ground?
Is your drive shaft electrically connected to the motor from DC negative?

An AC short is most likely to come from a dual voltage device - charger or inverter. Without the alternative path to earth the AC/DC connection provides in such a case the DC system would likely become AC hot.

Brian
Living aboard in Victoria Harbour
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post #17 of 18 Old 03-15-2017
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Re: Galvanic Isolator

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Originally Posted by misfits View Post
One thing I know for certain, electricity doesn't care what color the wire is....

On my boat the "shore" inlet is within 10' of the panel so the additional main breaker is not required.
If there ever was a short to ground (green wire) within this 10' & I landed the ground to the DC negative buss as some illustrations show, would that not put line voltage to the DC - buss?
Keep in mind my DC system is free floating, not grounded to anything but the negative terminal on the battery.

Maybe I'm overthinking this but I do not want to create a condition that could hurt anyone. Sounds like I need to have this discussion with a knowledgeable marine electrician.

Thanks,
Bob
Power from a source is looking for a return path back to the source.

A short from hot to ground in the 10' inside your boat would trip the breaker in the shorepower pedestal.
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post #18 of 18 Old 03-16-2017
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Re: Galvanic Isolator

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Originally Posted by mitiempo View Post
Is your drive shaft electrically connected to the motor from DC negative?

An AC short is most likely to come from a dual voltage device - charger or inverter. Without the alternative path to earth the AC/DC connection provides in such a case the DC system would likely become AC hot.
The prop shaft is isolated from the motor. From what I've read this is typical for EP installations so the seawater doesn't become an electrolyte & suck the life out of your batteries or do other not so good things with underwater metals on your boat. That's why the DC buss is free floating. The zinc on the prop shaft only protects the wheel because of dissimilar metal issues.

I have no intent of renting a slip so marina "shore" power is off the table. If solar can't provide enough juice to keep the battery bank full I'll power the boat/charger(s) with a small Honda generator if needed.

That's all I know.

Bob

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