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Old 02-15-2017, 12:15 PM   #41
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How do you test for a ground capable of carrying significant current, so you know the ground is a ground that can handle the fault?
You have a really good point. One strand of one wire if clean will show as a nice low resistance when using an ohmmeter. Of course in a shorted hot wire situation, it probably wouldn't provide protection.

I have a tester right here just for the purpose of verifying a very solid ground exists in an AC power cicuit. (Not cheap - a couple of boat bucks or more) It uses two cables, one is heavy wire with a large clip that is clipped to a chassis or other known ground. Then an AC type cable is plugged from the tester to the unit to be tested (in reality, only the ground wire is used). In the case of a boat, it would be from the tester to the shore power input. When the test is started, the tester momentarily puts about 35amps through the ground wire in the AC cord and it comes back out the heavy cable that has been clamped to the known ground. While this is happening, the tester is able to measure the resistance of the ground wiring involved during this heavy load. If it is under a certain number - you know the ground is very good.

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Old 02-15-2017, 02:18 PM   #42
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.................... ....................... But I have yet to plug in any place where the electrician has reversed the polarity.
You should know that not every marina calls in a proper electrician to replace receptacles and such. Often the person sent to do the job is nothing more than a dockhand with no electrical experience. That's one reason we have reverse polarity indicators on our boats.

As far as testing a (marina's) ground circuit's capacity, I suppose you could connect a load from hot to ground but if there is a problem, you could be screwing up a bunch of boats. It's probably best to just use a plug in tester or your boat's reverse polarity circuit if it has one as in my post above.
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Old 02-15-2017, 03:27 PM   #43
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The correct tool to use is a groundloop impedance tester, along with a megger for any insulation leakage. Both very expensive tools not carried by your average electrical contractor. On the few jobs where I needed to certify resistance numbers, it was easier to hire an engineering firm that specializes in this.
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Old 02-15-2017, 04:37 PM   #44
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Sales of isolation transformers is going to increase.
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Old 02-15-2017, 05:04 PM   #45
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Sales of isolation transformers is going to increase.
Absolutely. Particularly for older boats with years of salt air inside that causes many minor ground faults. I would add an isolation transformer to my old boat, before I would try to chase down minor faults.

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Old 02-15-2017, 05:10 PM   #46
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Absolutely. Particularly for older boats with years of salt air inside that causes many minor ground faults. I would add an isolation transformer to my old boat, before I would try to chase down minor faults.

David
Most salt air induced faults are going to be at wire terminations to devices. In my boat, i have easy access to everything, nothing is buried too deep to get at. I have 8 branch circuits. Outlet runs to areas that could get wet I made to be unpluggable, which means I can open a door, and unplug the line from an outlet.
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Old 02-15-2017, 05:32 PM   #47
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In old boats problem come mostly time from refrigerator with common ground. Ground and neutral are attached together so trip the very sensible brand new wire system. Check around, it's tricky sometimes.
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Old 02-15-2017, 06:02 PM   #48
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Absolutely. Particularly for older boats with years of salt air inside that causes many minor ground faults. I would add an isolation transformer to my old boat, before I would try to chase down minor faults.

David
Considering the price of an isolation transformer up here I would first try to find the ground fault
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Old 02-16-2017, 07:26 AM   #49
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The current NFPA 70 / NEC requirements Article 555 Marinas & Boatyards, which rolled out in 2011, requires a 100mA ground fault protection level for marina docks. In the upcoming 2017 NFPA 70 / NEC 555 this maximum level is reportedly going to drop from 100mA to 30mA.

The Problem:

#1 NFPA 70 / NEC requirements do not 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 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. 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.

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 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.

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 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 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 The Rx?

Marina 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 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. The issue of nuisance tripping will only get worse when NEC drops to 30mA in 2017..

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. Once the code drops 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.

Two Easy Tests for 120V 30A Service:

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....
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Old 02-16-2017, 08:01 AM   #50
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While an isolation transformer will eliminate nuisance tripping of marina GFCI breakers, it doesn't solve the problem of potentially dangerous wiring on your boat. It's a cover up.


Someone mentioned refrigerators with the neutral and ground wired together. I've never seen this and it's against code on a boat or on land. Maybe it's just an Internet old wives tale. There should be no connection between the neutral and ground conductors on your boat except when the inverter or genset are running.


Turn off any inverter or genset, unplug your shorepower cord and check for continuity between the ground and neutral pin. There should be none. Check between the hot and ground pin. Except for the reverse polarity circuit I mentioned above, there should be none.


If you see any continuity, either find where it is and fix it (if this is within your capability) or hire a marine electrician to fix it.


If your reverse polarity circuit is causing a problem with a marina GFCI, you will have to disconnect or modify it. You can just use one of the $10 plug in polarity checkers from the home center instead.
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Old 02-16-2017, 08:36 AM   #51
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Wes:

Individual circuit breakers are available for your home's electrical box with built in GFCI protection. Almost all marina power pedestals have breakers protecting the 30A and two pole 50A receptacles. Are there similar breakers available that could replace these and easily provide protection to the individual pedestals?

And I agree that an isolation transformer is a partial fix. But I have been on boats where the only way to fix their ground faults would be a total rewire job. Lot's of Darryl and Darryl, well Charles in this case.

David
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Old 02-16-2017, 08:45 AM   #52
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Wes:

Individual circuit breakers are available for your home's electrical box with built in GFCI protection. Almost all marina power pedestals have breakers protecting the 30A and two pole 50A receptacles. Are there similar breakers available that could replace these and easily provide protection to the individual pedestals?
I don't know the answer to that but my bet would be that these are available.

A system where on boat with a ground fault kills power to an entire dock is totally unacceptable. You don't want your refrigerator or battery charger turned off every time a new boat plugs in.

Only an idiot would design and install something like that.
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Old 04-09-2017, 08:52 PM   #53
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It happened again today at Fort Pierce City Marina on their new floating docks. Only the single power pedestal blew each time we switched on our power instead of the entire dock. The Dock master said it was happening all the time. We moved to an older slip and all is well.

If the electrician knows I would think that dock master should know too if this happens all the time. I don't mind paying to fix it if someone knows what is wrong with my boat.
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Old 04-09-2017, 08:58 PM   #54
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It happened again today at Fort Pierce City Marina on their new floating docks. Only the single power pedestal blew each time we switched on our power instead of the entire dock. The Dock master said it was happening all the time. We moved to an older slip and all is well.

If the electrician knows I would think that dock master should know too if this happens all the time. I don't mind paying to fix it if someone knows what is wrong with my boat.
If you can't find what it is, then get a marine electrician to check out your boat.
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Old 04-09-2017, 09:08 PM   #55
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If you can't find what it is, then get a marine electrician to check out your boat.
As I said above, I would be happy to do this if he knows what causes the problem and can fix it.
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Old 04-09-2017, 09:15 PM   #56
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Another way would be to take a short shore power extension cord, and cut back the jacket so you have good access to the wires inside the cable jacket. Then check with a quality clamp on ammeter.

For 120V 30A, clamp the line and neutral wires together. The meter should read zero. Then clamp the ground wire. It should again read zero.

For 240/120V 50A, clamp L1, L2, and neutral together. It should read zero. Clamp the ground wire. It should read zero.

If you measure current on the ground then power is coming back through your boat's ground.

If you measure current (actually a current difference) in the power lines, but nothing in the ground, then you have power leaking out through your hull fittings and back to ground through some water path.

As I think about it, this is probably the better test because it gives more insight into what's wrong, and the magnitude of the problem. It would also show small leakage that's too little to trip a breaker, but might be the last straw at a marina of other leaky boats.
Hmm so if you have a 240V load across the legs, phase will zero out the meter? Had never thought about or tried this... just seems counterintuitive because unlike neutral wire in a dual leg load there actually *is* net current flowing
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Old 04-09-2017, 09:28 PM   #57
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As I said above, I would be happy to do this if he knows what causes the problem and can fix it.
A good marine electrician will know.
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Old 04-10-2017, 09:46 PM   #58
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I had a good marine electrician out of Vero Beach on the boat today for almost four hours and he discovered a number of issues.

He stated that he had worked on about 40 boats in this marina for the problem since the rewire.

First he gave me an explanation for dummies of the new code in regards to current going to unintended places and why this will trip a new code breaker. In dummy terms (I refuse to believe in electricity at all. I just know it is there at the wall plug when I need it). For instance, let's say a boat receives 5 amps from the dock...it should return 5 amps to the dock. If it returns less then the difference has gone elsewhere. Perhaps to somewhere else on the boat and possibly found its way to the water around the boat. If the difference is over 30 milamp the breaker will trip.

What he found on my boat was that a few of the systems that were wired to always flow current through the inverter shared a connection with some systems that were not run by the inverter. He sorted these out. He also found that the refrigerator and icemaker and were wired incorrectly and he fixed these. Icemakers are a common cause of this problem...he said.

We are now sitting on the newly wired dock getting power.
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Old 04-10-2017, 10:45 PM   #59
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We are now sitting on the newly wired dock getting power.
So glad you got someone out to do that. Not only fewer issues for you, but your boat is safer today than yesterday. Maybe only a few percent safer, but when it comes to fires, I don't like gambling on the percentages.
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Old 04-11-2017, 06:01 AM   #60
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" If the ground and neutral are bonded on the boat, I expect it would be in or around the main electrical panel. It could also be at the generator, and not being disconnected when on shore vs gen power. Or inverters are another possible location."

The installed or a temporary battery charger might also trigger the fault.
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