Originally Posted by ranger42c
IIRC, one posit of that long thread was that if "your boat" trips the new GFCIs, there really is something wrong and it needs fixing... no matter whether "your boat" doesn't seem to have that problem at other older-style dock systems.
The only possible reason this may not be 100% true is for "cumulative" leakage where your boat may be leaking only 4mA but the other boats on the 30mA GF circuit are leaking a sum of 26mA. Your boat may be the one to push it over the top.
That said your boat should not be leaking anything, and if wired properly, would not be. You could write an entire book on this subject but still the average owner can do a few things to test for these issues.
As marinas update dock wiring they need to become in compliance with the new codes. Many marinas are pushing this off as long as they can to avoid the expense.
The current NFPA 70 / NEC requirements Article 555 Marinas & Boatyards
, which rolled out in 2011, required a 100mA ground fault protection level for marina docks. In the 2017 NFPA 70 / NEC 555 this maximum level was dropped from 100mA to 30mA. What is so frustrating about the updated land based marina standards, is that it does not require GF interruption for each pedestal
NFPA 70 / NEC requirements do not specifically mandate 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 the voluntary standards are arguably grossly ignored
As a result of not installing 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 circuit. Shore based ground fault devices, that cover multiple pedestals (boats), can result in a trip that depowers all the boats on that string and create a lost power situation to all of those vessels.
The 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 actually caused /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 NFPA / NEC ground fault requirements are 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. The only way to get around this major issue is for a marina to install GF protection at each pedestal so that only the offending boat loses power..
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. Even when you can show them the problem, with physical measurements, they are still often in denial.
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 becomes everyone's issue not just the problem vessel.
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 is in the range of 35-40% +/-. This is absolutely insane
Bottom Line? Improperly wired vessels, vessels not wired to ABYC standards, can cause nuisance tripping of shore ground fault interrupters.
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.
#3 What's the Rx?
Marina's who want happy customers should ideally install a ground fault device at each pedestal so one boat can not take out an entire dock or entire group of vessels. This 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.
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 110V 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. If we thought this issue was bad at 100mA, the issue of nuisance trips is only going to get worse now that the NEC has dropped to 30mA.
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 offending customer is left without power.
When a marina is re-wired they now need to become in compliance with the current shore based standards. Shore standards extend to the dock pedestal receptacle and ABYC standards begin at the shore power cordset.
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. Now that the code has dropped to 30mA, to protect multiple pedestals, it will become even worse.
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. Also if you have a self testing galvanic isolator
get rid of it and replace it with a Fail Safe Galvanic Isolator. The automatic testing GI devices will trip a GFCI. There are many more tests than below but these two are pretty simple as a baseline..
Two Easy Tests for 120V 30A Service:
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..
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.