Dock Circuit Breaker Trips

[Dehli]

Hello, I'm trying to debug an electrical issue I'm experiencing on my Sea Ray Express Cruiser 340 (1985). I have it hooked up to shore power and the dock's circuit breaker will randomly trip (sometimes it takes a few hours before it trips).

I have unplugged everything near the boat's batteries, and I've progressively switched everything off on the boat until it stopped tripping the dock's circuit breaker. It seems to be related to the 30A A/C main switch on the boat. If I only have that on it will trip the dock, but when I switch it off it won't.

I have also discovered that by switching the master switch to off while the 30A A/C main switch is on, it will consistently trip the dock's circuit breaker. I have uploaded a minute long video better showing this:

I am not using an extension splitter, just have one cord plugged directly into the main plug (not using the Air Condition side).

My first thought it to replace the main breaker but I'm wondering if there are any other tips or suggestions for what I should try?

Thanks in advance for any help!

 

[ttmott]

What kind of a circuit breaker is the dock breaker?
Standard single pole or a ground fault device?

 

[Dehli]

Hi @ttmott, thanks for your help! I'm pretty sure it's a ground fault device. I attached a picture of the dock breaker. Let me know if I can answer anything else about it!

 

[Skybolt]

... I attached a picture of the dock breaker. Let me know if I can answer anything else about it!

Yes that is a GFCI breaker.

How long have you had the boat in that slip using that stanchion?

It sounds like you have an issue with the boat. The AC coming into the boat is probably fine, somewhere in the the boat there is an issue. If you turn off the main and all breakers, keep the boat set to the shore power, both 1 and 2. The reset the stanchion breakers, if one pops then that leg of the feed possibly has a neutral and ground swapped.

If nothing pops in that condition, then turn on the main only. Then one breaker at a time.

BTW, you mentioned you turned off everything by the batteries, anything DC should not have anything to do with this.

 

[ttmott]

Most likely one of your boat's circuits are leaking to either ground or to the water. It doesn't take much like between 5 and 30 milliamp leakage.
Some older boats bond the neutral to the boat's bonding system and ground - that will trip a ground fault every time. Typical devices that are culprits ate AC compressors, water heaters and refrigerator compressors.
To test run one circuit at a time until the one that trips the GFI is found.

 

[Dehli]

Thank you both!

I've had the boat here for ~2 years and it's been occurring since I had it here. I have brought it to another dock and it also tripped there so it's definitely a problem with the boat.

Makes sense that nothing by the batteries would be causing this! Won't mess around with anything down there. I tried Googling for what stanchion breakers were but couldn't find anything. Are those the dock breakers?

On the boat's panel, when I have everything off except for the 30 AMP AC Main (like what's in the below picture), it will trip when I leave the boat for an hour or two. If I start switching them on one at a time they don't consistenly trip the breaker. The only way I have been able to get it to consistently trip is by doing what I did in the video above.

Is there some other way I should be testing the circuits than switching them on at this board?

I assumed that nothing should be pulling juice when it's just the main that's on.

 

[Skybolt]

Those breakers are 30A GFCI breakers that usually trip @30ma of reverse current. This can happen when the neutral and ground are tied together somewhere in the boat.

It sounds like you don't know how or what a GFCI breaker is? It is a ground fault circuit interrupter. It will trip if the Neutral and Ground are connected together somewhere. It doesn't have anything to do with pulling to much current.

 

[K-DUB]

I have friends that have boats of that vintage and the generator was the culprit. The ground and neutral were tied together like Skybolt said. They separated those and all was good.

 

[Dehli]

Thanks for explaining @Skybolt! That makes sense, I didn't know that. Will see if I can find where a ground and neutral are tied together!

Will check the generator first, thanks @K-DUB!

 

[Skybolt]

Thanks for explaining @Skybolt! That makes sense, I didn't know that. Will see if I can find where a ground and neutral are tied together! ...

The generator will have the neutral and ground connected because it is a source, which is an ABYC standard. The area to look is at the panel, usually in the older boats the neutral and ground tied are together. The generator neutral should be switched with it's hot leg to properly isolate the feeds.

If you don't have a gen/shore power switch that lifts the neutral, a new switch may be needed. To test, unplug the shore power, leave the panel switched to shore. Open the panel and put a meter across the shore neutral and generator neutral to check.

 

[ttmott]

The generator will have the neutral and ground connected because it is a source, which is an ABYC standard. The area to look is at the panel, usually in the older boats the neutral and ground tied are together. The generator neutral should be switched with it's hot leg to properly isolate the feeds.

Hey Orlando - keep in mind that some older boats did not switch the neutral as required today. @Dehli 's boat appears to be 1985 vintage which may not switch them out. However, in all GFCI installations the minute he turned anything on that routed current to the ground it would have tripped the circuit breaker; so I suspect it does switch the neutrals if the boat has a generator. He did not mention if the boat has an inverter which if installed wrong will do the same thing.
He seems to be able to plug in the boat then the GFCI trips randomly and has done that for some time and not necessarily attributed to any single circuit on the boat. My first approach, as you iterated is to progressively step through the boat's circuits to find the criminal. My gut says battery charger.....

 

[Skybolt]

Hey Orlando - keep in mind that some older boats did not switch the neutral as required today. @Dehli 's boat appears to be 1985 vintage which may not switch them out. However, in all GFCI installations the minute he turned anything on that routed current to the ground it would have tripped the circuit breaker; so I suspect it does switch the neutrals if the boat has a generator. He did not mention if the boat has an inverter which if installed wrong will do the same thing.
He seems to be able to plug in the boat then the GFCI trips randomly and has done that for some time and not necessarily attributed to any single circuit on the boat. My first approach, as you iterated is to progressively step through the boat's circuits to find the criminal. My gut says battery charger.....

Yep mentioned the generator in my last post, I had an 86 340 that had all of the neutrals tied together even though it was dual thirties. The shore switch was only switching the hot legs. What a mess. In this boat I also had a rotary switch go bad and took out the generator windings also. In replacing both I put in a triple breaker slide switch when I made the new panel. That was an expensive repair.

Agree that it may not be that the panel, but the basics need to be ruled out first, IMO. But to your point, that vintage had the promariner chargers that had everything tied together. So you could very well be on to something.

 

[Dehli]

Appreciate the discussion! It's definitely helping me understand a lot more of this. Additionally, I don't have an inverter on the boat.

When you say to "progressively step through the circuits" what do you mean? Would I unplug them from the panel itself. If so, how is that different from just switching them off on the panel?

Thanks again!

 

[ttmott]

Progressively meaning one at a time. First a detailed inspection and (what I do) is make a schematic of the boat's wiring. Even corrosion can shunt current to ground. There were a couple of contributors that noted corrosion on the boat's side of the shorepower connection (behind where the boat wiring terminates) and how that ended up being a short to ground and overheating at that connector.
Then after validating all of the incoming wiring is good go through each of the circuits on the boat's panel. Start with everything turned off and breakers off. Then one at a time activate a circuit and one at a time power up things on that circuit. Validate it's operations. Then turn that circuit off and move on to the next - same thing.
Make sure things on that circuit get powered on and is operating. For example, turning on the air conditioning power is not testing that device unless the A/C is up and running.

 

[Skybolt]

@Dehli one thing not explained that you may not know, only the hot legs of the AC are through breakers. All of the neutrals are just tied together on a "Neutral" bus bar(s). that is how the GFCI breaker can pop without any of the breakers being on.

 

[Dehli]

Thanks @ttmott! Will go through and make a schematic so I have an internal understanding of how all the circuits are connected. Great tip!

@Skybolt That's had me stumped! I've been confused as to how the breakers are all off and something that's "off" could be causing it to trip. Thanks so much for offering that explanation! I'll try to find the bus bar as well as I go through making the schematic.

 

[Dehli]

Could I unplug each of the circuits (one at a time) from the neutral bus bar and its hot leg to figure out which circuit is the one causing it to trip?

 

[PlayDate]

Okay ...... I agree with what @Skybolt and @ttmott have said but the video actually shows something different.

It seems to only consistently trip the dock GFCI when the 30 amp breaker is left on. All the other breakers are off. If he leaves the AC Main 30 amp breaker in the off position when turning on shore power and then switches the 30 amp breaker on.....it works fine. In the video he cycles the 30 amp breaker several times and the GFCI does not trip.

So why does it trip the GFCI when the 30 amp switch is on when he turns the rotary shore power switch? You would think that cycling the 30 amp switch would introduce the same issue.

I agree that it is probably a neutral/ground issue. That said.....I would really like to put a DVM on the leads behind that panel and see what the GFCI is seeing.

 

[hughespat57]

Tracking down a small leakage current can be a real PITA. Be patient and keep track of each circuit you work one at a time.

Given the age and it seems to be repeatable I would try a simple item first. The “Reverse Polarity” light. This light is intentionally connected to Neutral and Ground.

Newer boats use an LED and a resistor that will not trip GFCI.
Older boats used a Neon lamp that does not light unless Hot to Ground is about 90v. And normally will not trip.

Some really old boat just had an incandescent pilot light. The filament could pass enough current to trip a GFCI.
Disconnect one wire of the RP light and do your test again.

 

[hughespat57]

Just an FYI
That pedestal breaker is a Class A
Thats 5ma trip that can be very difficult to stay under on an older boat.
By NEC the pedestal should be a GFPE rated at 30ma.