Electrical Mystery

Sep 5, 2019
39
Hunter 386 Rock Hall
Had an electrical mystery that I need help with. When I plug my shore power into a 115 volt 15 amp plug it keeps blowing the ground fault breaker. I am using a 15 amp to 30 amp pigtail plugged into the shore outlet and then connected to my 30 amp shore power cord. When I connect to circuit B it works fine. When I plug into circuit A it blows. But here’s my mystery, everything is shut down on circuit A, there is no current draw to cause the breaker to blow. What’s going on? Do I have a bad ground on A or what?
 

SG

.
Feb 11, 2017
1,670
J/Boat J/160 Annapolis
Walt of Rock Hall,

You the shore side receptacles each have their own ground fault interupter "on the wall" or "on the box"? Or is it the breaker on the boat? Or is a ground fault breaker on the panel that is on shore?

First, I'd like to suggest that cut the DC load on the boat to NOTHING. Then try to see if the breaker that blows does it only when you load-it up with a minor load. Then I'd like you increase the load on the boat (like letting your charger do it's thing, or your little space heater, or whatever.)

Then I'd like to suggest that get a CLEAN extension cord with (say a hairdryer attached). Plug it into ease of the Shorepower outlets and see if the breaker trips.

We're trying to see where the issue is.
 
Jan 18, 2016
782
Catalina 387 Dana Point
Your clue is "Ground Fault Breaker" -- so there's 2 things that may trip it.

1. Overcurrent. It's possible that circuit A developed a dead short between the hot and neutral/ground before the breaker on the boat (in the wire from the shore inlet socket and the breaker on the boat) Then when you plug it in it'll pop. Generally if you plug in the boat, then throw the breaker to on, it'll buzz a good one as it's turning itself back off. (and if you plug it in hot, not recommended, it'll be a good poppin arc - you'll know about it.)

2. Ground Fault. There's a leakage between hot and ground somewhere between the inlet and the breaker on the boat. It doesn't take much leakage at all (5-20 milliamps) to trip. So you get some dirt or a loose piece of line or something between hot and ground on the inlet. Then it gets wet and conductive. Breaker trips. Or it may be chafe starting to get hot and ground shorted. Solution/DX is to start removing connections until it stops tripping. The "right" diagnosis is a leakage measuring clamp meter - but most folks don't have one of those.

GFCI's do go bad too. But since you mentioned that circuit B operates correctly, you've ruled that out.

Standard noise about not playing around with lethal levels of voltage unless you really do understand what you're doing. A marine electrician may be cheaper than boat flambeau , hospitalization, or a funeral.
 
Apr 12, 2007
175
Hunter 420 Herrington Harbor South
Check with the marina. If they have changed the breakers to comply with the new Maryland standards. You may be tripping the shore breaker at the main connection point not just the piling breaker. We / I had the same problem at Herrington Harbour when they redid the docks. Several of the older boats were tripping breakers when they reconnected to the new docks. I don't know what the new standard is or why they trip but it is something to do with the older isolators according to a surveyor. They have been seeing it at several places. I had the issue with my '03 386 :(just before I sold it. Fortunately, when connected to an older dock there was no issue so it wasn't an internal boat problem. Don't have the issue with my '05 420:clap:
 
Feb 6, 1998
11,665
Canadian Sailcraft 36T Casco Bay, ME
Had an electrical mystery that I need help with. When I plug my shore power into a 115 volt 15 amp plug it keeps blowing the ground fault breaker. I am using a 15 amp to 30 amp pigtail plugged into the shore outlet and then connected to my 30 amp shore power cord. When I connect to circuit B it works fine. When I plug into circuit A it blows. But here’s my mystery, everything is shut down on circuit A, there is no current draw to cause the breaker to blow. What’s going on? Do I have a bad ground on A or what?
It could be many things, but most often this is caused by an AC Neutral (White) to AC Grounding (Green) bond on-board the vessel when there should not be one if you are plugged into shore power. Best course of action is to hire an ABYC certified electrician who knows what he is doing.

Things that can cause this:

Improperly wired inverter
Improperly wired AC system
Dual Shore power systems with the neutral co-mingled
Appliances that bond neutral to ground
Incorrectly wire generator
Non marine battery charger

etc. etc.

I have posted the information below before, but it is still worth understanding..

While your boats leakage could be below 5mA it's not until another boat plugs into the same GFCI "circuit" that the GFCI trips because the cumulative leakage, on that GFCI feed, has now exceeded 5mA and causes the GFCI to trip.

Plugging a vessel into a 15A or 20A household receptacle is NOT proper shore power. This is problem #1.

Problem #2 gets a lot more complex.....

The current NFPA 70 / NEC requirements Article 555 Marinas & Boatyards, which rolled out in 2011, requires a 100mA ground fault protection level for marina dock feeds. In the upcoming 2017 NFPA 70 / NEC 555 this maximum level has now dropped from 100mA to 30mA. You are trying to plug your vessel into a 5mA trip level GFCI.

(Copy & paste of a previous reply)
The Problem With the New Mandates:

#1
NFPA 70 / NEC requirements do not mandate 100mA or 30mA protection at each dock pedestal, which would be the only prudent way to adopt or phase this into an entire industry where the safety standards are voluntary and arguably grossly ignored.

As I type this I am currently waiting for a customers phone to cool down so we can continue troubleshooting his shore system via video messaging. He is in the BVI and can't find a decent electrician to save his life. So far we've found on-board AC neutral bonded to AC Earth and his two 30A shore inlets have common neutral bonding. Somewhere in his travels he had a failed 8kW generator ripped out, by some hacks, who left a ghost transfer switch and ran the ghost wires to where ever they found an open terminal. It is a freaking mess, a mess I repeatedly tried to talk him into fixing before he headed off cruising, "seems to work" he'd say.... He began complaining of issues when his vessel began tripping up to code marina's and shutting entire docks down. The non-transients at these marinas were none too happy and the marinas finally told him not to plug in..

As a result of NFPA/NEC not requiring 100mA or 30mA ground fault protection at the pedestal level, for each boat, any vessel plugging into a dock pedestal that is protected by an upstream ground fault device can create nuisance trips for every boat on that same feed. This = BAD (safe, but bad)

Shore based ground fault devices that cover multiple pedestals (boats), can result in a nuisance trip that depowers all the boats on that string and create a lost power situation to all of those vessels, just as my customer has done, at no less than 3 or 4 marinas since leaving Maine.

This NFPA / NEC roll out has already cost boaters significant $$ in destroyed battery banks etc.. Unfortunately the boaters who lost out may not have been the ones who created the problem just the recipient of what I often refer to as Darryl & Darryl wiring, for those old enough to get the Newhart reference.. No offense to any Darryl's out there....

The new NFPA / NEC ground fault requirements for marinas is only serving to expose the horrendous wiring that has gone on in the marine industry for far too long. Even if your boat is properly wired, to ABYC standards, you can still suffer the consequences of Darryl & Darryl hack jobbing their own boat wiring because the NFPA/NEC requirement is not at the power pedestal/individual boat level.

For what it is worth I have very infrequently come across an owner who believed it was their boat creating the leakage or corrosion issues. In almost all cases it starts out as "someone else's problem" until the fault is found on-board...

#2 Far too many boats out there are not wired to meet or exceed the ABYC safety standards. The NFPA / NEC could really care less about this, it's not their issue. When you plug an incorrectly wired vessel into the new NFPA /NEC shore standards, requiring ground fault protection, it can now become everyone's issue not just the problem vessel. Incorrectly wired vessels create problems for everyone at an up-to-code marina.

Boats that are not wired to current ABYC standards, as a group, have very, very high ground fault percentages. For example the number of boats I measure with AC grounding (GREEN) and AC Neutral (WHITE) bonded on-board the vessel (A huge no-no) is in the range of 35-40% +/-. This is INSANE, but it is the reality of a voluntary standard that has gone largely ignored by boat owners, or DIY wiring done by local dock-experts who think they know more than the standards organizations, and far too many folks who call themselves marine electricians..

Bottom Line? Improperly wired vessels, vessels not wired to ABYC standards, can cause nuisance tripping of shore ground fault interrupters. This issue will be rarer at 100mA or 30mA and quite a common occurrence at 5mA...

The sheer age of many vessels also means some of them have equipment that is so antiquated that it too creates an inadvertent neutral to grounding bond on-board the vessel. Improperly wired inverters, generators, transfer switches, automotive grade battery chargers, auto grade inverters, improperly wired hot water heaters etc. are all hot button areas where a neutral/grounding bond may be hiding. Some boat owners & terrestrial based electricians have also been known to place a jumper between neutral and grounding bus.

#3 The Rx?

Marina Rx:
Marina's who want happy customers should ideally install a 100mA or 30mA ground fault device at each pedestal, not 5mA. The GF device (GF=Ground Fault) should be installed at each pedestal so one boat or transient can not take out an entire dock or entire group of vessels due to dangerous wiring practices. Adding a GF device at each pedestal is in compliance with NFPA 70 / NEC and actually exceeds the minimum requirements.

By installing a ground fault device at each pedestal, this prevents Darryl & Darryl's stellar wiring job from taking out your boat when they create a nuisance trip. These ground fault devices should not be daisy chained to the load side of the GFI and should serve only that pedestal.

Marina's also need to comprehend and understand that GF leakage is additive. If we have ten boats each leaking 4 mA, which is not even enough for each boat to trip an individual 120V 5mA GFCI, those ten boats together can trip a single 30 mA ground fault device.

Marina's should prohibit vessels that cause a nuisance trips, from plugging into their system, until the fault has been corrected. If a vessel is tripping a 100mA threshold device (and this is not due to additive leakage) this creates a very dangerous potential for electric shock drowning.

The issue & mess of nuisance tripping will only get worse now that the NEC has dropepd to 30mA. Why? Because the drop in mA trip leakage does not technically require protection at the individual dock pedestal level. Frustrating to say the least.

Marina's need to fully understand the new requirements and be trained on how to conduct spot audits and to check for individual vessel issues that would otherwise create problems for the rest of their customers. Or do it right and install a 30mA device at each pedestal, this way only the miswired customer is left without power..

When a marina is re-wired, or the wiring touched by a professional, they now need to become in compliance with the current shore based standards. The mandatory shore based NEC/NFPA standards extend to the dock pedestal receptacle, and the voluntary ABYC standards begin at the shore power cord set.

This problem of nuisance tripping is only going to get worse, much worse as time goes on and more and more marinas become in compliance with the NFPA 70 / NEC requirements. Once the code drops to 30mA, to protect multiple pedestals, it will become a complete debacle..



Boat Owner Rx:
Wire your vessel to the current ABYC standards and you will no longer create dangerous situations, power loss or dead batteries for those around you who do have properly wired boats.

Two Easy Tests for 120V 30A Service (these two tests barely scratch the surface but it's a start):

1-
Use a high resolution AC clamp meter set to measure A or mA. Extech, Yokogowa and Fluke all make excellent AC leakage clamp testers. Ideally every marina should own one. Power up your on-board AC devices (hopefully all of them) & place the clamp around your shore power cord. The reading should be 0.0A. Any reading above this is indicating an amperage imbalance between the hot and neutral AC conductors and indicating that this missing current is leaking elsewhere eg: into the water..

2- One of the easiest tests or starting points is to physically unplug your vessel from the pedestal and be sure your inverter is decoupled from DC so it does not auto-invert. Make sure any manual transfer switches are set to SHORE. Now test for continuity between AC WHITE/Neutral and AC GREEN/Earth/Grounding pins at the shore end of the cord or at your on-board grounding bus and neutral bus.. There should be no continuity.

If you find issues you are unsure of I would suggest bringing in a professional....
 
Sep 5, 2019
39
Hunter 386 Rock Hall
Check with the marina. If they have changed the breakers to comply with the new Maryland standards. You may be tripping the shore breaker at the main connection point not just the piling breaker. We / I had the same problem at Herrington Harbour when they redid the docks. Several of the older boats were tripping breakers when they reconnected to the new docks. I don't know what the new standard is or why they trip but it is something to do with the older isolators according to a surveyor. They have been seeing it at several places. I had the issue with my '03 386 :(just before I sold it. Fortunately, when connected to an older dock there was no issue so it wasn't an internal boat problem. Don't have the issue with my '05 420:clap:
Interesting. Unfortunately, I’m connecting to a decades old outlet on the side of a building in the parking lot where the boat is winter stored. i was able to run a power washer and a sander plugged directly into a the outlet. I could also power up and use circuit B. When I plug in circuit A, the breaker in the building trips. Circuit A is not powered up in the boat, the panel breaker is turned off. The main breaker under the port cockpit locker doesn’t trip. The only thing I can figure is that either moisture has gotten into the shore power A inlet or a ground wire is loose or corroded in the socket. Will be taking it apart this Friday.
since you did own a 386, I have another question. Did you have a generator installed? I’m trying to find one that will fit.
 
Apr 12, 2007
175
Hunter 420 Herrington Harbor South
since you did own a 386, I have another question. Did you have a generator installed? I’m trying to find one that will fit.
No generator

Marine Sail -- thanks for the article above. Checking begins Sat :) just to make sure.
 
Sep 5, 2019
39
Hunter 386 Rock Hall
It could be many things, but most often this is caused by an AC Neutral (White) to AC Grounding (Green) bond on-board the vessel when there should not be one if you are plugged into shore power. Best course of action is to hire an ABYC certified electrician who knows what he is doing.

Things that can cause this:

Improperly wired inverter
Improperly wired AC system
Dual Shore power systems with the neutral co-mingled
Appliances that bond neutral to ground
Incorrectly wire generator
Non marine battery charger

etc. etc.

I have posted the information below before, but it is still worth understanding..

While your boats leakage could be below 5mA it's not until another boat plugs into the same GFCI "circuit" that the GFCI trips because the cumulative leakage, on that GFCI feed, has now exceeded 5mA and causes the GFCI to trip.

Plugging a vessel into a 15A or 20A household receptacle is NOT proper shore power. This is problem #1.

Problem #2 gets a lot more complex.....

The current NFPA 70 / NEC requirements Article 555 Marinas & Boatyards, which rolled out in 2011, requires a 100mA ground fault protection level for marina dock feeds. In the upcoming 2017 NFPA 70 / NEC 555 this maximum level has now dropped from 100mA to 30mA. You are trying to plug your vessel into a 5mA trip level GFCI.

(Copy & paste of a previous reply)
The Problem With the New Mandates:

#1
NFPA 70 / NEC requirements do not mandate 100mA or 30mA protection at each dock pedestal, which would be the only prudent way to adopt or phase this into an entire industry where the safety standards are voluntary and arguably grossly ignored.

As I type this I am currently waiting for a customers phone to cool down so we can continue troubleshooting his shore system via video messaging. He is in the BVI and can't find a decent electrician to save his life. So far we've found on-board AC neutral bonded to AC Earth and his two 30A shore inlets have common neutral bonding. Somewhere in his travels he had a failed 8kW generator ripped out, by some hacks, who left a ghost transfer switch and ran the ghost wires to where ever they found an open terminal. It is a freaking mess, a mess I repeatedly tried to talk him into fixing before he headed off cruising, "seems to work" he'd say.... He began complaining of issues when his vessel began tripping up to code marina's and shutting entire docks down. The non-transients at these marinas were none too happy and the marinas finally told him not to plug in..

As a result of NFPA/NEC not requiring 100mA or 30mA ground fault protection at the pedestal level, for each boat, any vessel plugging into a dock pedestal that is protected by an upstream ground fault device can create nuisance trips for every boat on that same feed. This = BAD (safe, but bad)

Shore based ground fault devices that cover multiple pedestals (boats), can result in a nuisance trip that depowers all the boats on that string and create a lost power situation to all of those vessels, just as my customer has done, at no less than 3 or 4 marinas since leaving Maine.

This NFPA / NEC roll out has already cost boaters significant $$ in destroyed battery banks etc.. Unfortunately the boaters who lost out may not have been the ones who created the problem just the recipient of what I often refer to as Darryl & Darryl wiring, for those old enough to get the Newhart reference.. No offense to any Darryl's out there....

The new NFPA / NEC ground fault requirements for marinas is only serving to expose the horrendous wiring that has gone on in the marine industry for far too long. Even if your boat is properly wired, to ABYC standards, you can still suffer the consequences of Darryl & Darryl hack jobbing their own boat wiring because the NFPA/NEC requirement is not at the power pedestal/individual boat level.

For what it is worth I have very infrequently come across an owner who believed it was their boat creating the leakage or corrosion issues. In almost all cases it starts out as "someone else's problem" until the fault is found on-board...

#2 Far too many boats out there are not wired to meet or exceed the ABYC safety standards. The NFPA / NEC could really care less about this, it's not their issue. When you plug an incorrectly wired vessel into the new NFPA /NEC shore standards, requiring ground fault protection, it can now become everyone's issue not just the problem vessel. Incorrectly wired vessels create problems for everyone at an up-to-code marina.

Boats that are not wired to current ABYC standards, as a group, have very, very high ground fault percentages. For example the number of boats I measure with AC grounding (GREEN) and AC Neutral (WHITE) bonded on-board the vessel (A huge no-no) is in the range of 35-40% +/-. This is INSANE, but it is the reality of a voluntary standard that has gone largely ignored by boat owners, or DIY wiring done by local dock-experts who think they know more than the standards organizations, and far too many folks who call themselves marine electricians..

Bottom Line? Improperly wired vessels, vessels not wired to ABYC standards, can cause nuisance tripping of shore ground fault interrupters. This issue will be rarer at 100mA or 30mA and quite a common occurrence at 5mA...

The sheer age of many vessels also means some of them have equipment that is so antiquated that it too creates an inadvertent neutral to grounding bond on-board the vessel. Improperly wired inverters, generators, transfer switches, automotive grade battery chargers, auto grade inverters, improperly wired hot water heaters etc. are all hot button areas where a neutral/grounding bond may be hiding. Some boat owners & terrestrial based electricians have also been known to place a jumper between neutral and grounding bus.

#3 The Rx?

Marina Rx:
Marina's who want happy customers should ideally install a 100mA or 30mA ground fault device at each pedestal, not 5mA. The GF device (GF=Ground Fault) should be installed at each pedestal so one boat or transient can not take out an entire dock or entire group of vessels due to dangerous wiring practices. Adding a GF device at each pedestal is in compliance with NFPA 70 / NEC and actually exceeds the minimum requirements.

By installing a ground fault device at each pedestal, this prevents Darryl & Darryl's stellar wiring job from taking out your boat when they create a nuisance trip. These ground fault devices should not be daisy chained to the load side of the GFI and should serve only that pedestal.

Marina's also need to comprehend and understand that GF leakage is additive. If we have ten boats each leaking 4 mA, which is not even enough for each boat to trip an individual 120V 5mA GFCI, those ten boats together can trip a single 30 mA ground fault device.

Marina's should prohibit vessels that cause a nuisance trips, from plugging into their system, until the fault has been corrected. If a vessel is tripping a 100mA threshold device (and this is not due to additive leakage) this creates a very dangerous potential for electric shock drowning.

The issue & mess of nuisance tripping will only get worse now that the NEC has dropepd to 30mA. Why? Because the drop in mA trip leakage does not technically require protection at the individual dock pedestal level. Frustrating to say the least.

Marina's need to fully understand the new requirements and be trained on how to conduct spot audits and to check for individual vessel issues that would otherwise create problems for the rest of their customers. Or do it right and install a 30mA device at each pedestal, this way only the miswired customer is left without power..

When a marina is re-wired, or the wiring touched by a professional, they now need to become in compliance with the current shore based standards. The mandatory shore based NEC/NFPA standards extend to the dock pedestal receptacle, and the voluntary ABYC standards begin at the shore power cord set.

This problem of nuisance tripping is only going to get worse, much worse as time goes on and more and more marinas become in compliance with the NFPA 70 / NEC requirements. Once the code drops to 30mA, to protect multiple pedestals, it will become a complete debacle..



Boat Owner Rx: Wire your vessel to the current ABYC standards and you will no longer create dangerous situations, power loss or dead batteries for those around you who do have properly wired boats.

Two Easy Tests for 120V 30A Service (these two tests barely scratch the surface but it's a start):

1-
Use a high resolution AC clamp meter set to measure A or mA. Extech, Yokogowa and Fluke all make excellent AC leakage clamp testers. Ideally every marina should own one. Power up your on-board AC devices (hopefully all of them) & place the clamp around your shore power cord. The reading should be 0.0A. Any reading above this is indicating an amperage imbalance between the hot and neutral AC conductors and indicating that this missing current is leaking elsewhere eg: into the water..

2- One of the easiest tests or starting points is to physically unplug your vessel from the pedestal and be sure your inverter is decoupled from DC so it does not auto-invert. Make sure any manual transfer switches are set to SHORE. Now test for continuity between AC WHITE/Neutral and AC GREEN/Earth/Grounding pins at the shore end of the cord or at your on-board grounding bus and neutral bus.. There should be no continuity.

If you find issues you are unsure of I would suggest bringing in a professional....
Don’t worry, I know when I’m electrically challenged and will get professional help.