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 ground
ing (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....