Dock Circuit Breaker Trips

[ttmott]

Almost same, but I would remove the green at the block, just because its easy and that will remove the coil AND the pilot light for RP.
He has a combined power and RP lamp assembly so the lamp would still be in play since it has its own White.

Yes, but I'd do one at a time to isolate exactly the issue.

 

[Dehli]

Another update: I did what both of you all recommended and it's still resulting in the dock's GFCI tripping. I first waited to see if it would trip on its own (with the wire disconnected) and it took about 15 minutes before it finally did (only having the 30 AMP A/C main turned on). Second time I did what was on the video I uploaded to make it trip faster.

 

[Dehli]

Also is there any documentation I can provide for recommending 30mA breaker instead of the class A?

 

[PlayDate]

https://www.eaton.com/content/dam/eaton/products/low-voltage-power-distribution-controls-systems/marina-power-lighting/resources/beginners-guide-mpl-brochure.pdf

NEC 2017, Section 555.3 for ground fault protectiono New to the 2017 National Electrical Code: “The overcurrent protective devices that supply the marina,boatyards, and commercial and noncommercial docking facilities shallhave ground-fault protection not exceeding 30mA”


Latest update:

https://thenecwiki.com/2021/02/article-555/

1. Ground-Fault Protection. The overcurrentdevices that supply the marina, boatyards, and commercial and noncommercial docking facilities shall have ground-fault protection not exceeding 30 mA.

5 mA is way too sensitive. I would check the other nearby pedestals to see what they have.

 

[Dehli]

Thanks! I checked the one beside my boat and it's also 5mA . Will reach out to the manager with the above and hopefully they can make the change pretty quickly.

What I plan on doing next is to go through the circuits that I have circled and disconnect one at time from the bar. Hopefully I can isolate which circuit has neutral & ground touching.

Let me know if that doesn't sound like a good approach, haha.

 

[ttmott]

I just picked up that the breaker is tripping when you switch the main shorepower/generator rotary switch.
Soooo -
There is a distinct possibly that when rotating the rotary switch the neutrals get combined during the transfer before complete disconnect from the Shore.
Now that I've seen the video in your first post again if you switch the shorepower rotary switch with the main breaker on it trips. Seems quite possibly an issue with the rotary switch.

 

[Dehli]

Awesome! Will investigate that too. FYI, that's a way I can trip it consistently but it also trips (after ~15 minutes) if I just leave it alone keeping it on shorepower (with just the A/C main switched on) - don't have to touch the rotary switch to make it trip.

 

[ttmott]

Awesome! Will investigate that too. FYI, that's a way I can trip it consistently but it also trips (after ~15 minutes) if I just leave it alone keeping it on shorepower (with just the A/C main switched on) - don't have to touch the rotary switch to make it trip.

If it makes sense - there is a phenomenon called inrush current. Switching a dead circuit into a live circuit there is a current surge called inrush which could easily exceed that 5ma.

The bottom line here is you want zero leakage from the boat to ground or to the water. So, to install a 30ma device still doesn't fix the issue.

 

[PlayDate]

My esteemed colleagues of @ttmott @Skybolt and @hughespat57 know more than I do regarding what you are dealing with.

That said......a lot of marinas have had issues with older boats and their new pedestals.

The simple issue is that you are tripping a very sensitive GFI. The easy solution is to buy a new GFCI (30 mA) and have the marina install it. Our marina (their Marine Electrican) has replaced several GFCIs (30 mA) and the pedestals are only 5 years old that kept tripping with the de icers on. Once the GFCI was replaced....none have tripped since.

If it works.....everyone is happy and can enjoy Thanksgiving. I am not saying all the diagnostic advice is problematic....but since all we know is the GFCI is tripping and we don't know exactly why......what is wrong with a Plan B?

Who is the manufacturer of the Pedestal and what model number is it?

 

[Dehli]

If it makes sense - there is a phenomenon called inrush current. Switching a dead circuit into a live circuit there is a current surge called inrush which could easily exceed that 5ma.

Very possible. And since switching the 30 AMP A/C main back and forth doesn't cause it to trip makes me think that there could be an issue with the rotary switch.

@PlayDate Totally agree! Appreciate all the advice as it's helping me learn a lot about how all of this stuff works. I reached out to the manager an hour ago so hopefully I get a call or email back soon.

I think the pedestal is a Murray LW004NR Model 21 Type 3R (I uploaded a picture of it here https://clubsearay.com/index.php?threads/dock-circuit-breaker-trips.114921/post-1439997).

 

[PlayDate]

And just for precision: The breaker in the box is a MP GT has the following description:

1. Murray Type MP-GT 2-Pole ground fault circuit interrupter with a trip range of 6-Milli-Amps has non-interchangeable thermal magnetic function for reliability. It is rated at 30-Amps and 120/240-Volts AC.

I believe it cross references to Siemens.....hopefully one of our experts can confirm that.

BTW is it the breaker on the left that keeps tripping?

 

[Dehli]

Thanks! They both trip (I've switched my shore power cable between both outlets and have experienced tripping with both).

 

[PlayDate]

Thanks! They both trip (I've switched my shore power cable between both outlets and have experienced tripping with both).

The one on the left looks like it has had a lot of reset activity.

 

[Skybolt]

Thanks! I checked the one beside my boat and it's also 5mA . Will reach out to the manager with the above and hopefully they can make the change pretty quickly.

What I plan on doing next is to go through the circuits that I have circled and disconnect one at time from the bar. Hopefully I can isolate which circuit has neutral & ground touching.

Let me know if that doesn't sound like a good approach, haha.

The dockside breakers definitely need to be replaced with the correct type as @PlayDate has stated. That could be attributing to the issue as John has mentioned.

Pulling the green ground wires is not the way to check this. The green grounds should all be tied together and not tied to any breaker.

The way a GFCI works is the current draw is balanced between the neutral and hot. If they are not equal within the 30ma then the breaker trips. It will also trip if the ground and neutral are tied together. It will also trip if the current draw is over the rating of the breaker.

I am confused on a this, you have twin 30's feeding the boat, but the panel only has a single 30A main breaker. Where is the main breaker for the the other 30A line?

You also say the breaker trips ~15min of being on. Is this with the entire boat turned off? Only the main breaker on? The only way that can happen is with current draw or the breaker is defective. If there is anything on when the breaker trips?

 

[PlayDate]

@Skybolt

I too share some confusion over the GFCI tripping over time. Is it possible that this problem and the condition of one of the shore breakers (lots of resets) could mean that there is stray current in the water?

6mA is not a lot of current. Is it possible the boat is just part of the problem? This is not my area of expertise.

The reason I ask is that I went back to the first post and this appears to be a new marina for @Dehli and a new problem. If that is the case, I just wonder based on the condition of the left breaker if we are chasing our tails and the problem is external to the boat.

 

[Skybolt]

@Skybolt

I too share some confusion over the GFCI tripping over time. Is it possible that this problem and the condition of one of the shore breakers (lots of resets) could mean that there is stray current in the water?

6mA is not a lot of current. Is it possible the boat is just part of the problem? This is not my area of expertise.

The reason I ask is that I went back to the first post and this appears to be a new marina for @Dehli and a new problem. If that is the case, I just wonder based on the condition of the left breaker if we are chasing our tails and the problem is external to the boat.

Couple of things. The dock breakers are definitely in question, to your original point. That was mentioned earlier and then brushed over, but still remains an issue.

Stray current in the water is an issue for many things. But the way a GFCI breaker(s) works is it tracks the current draw through the neutral and hot, they need to be equal +/- the 30ma reverse current tolerance. They don't monitor or look at the ground. If there is an imbalance it is assumed that current is returning via the ground. So outside current not supplied from the breaker itself will not necessarily trip the breaker. Large voltage changes will cause an issue and pop breakers but I would think other pedestals would be effected as well.

I would like to know the answers to my questions in my last post. Twin 30A feeds and only one 30A breaker. How is the AC/Heat connected and where is that main breaker?

If the dock breaker pops with the boat connected and everything off after 15 minutes then it should do that with the boat unplugged. If it doesn't then the boat is drawing current and other things are on in the boat.

 

[Dehli]

Thanks you all! Just got back from the boat and I've got a good update!

Your question about the second breaker made me start looking for another breaker and I found it on the side of the panel (picture attached and video here). It was in the on position so I shut it off and ran through my tests and the dock's breaker didn't trip . I can switch the rotary back and forth without the dock tripping like before. Additionally I stayed on the boat for 20 minutes without it tripping. I'll go back in a few hours and check if it's tripped, but fingers crossed that it doesn't.

To answer your other questions, there are twin 30's that could lead into the boat. The previous owner of the boat had a splitter but I stopped using it to eliminate that variable. I only have one cable going into the main plug (don't have anything plugged into the air conditioning side). I could pick up another cable if you think that would be helpful but I don't use the air conditioning while I'm on shore power so I hadn't picked it up yet.

Nothing is on in the boat (that I'm aware of) when it's tripping (other than the air conditioning breaker - which is now off).

Will report back in a few hours with whether it's tripped or not. If it doesn't, from my understanding there's a ground and neutral touching somewhere between the air conditioning breaker and the main panel?

Thanks again!

 

[Skybolt]

Thanks you all! Just got back from the boat and I've got a good update!

Your question about the second breaker made me start looking for another breaker and I found it on the side of the panel (picture attached and video here). It was in the on position so I shut it off and ran through my tests and the dock's breaker didn't trip . I can switch the rotary back and forth without the dock tripping like before. Additionally I stayed on the boat for 20 minutes without it tripping. I'll go back in a few hours and check if it's tripped, but fingers crossed that it doesn't.

...

I am guessing that second breaker is the main breaker that disconnect's both 30A incoming connections into the boat and is before the panel itself. With those in the off position I would think there is nothing that can be powered on. So the wiring of that breakers needs to be checked. It could also be that breaker is just for the AC?

Either way it looks like the boat is still being powered when the main panel is all off and why the breaker on the dock is tripping after a period of time. If possible, take a pic of the wiring for that breaker.

 

[Dehli]

Sure thing! Will go back to the boat and take some photos of that wiring and check if the dock has tripped. When the breaker on the side is in the off position, the main panel's showing voltage (when I have its main breaker on). Makes me think it might be just for the air conditioning side. Will try to follow the cables too to see how it's wired.

 

[ttmott]

Sure thing! Will go back to the boat and take some photos of that wiring and check if the dock has tripped. When the breaker on the side is in the off position, the main panel's showing voltage (when I have its main breaker on). Makes me think it might be just for the air conditioning side. Will try to follow the cables too to see how it's wired.

Do a drawing as you look into these things.
The main circuit breaker you found is a two-pole circuit breaker. 90% sure it protects both of the shorepower supplies.
One supply (hot and neutral) goes to one rotary switch and the other supply to the other rotary switch after that main circuit breaker.
The two grounds from the shore power should route to two galvanic isolators then from the isolators to the boat's grounding and bonding systems.
Each of the rotary switches switch separate and unique circuits between shorepower, off, and generator.
Each of the rotary switches must switch the hot and neutral legs from the shorepower.
Each of the rotary switches combine the neutral and boat's ground when in the generator position.
The generator is 120 VAC, consequently, both sides of the boat's electrical system are tied together when on the generator.
When not switched to the generator the two AC shorepower feeds must be completely separate and uniquely power separate devices. This is because it is likely the two shorepower feeds will be out of phase and will be a direct electrical short otherwise.

My head is still on an issue with the rotary switch(s).