Shore Power Pedestal Tripping

Hi all. My marina installed the new compliant shore power pedestal breakers. Less mA’s to trip the shore breaker. I have a 1982 Albin 40 so… queue the problem…. When I go to turn the main breaker on to my AC panel, it trips the shore power pedestal even though no other breakers are closed on my panel. Can someone tell me where to start troubleshoot? Maybe this will give me a good chance to rewire the boat….

Do you have an inverter? If you do then the inverter load neutrals have to be on a separate buss. And that might not be the only problem. Lots of discussion on TF about this.

First thing to check is whether there is continuity between the neutral and the ground on your HVAC circuit. There shouldn't be.

These are great suggestions for me to start looking. I plan on disconnecting all the sub breakers and start from scratch. I guess my main question is, why would the shore breaker be tripping immediately when I close the main panel breaker, if all the sub breakers are open?

You have something basic wrong with your boats wiring. Some of the things noted above can cause it. Do you have 2 30 amp inlets? If so some or all of the neutrals may be comingled together. The best advice I can give you is to get an ABYC certified electrician to check it out. If you are asking these questions then get an expert.

SeaBoy said:

These are great suggestions for me to start looking. I plan on disconnecting all the sub breakers and start from scratch. I guess my main question is, why would the shore breaker be tripping immediately when I close the main panel breaker, if all the sub breakers are open?

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You probably have a bonded neutral and ground on the boat. When running on shore power, the ground needs to run back shore in the shore cable and not be tied to neutral on the boat. This assumes no isolation transformer.

SeaBoy
This is a fairly common problem with older boats and new marinas.
Here are some links to read about it to understand the causes and why it is an important safety item. If you are not up on the details and how to diagnose & repair it may be best to hire a pro. This should be fairly straight forward for a pro so it isn't necessarily a huge project to fix, at least in many cases it is one or two pieces of equipment. the challenge is identifying which ones and how to correct the issue(s)

https://www-passagemaker-com.cdn.am...om/technical/troubleshooter-shorepower-danger

https://www.marinadockage.com/technical-bulletin-electrical-changes-marina-code/

Does anyone know a good ABYC electrician in the Rhode Island Area? It looks like I’m going to need a clamp on ammeter that’ll sense somewhere around .04mA to diagnose this which will run me around $500. Maybe it’s best I have someone help. I’ll take a look at my inverters to start and will likely go with an isolation transformer just to get power back onboard

The first thing to start with is the power cord by itself. I was in one marina and i tripped it the dock hand told me he has see plenty of old power cords that trip the breaker. Unplug it from the boat and see if you still trip it.
The second thing is the lights that indicate reverse polarity. Disconect them and see if it trips. There have been brand new boats that those were causing it to trip.

Okay I will check that too. Does anyone else have ideas of this to check and how to check them?

Assuming you have a volt-ohm meter...


Unplug your shore cord from the boat receptacle, and set the boat's breakers the way they tripped the shore breaker. Now measure the resistance between the ground and neutral at the boats power inlet. It should be infinite. If it's zero, or a low number, then your ground and neutral are connected onboard your boat. That would be at least one problem.


If it is a problem, fixing it is not necessarily as simple as finding and removing the connection. If you have a generator or an inverter, then when either of those is your power source you DO need the ground and neutral connected onboard. There are many ways to accomplish this, but all will be very specific to your boat, and likely where you need to call in reinforcements to help figure it out.

This Boat US article has a basic troubleshooting process that might be helpful.

Troubleshooting: Electrical Safety

Our last boat would trip the breaker as soon as I would plug it in. It had 2 30 amp shore power inlets. There were several problems with the wiring but the main reason for the dock breaker tripping was that all of the neutral wires were on one bus. Another problem was that there was only 1 main 30 amp breaker, the second inlet was wired directly into the power bus without any over current protection. I ended up replacing the main electrical panel so I had 2 30 amp main breakers. I added a second neutral bus and had to figure out which neutral went with shore power #1 and which went with shore power #2. Since they weren’t labeled and were all individual wires it took a couple of days to ring out all the wires and separate the bus 1 and bus 2 neutrals. That took care of the dock breaker tripping. A friends boat was tripping the dock breaker. It also had all the neutrals on one bus, had a plug that someone had reversed the neutral and ground wires, the neutrals for the voltmeters were off one shore power and his water heater had a short inside it from ground to neutral. We fixed those 4 issues and his boat was good.

Follow advice above, and IMO get a good marine sparkie on the case early.

I had a tripping problem a while back, which might be completely different to the OP but something to consider also if the obvious checks/fixes don't work. In my case shore power would trip at the pedestal about 50% of the time on first connection. Even when all panel breakers were off.

The solution was installing a varistor, as well as a capacitor, but varistor was the main fix. It was explained to me that because I have 2 Charles transformers (one as isolation function and one as step-up or step-down depending on whether US or EU shorepower is connected) as well as an inverter there was a large amount of iron on which electric fields needed to be established at connection. The mods noted above tamed the inrush voltage/current spike a bit, enough to fix the issue. Newer transformers likely have the necessary components built in. Mine are 10 years old. It may be similar in effect to "soft start" mods that some A/C systems need.

So I purchased two 30a isolation transformers (at $900 each) and this will solve my problem. I bought two for each 30a receptacles onboard. I need to tie my neutral buss to the ground bus. Then ground bus to generator ground. Then to a sea cock. I should be good to go

SeaBoy said:

So I purchased two 30a isolation transformers (at $900 each) and this will solve my problem. I bought two for each 30a receptacles onboard. I need to tie my neutral buss to the ground bus. Then ground bus to generator ground. Then to a sea cock. I should be good to go

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typically, the neutral/ground connection is made at the power source (transformer) itself, not at the buss at the panel. if you have an inverter, it should also have the capacity to make a neutral/ground connection as it would become the power source.
there has been a lot of discussion on this subject here on the forum should you choose to do a little reading on the matter.

The neutral and ground should only be connected at the source of power, the dock or the generator. The transfer switch should take care of connecting them for the generator.

Is the transfer switch internal to the generator? Or are you talking about my ship to shore disconnect switch when swapping over

There are several different types of transfer switches. One is a rotary switch. Some are on the panel itself. But the neutral to ground connection is only made on the boat when power is being supplied by the generator. This is potentially a very dangerous thing if done incorrectly. You shouldn’t try doing this work if you are not pretty knowledgeable in boat electrical work, not house electrical work because it is different. I would advise you to get a certified marine electrician to either do the work or to show you how to do it. Don’t rely on internet advice for something this potentially dangerous.

When an isolation transformer is used, it’s fine to have a single, centralized, common bonding point between neutral and ground. This works and is allowed because the secondary of the isolation transformer IS the source of power on the bot for shore power, so all the possible power sources are on board and can be bonded in once single location. It’s typically done at the main electric panel. The actual shore cord terminates at the isolation transformer, and its ground is connected to an internal shield in the transformer that is isolated from the secondary ground for the xformer. Note that is assumes you bought marine isolation transformers that actually have the separate shield. A generic transformer probably does not.

It was neutral and ground connected on ours

We had that on our 1997 Mainship. The electrician found neutral and ground connected right behind the panel. He took off two wires and the problem is supposedly solved. (Haven’t been to a sensitive power pedestal yet since then.)

He said he was sure it was like when built, because the wires looked just like all the other original ones.

Good luck with your search!

SeaBoy said:

Hi all. My marina installed the new compliant shore power pedestal breakers. Less mA’s to trip the shore breaker. I have a 1982 Albin 40 so… queue the problem…. When I go to turn the main breaker on to my AC panel, it trips the shore power pedestal even though no other breakers are closed on my panel. Can someone tell me where to start troubleshoot? Maybe this will give me a good chance to rewire the boat….

Click to expand...

You said an isolation transformer solved your problem.

I have a 1986 Tollycraft that had a complete rewire about 15 years ago.

Someone the other day said that my galvanic isolator should solve this from being a problem at the newly rewired marinas.

Anybody know if that sounds right?

@ORIF #22

I just threw the BS flag!

A GI blocks, well, galvanic current, and passes alternating current that has made its way into the safety ground (green wire) system through a fault.

ORIF said:

You said an isolation transformer solved your problem.

I have a 1986 Tollycraft that had a complete rewire about 15 years ago.

Someone the other day said that my galvanic isolator should solve this from being a problem at the newly rewired marinas.

Anybody know if that sounds right?

Click to expand...

Not even close…

Agree...
Big difference between an isolation Xfmr and galvanic isolator.
Isolation xfmr eliminates tripping GI NOT!

Just installed my isolation transformer and my power problems are solved

SeaBoy #26:
You had two problems:
1. A N>G bond on the boat other than at a power source.
2. A water path back to the transformer secondary feeding your pedestal.

The isolation transformer has only eliminated problem #2.

Yep, as I understand it, the current leak into the water is still there in that case.

SeaBoy said:

Hi all. My marina installed the new compliant shore power pedestal breakers. Less mA’s to trip the shore breaker. I have a 1982 Albin 40 so… queue the problem…. When I go to turn the main breaker on to my AC panel, it trips the shore power pedestal even though no other breakers are closed on my panel. Can someone tell me where to start troubleshoot? Maybe this will give me a good chance to rewire the boat….

Click to expand...

All breakers are off leaving ground and neutral connected somewhere on the boat tripping pedestal. The isolation transformer eliminated that, but you still have the two connected somewhere. Inverter or main panel buss bars?
Should it be left that way?

Soo-Valley said:

All breakers are off leaving ground and neutral connected somewhere on the boat tripping pedestal. The isolation transformer eliminated that, but you still have the two connected somewhere. Inverter or main panel buss bars?
Should it be left that way?

Click to expand...

The tripping breaker was the symptom, not the root problem. And adding an isolation transformer, though a good thing all around, has simply covered up the root problem.


With the iso transformer in place, you still need the onboard neutral and ground bonded at all times, and bonded in one and only one place. There are basically two ways to do this.


1) Bond at each power source, and make sure that each source's bonding only carries through to the rest of the boat when that power source is selected. This is probably the most common approach, but you really need to think it through carefully, one power source at a time, to be sure you are always bonded when using that power source, and not double bonded when using another power source. Inverter/chargers can be tricky because sometimes they are power sources, and sometimes they are not.


2) With an isolation transformer, your power source is ALWAY onboard, and your bonding is ALWAY onboard. In this case you can permanently bond in one single central location.This is much simpler, much easier to get right, and conversely much harder to screw up. Bonding is typically done at the main power panel.