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Old 13-08-2012, 07:50   #1
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Is My Shore Power Earthed Correctly ?

hello I have jut installed shore power in the yacht, and after plugging it in, I am getting electric shocks from my laptop! this seems odd, because after passing through its transformer the current into the laptop should / can only be 70W.

the shore power is earthed on shore, with a 10A RCD there. on board, the power passes through a 30A RCD,

the earth wire is earthed to a CGP, on the hull below the waterline .

the laptop chassis becomes live, when plugged in to the power socket on the yacht.

how? why? is the 'double earth' creating a circuit? any other ideas?!

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Old 13-08-2012, 16:09   #2
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Re: Is My Shore Power Earthed Correctly ?

Normally the laptop has a small transformer that converts the shore power to dc voltage, not sure how this makes the chassis hot. You've got some wires connected wrong and it's hard to diagnose over the internet. Maybe get a marine electrician to check it for you?
Brian Stetler
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Old 13-08-2012, 16:16   #3
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Re: Is My Shore Power Earthed Correctly ?

Quote:
Originally Posted by amarinesurveyor View Post
Maybe get a marine electrician to check it for you
If you're getting shocks, or you know for certain that the laptop is live with respect to boat ground, DEFINITELY have it checked out by an electrician.
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Old 13-08-2012, 16:24   #4
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Re: Is My Shore Power Earthed Correctly ?

what kind of grid to shore to boat power do you have?
volts, configurations, etc...
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Old 13-08-2012, 16:35   #5
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Re: Is My Shore Power Earthed Correctly ?

If you are getting a shock that you can feel, it is probably not the low dc voltage, but some stray AC higher voltage, which clearly indicates a wiring fault in the install. Unless you are very familiar with circuts, turn everything off, disconnect the shore power cord and contact a marine electrician before you do anything else. This is not something you can diagnose over the internet.
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Old 14-08-2012, 06:15   #6
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Re: Is My Shore Power Earthed Correctly ?

Quote:
Originally Posted by sdowney717 View Post
what kind of grid to shore to boat power do you have?
volts, configurations, etc...
reply to sdowney: 240ac 10A shore power with RCD, power taken to boat with 3 core. only live and neutral cables go through the boat RCD, the earth cable i have taken to CGP. onboard 3 core serves sockets in a loop round the boat cabin, earth taken to CGP. i guess the earthing must be at fault, but only two appliances (laptop and an electric pan) seemed affected. odd! unplugging now....
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