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#79874 - 02/03/02 09:28 AM Marina grounding and stray neutral current.
tdhorne Offline
Member
Registered: 03/22/01
Posts: 345
Loc: Maryland, USA
The issue of the current flowing over EGCs on boat shore lines has come up elsewhere. I realize that the wiring of water craft is totally beyond the scope of the electric code but we had two people drown here recently when the leaking ground current caused people swimming near a dock to loose control of their bodies. Can anyone here tell me what standards do apply to the power systems on water craft. How would a responsible marina operator address this hazard. If they are functioning in a competitive environment how can local AHJs assure that the transfer equipment used on the boats transfers the grounded conductor (neutral) along with the Equipment Grounding Conductor?
--
Tom
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Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison
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#79875 - 02/03/02 10:03 AM Re: Marina grounding and stray neutral current.
Joe Tedesco Offline
Member
Registered: 10/07/00
Posts: 2749
Loc: Boston, Massachusetts USA
See NFPA 303, Fire Protection Standard for Marinas and Boatyards
2000 Edition

See Chapter 3 for Electrical Wiring and Equipment, See Section 3.5 for Grounding Requirements.
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#79876 - 02/03/02 01:09 PM Re: Marina grounding and stray neutral current.
tdhorne Offline
Member
Registered: 03/22/01
Posts: 345
Loc: Maryland, USA
Joe Tedesco Wrote:
"See NFPA 303, Fire Protection Standard for Marinas and Boatyards
2000 Edition

See Chapter 3 for Electrical Wiring and Equipment, See Section 3.5 for Grounding Requirements."

Joe
Does the standard you named address the wiring on the water craft? The problem arises out of the wiring on the boats them selves. The use of single and double pole transfer switches in place of the two and three pole ones that are needed to transfer the grounded conductor is the problem. I only have a 95 edition of the standard here.
--
Tom
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Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison
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#79877 - 02/03/02 02:04 PM Re: Marina grounding and stray neutral current.
Joe Tedesco Offline
Member
Registered: 10/07/00
Posts: 2749
Loc: Boston, Massachusetts USA
Tom: I goofed trying to provide assistance! I should have identifed the following:

"NFPA 302, Fire Protection Standard for Pleasure and Commercial Motor Craft
1998 Edition"

See Chapter 7, It is quite lengthy and with many revisions, I am sure, since your last 1995 issue.

Look at that standard on the NFPA web site if you subscribe to the NFC's?
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#79878 - 02/03/02 02:48 PM Re: Marina grounding and stray neutral current.
tdhorne Offline
Member
Registered: 03/22/01
Posts: 345
Loc: Maryland, USA
Joe

I don't have a subscription to the NFCs. Does "NFPA 302, Fire Protection Standard for Pleasure and Commercial Motor Craft 1998 Edition" address the on board wiring of the boats themselves? The absence of a pole in the transfer switch to transfer the neutral from the on board source of AC to the shore line is the source of the problem. The on board Grounded Conductor and the on board Equipment Grounding Conductor are bonded together at the source. If the Grounded Conductor does not transfer then the neutral currents from the boats will flow over the EGCs and through the water causing stray currents and voltage gradients everywhere.
--
Tom



[This message has been edited by tdhorne (edited 02-03-2002).]
_________________________
Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison
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#79879 - 02/03/02 07:30 PM Re: Marina grounding and stray neutral current.
Joe Tedesco Offline
Member
Registered: 10/07/00
Posts: 2749
Loc: Boston, Massachusetts USA
Tom:

See Section 7-2. Yes, I believe it does. You can call NFPA and ask for further assistance.
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Joe Tedesco, NEC Consultant
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