ship to shore power issue

boater184

Cadet
Joined
Oct 16, 2013
Messages
15
My 1989 Bayliner Cierra shore power keeps blowing the gfi outlet on the dock, different gfi's, so I'm sure its not the dock power, especially since other boats are hooked up with no problem. So when I first plug in, with all the breakers turned off and the master power switched turned off, its fine, however the green power indicator light glows and flickers very faintly. As soon as I turn on the main breaker, even with the individual breakers still off, it breaks the Gfi circuit. The cable is good, and I have replaced the cable receptacle on the boat. This spring when I first launched it all worked fine, then after a few weeks it started blowing the Gfi.
What gives, is the very faint indicator light a tell-tale something that could be wrong ?
 

Grub54891

Vice Admiral
Joined
Jun 17, 2012
Messages
5,908
Well, yes you have a problem. Be very very careful to not get shocked. It could be actually draining power directly in to the water around the boat. Sometimes breakers just wear out and will not hold any load either. A flickering power light sometimes means reverse polarity at the cord/boat. be sure it's wired correctly. Sounds like the issue is between the dock and boat at this point. The best fix is to have a marine certified Abyc trained electrician diagnose the issue. Keep us informed of what you find. A land based electrician may not know how a boat should be wired.
 

muc

"Retired" Association of Marine Technicians...
Joined
Jul 7, 2004
Messages
2,064
A flickering light is almost always an indicator of a problem. But those lights are commonly neon and flickering isn't uncommon when they start to die.
Do you have a reverse polarity light? Does it have a switch to test it?
How a boat is wired for shore power has changed dramatically over the years. Is your setup factory or installed at a later date.
Most shore power on smaller boats is a 30 amp setup with twist lock plugs on the shore power cord. The outlet on the dock isn't usually protected by GFCI it might be good for you to describe exactly your system or post up some photos.
The most common cause of the problem your having is a connection between the groundED circuit and the groundING circuit.
Pay attention to what Grub says, people and pets die due wiring problems on boats every year.
 

boater184

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Joined
Oct 16, 2013
Messages
15
Thanks, to both of you. I'm trying to find someone on the dock who might know someone who might know something about these type of systems. The trouble is, in southern Iowa, finding someone who knows about this is kind of tough. I'm pretty sure this is all factory setup, It doesn't look to be added on. I do have a reverse polarity indicator light on the panel, it has never came on. No reset switch though. I will heed your advise on being careful with this deal !!
 

muc

"Retired" Association of Marine Technicians...
Joined
Jul 7, 2004
Messages
2,064
see if a slip neighbor will let you try their cord.
 

mjf55

Chief Petty Officer
Joined
Jun 17, 2014
Messages
462
As Muc suggested, try another cable. After that, you need to do some basic trouble shooting. BE CAREFUL, YOU ARE DEALING WITH LETHAL VOLTAGES.
What kind of connector do you have? Look at the attached picture. Using a DVM, on > 200 v ac setting, verify that you have 120 volts between hot and ground (black and green), hot and neutral ( black to white )and 0 volts between neutral and ground ( white and green )
Shore-Power-1.jpg

Try and post back and we can continue.
 

boater184

Cadet
Joined
Oct 16, 2013
Messages
15
I have the 30 amp locking connector, I do have an electrician friend up in Des Moines I'm hoping I can get to test my cable, thanks I'll report back what he finds.
 

Grandad

Lieutenant Commander
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Jun 7, 2011
Messages
1,504
I'd suggest that you have your electrician check for voltage (milli-voltage) between the ground pin hole of your cord and the ground prong on your boat while it is plugged into shore and unplugged from the boat. If there are multiple shore panel services and subsequent ground points for those services, you can have "stray" voltage issues at the marina which will play hell with the sensitivity of a GFCI. Your boat and everyone else's provide additional ground points through engines and other equipment. - Grandad
 

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,598
I was having a similar problem this Spring. The 30A dock receptacle is wired to or through the 15A GFI receptacle, and I was triggering the GFI. One of my breakers is for the onboard charger, and the old charger was apparently the issue -- although the charger was not flipping the breaker, just the GFI at the shore receptacle.

I turned off all breakers, plugged in the shore cord and switched on the main breaker (no issues). Of the three dedicated circuits/breakers, only the breaker for the charger triggered the GFI. I have a new charger that plugs into one of the receptacles controlled by one of the other breakers, and that is what I've used this summer.

Anyway, you might follow a similar procedure to isolate the problem circuit. I can't say for sure that the old charger is actually the problem, rather than the breaker switch, and will leave that and any rewiring for the off season.
 
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