Electrical plug in question

[Comodave]

My understanding - based on a 2019 club cruise to a brand new marina, two nights of 90+ degree weather with no dock power - is that the limit on a slip GFI is now 30 ma and the entire branch/dock is 100ma. Many/most boats will be ok w the 30 ma limit, but many/most combinations of boats will trip the 100ma GFI. On my 2007 Mainship, had to replace the galvanic isolator and fix a couple of wiring issues. Done by marine electrician. Fortunately done the prior year to address issue at home slip, so I wasn't part of the problem.

I am reasonably competent with household wiring. I do not work on boat 120V wiring. Complexities of shore power, generator, inverter, grounding, etc. And the risk is too large - even if everyone on the boat is safe, you risk anyone in the water. Hire a marine electrician if you are not expert and experienced.

There is 2 ways they are wiring docks. Either at the slip with 30 mAmp breaker or the whole dock with 100 mAmp breaker. It isn’t a combination of both. It is one or the other.

 

[Comodave]

Agreed, I'll be hiring a pro. Moved the boat to another slip though this weekend. I think there might be an issue with the power pole. I had the main breaker off no power going to any system on the boat and it still tripped. I only had the power plug plugged in. I am the first boat in this section of the marina so not sure if they need to double check things on their side. I'll report back.

Yes, my boat did that also before I replaced my main electrical panel and split the neutrals out so that they were not comingled together. It would trip both of my 30 amp breakers on my dock just by plugging the boat in without anything on the boat powered on. Not sure what exactly caused this because I fixed all the problems I found, don’t know which thing was causing the breakers to trip without any load but they did. I suspect that your boat does have a problem.

 

[Waywego]

A really excellent reference for boat electrical systems can be found at https://gilwellbear.wordpress.com/category/boat-technical-topics/electrical-topics/. If you are looking for a particular subject, check out the table of contents on the right side of the page.

 

[garychurch]

Sounds like you are shorting out the electrical connection. I had similar problem with a 50 amp shore power to boat chord. the chord was 15 years old and water had intruded into the wires through the plug end. These wires were badly corroded, overheating and tripping the breakers.

If your shorepower cable is not new I suggest you carefully inspect the plug ends as well as the initial 12” of wire for corrosion, including broken wire strands. If you find corrosion you may be able to cut away the corrosion and replace the plug ends as opposed to buying a new cable.

Good luck.

 

[DLaNeve]

Step 1.

This may be a very easy problem. Simply unplug EVERY electrical device you have that has a 3 prong plug. Lamps, toasters, refrigerator, blow dryer. Don’t forget the less obvious! For example; do you have an AC search light?

I’m betting one of these devices is the issue.

 

[Comodave]

This may be a very easy problem. Simply unplug EVERY electrical device you have that has a 3 prong plug. Lamps, toasters, refrigerator, blow dryer. Don’t forget the less obvious! For example; do you have an AC search light?

I’m betting one of these devices is the issue.

I don’t think so. He has the breakers off so these items are essentially non existent to the shore power. It is more likely some basic wiring issue such as a neutral to ground connection in the boat.

 

[sunchaser]

Don't overlook the inverter/charger as an issue. Insure the inverter is turned off when plugging in. The best insurance though is an inverter bypass.

 

[DLaNeve]

I don’t think so. He has the breakers off so these items are essentially non existent to the shore power. It is more likely some basic wiring issue such as a neutral to ground connection in the boat.

Turning off the breakers only disconnects the hot side. We are looking for a short between neutral and ground. Trust me, I’ve been down this road!

 

[Comodave]

He said he has the main breaker off which, if it is the proper breaker, will turn off the hot and neutral legs. The main breakers should be 2 pole breakers that interrupt both hot and neutral. I agree that he probably has a neutral to ground short but if the main breaker is off there should be no connection between the hot and neutral to the power cable.

 

[sapelo son]

Hubell Marine Voltage regulator with Boost

We had this problem, and a few more, all at the same time and as it turned out, for different reasons! (a whole pack of gremlins got loose all at the same time!) This was a couple of years ago at Ft Pierce while we were loading up to go to the Bahamas. Spent a couple of days trouble shooting and finding all kinds of little problems but, still not a complete fix. We decided to put it off at the time. Fast forward to just a few weeks ago and it surfaced again. Decided to pick up where we left off and after a day of chasing things, we decided to put in an isolation transformer with "boost"...… all better now plus, fixed the "fluctuating voltage" problems at other less stable ports...…

 

[Comodave]

I found multiple problems with my boat and a friends boat. So it is difficult to say which problem fixed which symptom.

 

[bshillam]

Just to be on the safe side though and to make sure it's not a shore power cord issue, I'll be closely inspecting. The prongs did have some corrosion, cleaned up, then used some dielectric grease. I'll also be checking on the galvanic isolator. Once our marine electrician is back though I will put him on the job.

 

[Rich wilmer]

GFI sences current in milli amps between the neutral and ground if your grounds aren't isolated from the neut. Youl be getting false trappings. Next thing to check is your battery charger. just staying

 

[ranger58sb]

Agreed, I'll be hiring a pro. Moved the boat to another slip though this weekend. I think there might be an issue with the power pole. I had the main breaker off no power going to any system on the boat and it still tripped. I only had the power plug plugged in. I am the first boat in this section of the marina so not sure if they need to double check things on their side. I'll report back.

I've been slow to chime in...

On our way north, we stopped at Fernandina Harbour Marina for four nights. Since they'd been essentially wiped out, rebuilt, and only newly opened, I thought we were home free when our shorepower worked... on what I would have thought were the new GFCI pedestals.

Au contraire, apparently. Our next marina stop was Golden Isles on St. Simon's Island; shorepower tripped at the pedestal -- with all subordinate AC breakers (i.e., except the main panel breaker) and our inverter/charger OFF. Rats.

Our next GFCI-related opportunity was at Harborwalk Marina in Georgetown, where they have both new and old pedestals in various sections of the marina. Ditto we tripped the GFCI breaker as above. Rats (again). Moved to an older dock section, all good. (A couple years ago, we had an opportunity to try the new dock there, but when questioned and we said we hadn't been on one before, the dockmaster there just automatically assigned us to the older area...)

Everywhere else, our system has worked fine.

As we passed through Southport next, I was able to schedule a consult with one of Zimmerman's electricians. Without exhaustive hands-on, his first trial diagnosis is that our inverter/charger case ground is tied too closely to the bonding system (it's grounded on an engine block)... and he suggested we first try moving that to a common ground buss or even to that battery bank ground.

We didn't actually try that at the time, since it would have taken some significant "household" disruption to clear access to where that ground is. Given that we were just trying to get home before potential COVID-19 related lockdowns or whatever... I put that on my "to do" list for when the smoke clears now that we're home.

But I liked the suggestion to try the easy fix first, since in his experience tracing the issue can be more difficult than actually fixing it.

-Chris

 

[sunchaser]

Au contraire, apparently. Our next marina stop was Golden Isles on St. Simon's Island; shorepower tripped at the pedestal -- with all subordinate AC breakers (i.e., except the main panel breaker) and our inverter/charger OFF. Rats.

As we passed through Southport next, I was able to schedule a consult with one of Zimmerman's electricians. Without exhaustive hands-on, his first trial diagnosis is that our inverter/charger case ground is tied too closely to the bonding system (it's grounded on an engine block)... and he suggested we first try moving that to a common ground buss or even to that battery bank ground. -Chris

Your inverter was off but likely not the charger unless you have a bypass switch. As the Z guy noted, check out the inverter/charger. One of the smartest marine electricians I know on this subject says he has avoided the install of an IT on many older vessels by addressing the overall vessel grounding/neutral issues especially around inverters. Not all inverter/chargers (especially plus 5 years old) have an adequate internal transfer "relay" when hooking up to newer GFCI docks, another reason for a bypass switch.

 

[twistedtree]

Yes, my boat did that also before I replaced my main electrical panel and split the neutrals out so that they were not comingled together. It would trip both of my 30 amp breakers on my dock just by plugging the boat in without anything on the boat powered on. Not sure what exactly caused this because I fixed all the problems I found, don’t know which thing was causing the breakers to trip without any load but they did. I suspect that your boat does have a problem.

I'm curious about your case, not because I disbelieve it in any way, but because I don't understand how this was causing a problem.


Can you tell me what model inverter you have? I have a theory that it relates to the inverter bonding neutral and ground on the output side, and would like to look into it.

 

[ranger58sb]

Your inverter was off but likely not the charger unless you have a bypass switch. As the Z guy noted, check out the inverter/charger.

I don't have a bypass switch, and I think you're likely correct.

Now that I think of it, I can test for that, though. I believe I thought -- at the time -- that the (inverter) charger wouldn't start charging until we turned on the main AC panel breaker. But that would also mean the charger function would "instantly" begin as soon as the main panel breaker was turned on... so there would have been at least one load present...

Thanks for the tip. I'll have a look when I can next go over to the boat...

-Chris

 

[tiltrider1]

Neutrals from inverter supported loads can not be commingled with neutrals from non inverter supported loads. It has to do with the inverter bonding relay not being as fast as the ELCI/GFI switch.

 

[83GB]

Shore GFI problem

I had problems with tripping a GFI... I FINALLY traced it to the hot water heater. I had never replaced the 30 year old heating element or cleaned the inside of the tank. When I started doing maintenance, the element was a giant mess of deposits. Inside of tank had quite a bit of scale. I suspect the element was "shorting" to the "green ground" side of the hot water heater housing through the scale on the element. I would not have thought scale would conduct electricity but a new element installed and problem went away...

 

[Comodave]

I'm curious about your case, not because I disbelieve it in any way, but because I don't understand how this was causing a problem.


Can you tell me what model inverter you have? I have a theory that it relates to the inverter bonding neutral and ground on the output side, and would like to look into it.

We don’t have an inverter. I know it is strange but we would trip both GFI 30 amp 6 mAmp breakers just by plugging in. I have home style GFI breakers on my dock. I understand that the difference is that the home style trip at 6 mAmps instead of 30 mAmps like the marine breakers. I don’t see this as an issue but rather a good thing, if I can plug into a 6mAmp breaker I should be good on a 30 mAmp breaker. And so far this has held true. Since i replaced my main panel and reworked the neutrals I have not tripped my home breakers or at any marina that has GFIs on the docks. Mine would trip just by plugging the cables into the dock with the main breaker off in the boat. I think that the reason for this was President put 2 30 amp inlets in the boat. But they only had 1 30 amp main breaker in the main panel. The 2nd 30 amp inlet was wired directly into the bus for hot and neutral. So that shore power didn’t have any over current protection at all. Not correct at all. I have seen this on 2 other Presidents and even on a couple of Carvers. So I replaced the whole panel with a Blue Seas panel that has 2 30 amp main breakers. President wired all the neutrals on to 1 bus. I had to ring out all of the neutrals to find out which one went to which inlet. I added a second neutral bus bar and now I don’t trip on my home dock or any GFI equipped commercial dock. I have worked on several other boats that tripped the GFI dock breakers. Most of the problems have been due to neutrals being all connected to 1 bus bar. One of the boats had an outlet with the green and white wires switched so all the return current was on the ground wire instead of the neutral.

 

[83GB]

Shore GFI problem

hmmm... my boat sits out back of my house. It has a single 125/250 VAC inlet on the side of the boat. I have a 15 year old marine shore power pedestal on my dock; it does not have the new GFCI breakers. Anyone have any ideas how I can add one?

 

[Comodave]

What size breakers are in the power pedestal? If it is 30 amp then I used a household 30 amp GFI breaker. It cost in the neighborhood of $40. You can use a marine GFI breaker, they cost in the neighborhood of $400. The differences as far as I can tell is that the household version trips at 6 mAmps and the marine version trips at 30 mAmps. I got mine at an electrical supply shop.

 

[83GB]

I have a Newport Harbor Mate Power Pedestal that is about 15 years old. It has a single 50 amp 125/250 VAC, a single 30 amp 125 VAC and a dual 20 amp 115 VAC outlets. It has phone and ethernet connections. I use the 50 amp 125/250 VAC outlet for my boat; I do not use the 30 amp 125 VAC outlet.. Internal to my boat, I have two 50 amp circuits; one circuit is for three air conditioners and the other 50 amp circuit is for all other 115 VAC loads. Not sure what to buy or how to install a GFCI considering the 50 amp 125/250 VAC is two hots, one neutral and the green ground.

 

[twistedtree]

We don’t have an inverter. I know it is strange but we would trip both GFI 30 amp 6 mAmp breakers just by plugging in. I have home style GFI breakers on my dock. I understand that the difference is that the home style trip at 6 mAmps instead of 30 mAmps like the marine breakers. I don’t see this as an issue but rather a good thing, if I can plug into a 6mAmp breaker I should be good on a 30 mAmp breaker. And so far this has held true. Since i replaced my main panel and reworked the neutrals I have not tripped my home breakers or at any marina that has GFIs on the docks. Mine would trip just by plugging the cables into the dock with the main breaker off in the boat. I think that the reason for this was President put 2 30 amp inlets in the boat. But they only had 1 30 amp main breaker in the main panel. The 2nd 30 amp inlet was wired directly into the bus for hot and neutral. So that shore power didn’t have any over current protection at all. Not correct at all. I have seen this on 2 other Presidents and even on a couple of Carvers. So I replaced the whole panel with a Blue Seas panel that has 2 30 amp main breakers. President wired all the neutrals on to 1 bus. I had to ring out all of the neutrals to find out which one went to which inlet. I added a second neutral bus bar and now I don’t trip on my home dock or any GFI equipped commercial dock. I have worked on several other boats that tripped the GFI dock breakers. Most of the problems have been due to neutrals being all connected to 1 bus bar. One of the boats had an outlet with the green and white wires switched so all the return current was on the ground wire instead of the neutral.

I see, so you have two 30A shore cords, and their neutrals were commingled on board. I see how that would be an issue.

 

[twistedtree]

Neutrals from inverter supported loads can not be commingled with neutrals from non inverter supported loads. It has to do with the inverter bonding relay not being as fast as the ELCI/GFI switch.

That makes sense. So in that case, the root problem is a bonding switching scheme that doesn't quite work with ELCIs.

 

[sunchaser]

Neutrals from inverter supported loads can not be commingled with neutrals from non inverter supported loads. It has to do with the inverter bonding relay not being as fast as the ELCI/GFI switch.

 

[Comodave]

I have a Newport Harbor Mate Power Pedestal that is about 15 years old. It has a single 50 amp 125/250 VAC, a single 30 amp 125 VAC and a dual 20 amp 115 VAC outlets. It has phone and ethernet connections. I use the 50 amp 125/250 VAC outlet for my boat; I do not use the 30 amp 125 VAC outlet.. Internal to my boat, I have two 50 amp circuits; one circuit is for three air conditioners and the other 50 amp circuit is for all other 115 VAC loads. Not sure what to buy or how to install a GFCI considering the 50 amp 125/250 VAC is two hots, one neutral and the green ground.

I am not familiar with the 50 amp GFIs since my boat is 30 amp based. You will probably have to go to an electrical supply shop and get ready to pay for this one... The NEC has changed again and now requires GFIs on private docks. Yours is probably grandfathered in as is but it is safer to go with the GFIs.

 

[Comodave]

I see, so you have two 30A shore cords, and their neutrals were commingled on board. I see how that would be an issue.

Most boats from that era are probably commingled also. I looked at a Carver from the 80s because they couldn’t plug into GFI docks. Theirs was commingled also and only had 1 main breaker for 2 inlets. There is going to be a lot of work for marine electricians in the next few years...

 

[sunchaser]

hmmm... my boat sits out back of my house. It has a single 125/250 VAC inlet on the side of the boat. I have a 15 year old marine shore power pedestal on my dock; it does not have the new GFCI breakers. Anyone have any ideas how I can add one?

Heresy I know, but why would you need one? I know, drownings shock and the dangers etc. But, are those prevalent issues or just new codes looking for an excuse to be written. Naturally if your wiring is giving issues and in bad shape, suggest you carry through with your plan.

I've had several conversations with BC Hydro on their marine installations Vs the new US codes. Some puzzlement exists.

The most experienced dock divers on Vancouver Island say they've tested every marina there with no shocking issues found. That said, I'm waiting for a new marina in the Victoria Harbor to fill me in on their approach. I'll have to wait a few months.

 

[Comodave]

How can they test every marina? Boats come and go, and the ESD is an issue with a particular boat not a marina. And it is mostly a problem with fresh water not so much in salt water.