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#11652 - 07/18/02 01:00 PM boat dock wiring problem
ken m Offline
Member

Registered: 08/14/01
Posts: 61
Loc: south carolina
anyone have any ideas regarding that voltage tingling when touching the metal ladder as you climb out of the water? boat docks around here (western SC)are typically wired from a house circuit that is run underground to a pole and terminated either in a single unit breaker box with a gfi or a gfi receptacle. from that point a cord and plug runs along the dock gang-walk in conduit and onto the dock which may feed a light, an outlet for a battery charger or a boat lift.
this "voltage" is felt with nothing connected.
electricans have tried using ground rods, running #4 bare wire around the dock but to no avail. any ideas? thx., ken m

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#11653 - 07/18/02 02:53 PM Re: boat dock wiring problem
Bill Addiss Offline
Member

Registered: 10/07/00
Posts: 4196
Loc: NY, USA
Ken,

Are you touching a boat when this happens, or just coming out of the water? Does this happen when the circuit is turned off in the House?

Bill

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#11654 - 07/18/02 07:46 PM Re: boat dock wiring problem
electure Offline

Member

Registered: 12/24/00
Posts: 4226
Loc: Fullerton, CA USA
As well as your system you might check on the neighbors.
It could be you've got the best grounded boat dock in town!!

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#11655 - 07/19/02 03:02 AM Re: boat dock wiring problem
ken m Offline
Member

Registered: 08/14/01
Posts: 61
Loc: south carolina
i probably need to explain a bit further...yes bill, while in the water and you touch the metal ladder is when the sensation is felt. the docks are composed of wood planking over metal framework which sets on encapulated foam floats. then from each of the shore side corners are steel cables attached to a land based metal supports driven or cemented into the ground. some of the docks that have this problem have pumps mounted on them. (not submersible)ususlly 120v for washing boats or cleaning fish. also neighboring docks are at least 50' away.
one thing i did learn was the local power co. has lines running across the lake at various locations???? thanks for the comments, ken m

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#11656 - 07/19/02 03:05 AM Re: boat dock wiring problem
ken m Offline
Member

Registered: 08/14/01
Posts: 61
Loc: south carolina
this situation is with power on only.

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#11657 - 07/19/02 05:33 AM Re: boat dock wiring problem
Bill Addiss Offline
Member

Registered: 10/07/00
Posts: 4196
Loc: NY, USA
Ken,

If it is with power on only I was thinking there might be some 'leakage' in the wiring that comes from the House. (I figured if it was on the load side of the GFCI out there it would trip) Do you know anything about the wiring method coming from the house, and is it in good condition? Can you disconnect that wiring and try feeding the dock another way temporarily to see if the problem goes away?

Bill

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#11658 - 07/20/02 02:52 AM Re: boat dock wiring problem
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
Ken,

Is it possible for you to disconnect the underground feeder at both ends and do a megger test on it?

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#11659 - 07/20/02 07:17 AM Re: boat dock wiring problem
Bill Addiss Offline
Member

Registered: 10/07/00
Posts: 4196
Loc: NY, USA
I'm wondering if the 'leakage' could be detected with the circuit on and everything being off out at the Dock (or disconnected at that end) by using a milliAmmeter?

Bill

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#11660 - 07/20/02 01:09 PM Re: boat dock wiring problem
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
Bill,

The only problem I see with that is that by using AC you're going to read some current due to the capacitance of the cable (e.g. with 0.1uF you would expect to see about 4.5mA anyway) and that would mask any leakage due to bad insulation.

With a DC insulation test, the capacitance won't be a problem.

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