Shore power shorting problem

[longterm]

i have a 1990 C-30 Tall that I bought in February; at the time his shore power connection powered the boat just fine, and he's told me that he never had issues with it.

I'm on a mooring so didn't try shore power at my marina until this week...

When I plug the boat in, all is well; when I throw the main breaker in the boat, all is fine; however, throwing either outlets, water heater or the Mermaid (A/C) switch cause the dock's breaker to trip.

Nothing on the back of the panel jumps out at us; 3 questions:

Have any of you had this problem?

If I can't find someone to fix it in Nashville, are there techs who will travel to fix something like this? I'm desperate to get my air and heat working.

is there a block somewhere that we can't see where these AC connections are junctioned, other than the block right behind the panel?

We did this:

Shore to cable - fine
Shore to cable plugged into cockpit - fine
Same with main breaker on - fine
Same with any of the 3 sub-breakers on - throws the circuit breaker at the dock

Thanks for any help,

Bob

 

[jrowan]

You did not mention whether u have 30 Amp or 50 Amp service. Sounds like your A/C is drawing more then the 30 Amp output of the dock power rating. But if U were drawing more then the 30 or 50 Amp rating of your house service then your boat's main breaker should have tripped. Try plugging into a different shore power supply terminal & see if the problem repeats. Also make sure that you shore power cable connection is screwed in tight at both ends, or arching or shorting can occur. Also, check the Amp requirement of your A/C system - should be labelled on outside of unit. Your combined draw with the A/C, fridge, etc. may be exceeding the output max. But if it repeatedly tripps do not keep resetting the breakers. There may be a wiring fault causing the breaker to trip. Contact your marina manager for advice or electrician testing.

 

[Barnacle Bill]

Also make sure you have a proper shore power cable. You probably do, but some people use extension cords with adaptors and they cannot carry the juice required for the boat.

 

[longterm]

You did not mention whether u have 30 Amp or 50 Amp service. Sounds like your A/C is drawing more then the 30 Amp output of the dock power rating. But if U were drawing more then the 30 or 50 Amp rating of your house service then your boat's main breaker should have tripped. Try plugging into a different shore power supply terminal & see if the problem repeats. Also make sure that you shore power cable connection is screwed in tight at both ends, or arching or shorting can occur. Also, check the Amp requirement of your A/C system - should be labelled on outside of unit. Your combined draw with the A/C, fridge, etc. may be exceeding the output max. But if it repeatedly tripps do not keep resetting the breakers. There may be a wiring fault causing the breaker to trip. Contact your marina manager for advice or electrician testing.

Thanks for the input; I did try a different pedestal, with the same results. Other boats aren't tripping it...

A friend there who has a Beneteau 42 told me he had the same problem, which he solved with some device that he said runs a little more than $300. Fortunately there's an electrical engineer at our marina who has a C30, so he's my next person to call.

I'm using a good shore cable; as I mentioned, plugging cable into dock doesn't blow anything, nor does plugging it into the boat or turning on my main breaker. The circuit pops when I turn on any of the 3 circuits--outlets, water heater, or A/C. I have a hard time believing I've got shorts in three separate circuits.

The friend I spoke to mentioned that I probably have a capacitor that's causing the trip, but I'll get more details in a few days.

 

[rbmcintire]

LT, it's just those Lake Nymphs tweakin' ya to get off the dock an' go sailin'!

Seriously, I agree it's not likely you have three bad circuits at the same time, especially if it happens when you separately turn on any one of them. It's something common to all most likely, and to state the obvious you have a hot wire going to neutral/ground or a ground wire touching a hot. Could be they've been pinched and have worn together somewhere. It's always time or money. Following all safety precautions and ABYC/ NEC codes, the troubleshooter will disconnect all of those circuits at the panel and then add one back at a time to determine which is the culprit. Then it goes to tracing it down through the boat as necessary. Let me reiterate the, be careful, be thoughtful, be safe, part.

Good Luck

Rob