380 DA Tripping Shore Breaker

(Also posted under electronics, but trying to get some responses)

Came home from a long trip where we stayed at no fewer than 8 different marinas. No unusual power issues.

Get to home marina after a 4-hour lake run, plug in shore power, and BAM..... breakers blow immediately on the pole when ANY load is placed on it. Normally I run a single 30 amp to a dual 30 Y-cord, so I pulled out the Y and....

Tried:

Running with two 30 amp cords to multiple poles.

Tried each 30 amp input by itself, and switched cords and stanchions.

Moved to another section of the marina and tried their stanchions.

No go.

Everything DOES run on the generator without tripping anything.

Any ideas where to even start?

The problem is in the boat or the power cords.

Did you try someone else's cables?

Check the males where you plug the cables in (in the lazarette) - any charring?

Check the cable ends for charring.

No visible charring on any exposed prongs of any cables. Tried different cables.

Turn off all the breakers in the boat.

Plug boat into shore power.

Then turn on boat breakers one at a time.

That would help identify the problem circuit.

If shore power still trips when plugged in with nothing on in the boat then it's something before your main boat breaker like the outlet in the lazarette is defective.

I did that. It doesn't trip just by the mains being on, it immediately trips when any of the individual breakers are turned on and drawing a load (microwave, fridge, A/C, charger) doesn't matter which one. Starting fresh it reads full 125+volts per side, zero amps. Then choose a breaker to open and 'snap'.

And again, it happens with either line plugged in separately or together.

Ugh.....

Island Time Buffalo said:

I did that. It doesn't trip just by the mains being on, it immediately trips when any of the individual breakers are turned on and drawing a load (microwave, fridge, A/C, charger) doesn't matter which one. Starting fresh it reads full 125+volts per side, zero amps. Then choose a breaker to open and 'snap'.

And again, it happens with either line plugged in separately or together.

Ugh.....

Click to expand...

Time to call an electrician ..... some electrical component must have melted causing a dead short.

I've exhausted my knowledge. Electrician is on the way.

Island Time Buffalo said:

I've exhausted my knowledge. Electrician is on the way.

Click to expand...

Once figured out please let us know..... we might all have a part that is slowly failing.

Yeah, tracking this also.

Partial update. Still waiting on my electrician, hopefully this weekend, but I have confirmed that it only trips on GCFI circuits. The problem is still within my boat and it is something that recently changed, but it explains why I was able to hit 8 marinas without issue in the past 2 weeks. My understanding is that the majority of marinas are still not GCFI - even relatively newish ones.

Neutral-to-ground leak somewhere.....just gotta find the mofo.

SOLVED! It took some sleuthing, and some help from a qualified electrician. It is my salon air conditioner. Not sure what component, probably the compressor, leaking just enough neutral to pop the GCFI - regardless of whether it was on or off at the breaker.

I completely disconnected the hots and the neutrals and taped them off and put everything back together. I can get by just fine on the forward air conditioner. A problem for the off-season.

Glad you figured it out. Its great when people take the time to let everyone know what the issue was. So many ask questions, get many responses and never respond.

My electrician says that electric motors are notorious for being the cause of a neutral leak that pops GCFI..."spinny things"... so the motor in the microwave turntable, A/C fans and compressors, etc.... all good places to start.

Good info, and luckily it's easily accessible.

Nice work finding it!
What's the fix for something like that?

rondds said:

What's the fix for something like that?

Click to expand...

Good question. Haven't even started to look yet. My guess is a new compressor, maybe a whole new unit. But since that A/C basically only feeds the mid cabin, I usually don't have it on anyways, so I'll just be putting that one off for a bit. I'll post what I find when I get there.

Since I spent much energy and time on this, I thought I would share the techniques we used to locate this bad boy. This seems to be a common problem and the "The Google" has slews and slews of circular information. I'm sure this doesn't cover every scenario, but I suspect it covers a lot.

This Case's Symptoms: It worked fine on a non-GCFI outlet. But plugging into shore power with a GCFI would trip once a load was placed on it. But not across the board. I could bring up seemingly random circuits (water heater for instance), but most would pop it immediately. You could isolate either line and it would still pop.

You start by eliminating the easy stuff. Try different cords, pedestals, etc. Then try isolating each breaker. Turn off all, then bring them on one-at-a-time.

Then we're at my scenario - random popping on multiple circuits. Indicates a neutral leak. The GCFI detects small variations between the hot and neutral circuits, and isolating breakers only checks for the hots.

Go to the neutral bus bar, probably right behind your breaker panel, it's the bar with all the white wires going to it.

You will find a white lead for each of your breakers, plus a main for each line in.

KILL THE POWER AT THE PEDESTAL FIRST. Then turn off all the breakers in the panel.

Then start with one white lead and disconnect it. Either tape it off or at the least ensure it isn't touching ANYTHING.

Then power up at the pole. Turn on one breaker at a time, then off. There's a catch: With the neutral lead disconnected, that specific breaker will still pop the GCFI when you open it. But it shouldn't pop any of the others - so you will have to reset it a couple times for each white lead you disconnect. If you are still popping multiple breakers, then reconnect the wire and move to the next.

When you have a disconnected white lead that allows all the other circuits to operate, and only pops the one, you have isolated the problem circuit. Most of them are single serve (water heater, microwave, salon air conditioner) so it's usually obvious what component has the issue.

While it still doesn't explain what's wrong with the component, at least you know what to look at.

( all this of course assumes there is only one bad circuit. If you've been hit by lightning or something, all bets are off).

Very interesting. Thanks for the detail. Could you pick the brain of a marine air condx guy or Google to see if the AC unit can be saved?

I had a breaker in the power tower here at my slip corrode away yesterday. My slip neighbor and I opened it up for the diagnosis. As a result for a few hours I was able to run just the salon air condx, and it got warm in the boat. It wasn't cycling and struggled to maintain 75*.