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Old 11-03-2019, 07:08 PM   #21
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I was lucky and found a bond between the neutral and safety bus bars two years ago. I was specifically looking for it because of what I read here about the "new" ELCI-equipped pedastals. I had not yet had a problem up till then but it was obvious from those early discussions that many boats might. Mine would have. In my opinion, any boat that is tripping an ELCI pedastal needs to look first for a bond between the neutral and safery bus bars before looking for other causes.
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Old 11-03-2019, 07:13 PM   #22
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What I have seen with boats from the 80s with 2 shore power inlets is that they put all the neutrals on one bus bar. It worked then but it won’t work now with the newly wired docks.
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Old 11-03-2019, 07:23 PM   #23
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What I have seen with boats from the 80s with 2 shore power inlets is that they put all the neutrals on one bus bar. It worked then but it wonít work now with the newly wired docks.

Interesting... I should check for that on mine. I've never hooked up to 2x 30A with GFCI, only a 50A 125/250 split to my 2x 50A 125V inlets. So the neutrals get combined before the GFCI anyway in that case, hence the lack of trips.
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Old 11-03-2019, 08:04 PM   #24
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Yes, a Y connector will hide the combined neutrals.
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Old 11-03-2019, 10:23 PM   #25
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Again, it bears repeating once more, incorrect Ground to Neutral connection onboard causes fault current that trips GFCI/ELCI. As well, it is an adverse influence on corrosion and should be checked for that reason alone. G-N connection is only at a prime source of power (Generator, Transformer or Inverter) and only connected into the ship's buss when that source is providing power. (exceptions, but I don't want to digress, seldom on pleasure boats)

Keep in mind that actual ground faults cause fault currents too, that's why the GFCIs are being required. The current observed from the G-N fault is a portion of the boat's Neutral buss load, which then has a parallel path with the Neutral conductor back to the source, a G-N connection at the distribution panel or transformer serving the receptacle. Note, the fault current varies in proportion to the Neutral current, so it varies with the ship's load and load balance between legs in a 120/240V system. This is important to know if you're switching off circuits looking for one that is the cause. If you're seeing an actual live wire insulation fault it will go away all at once when de energized. If it changes with multiple circuits on the boat, its a GN fault.

A galvanic isolator will not influence the GFCI. Monitored models do apply DC voltage to the ground, but the GFCI is sensitive to AC only, besides the current would be very low. A galvanic isolator is redundant if an isolation transformer is installed and wired correctly.

Inverter installations must not have the Output Neutral connected to the Ship's Neutral buss. Transformer installations must not have incoming Ground connected to ship's Ground. Installations of 240V domestic appliances that use a Neutral wire must include 4-wire cords and receptacle wiring - many are sold with 3 wire cords and have a G-N jumper in the connection box. Things that can cause this issue may have been in place for a long time without any observed problems. As often as I've found any of the above, I have also found a jumper between the ship's Ground and Neutral busses. I've found the above problems the cause of fault currents far more often than live wire faults.

The last one of these I dealt with was 3 days ago. There was no observed problem, it was a survey item, fault current measured on the shore Ground. Below, the Ground connections of a transformer installed on a very high end yacht by a supposedly reputable outfit. You see all three grounds on the case stud, and 330 Ma on the meter. The incoming ground wire from the dock gets connected to the transformer shield, the two small ones, and that connection isolated from the case and ship's Ground. Note that the Neutral and Ground are not connected. This is one of those exceptions noted. The boat is equipped with Ground Fault monitoring and one N-G connection for all sources is at the switchboard through a sensing device. This is common on inspected vessels.
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Old 11-03-2019, 10:37 PM   #26
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Inverter installations must not have the Output Neutral connected to the Ship's Neutral buss.
Can you expand on how a circuit is completed for items that have neutral connected to shore buss bar.
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Old 11-04-2019, 01:49 AM   #27
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SooValley,

Practice in years past, for right or wrong, was to have a single neutral bus. Both inverted and non inverted loads were connected to it.

When not inverting, everything worked as normal. In effect, the inverter wasn't part of the circuit. When inverting, the inverter acted as a source and tied neutral to ground.

The challenge now is that inverters start up with relay closed until shore power ioens it. During that time, neutral and ground are tied.

So, to directly answer your question, the hot wire supplies power to the load which completes the circuit via the neutral wire to the relay and then, via the relay, through both the neutral and grounding conductor wires to the source on shore at which point both the grounding and neutral conductors are tied together.

When the neutral and ground are ties together, current returns via both. The current returning via the grounding conductor pops the GLCI and/or ELCI.
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Old 11-04-2019, 08:21 AM   #28
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We found 4 problems that would trip the GFCI. His neutrals were all on one bus bar. His 2 voltmeters were daisy chained with the neutrals from one shore power. One of his outlets had been replaced by a PO and they swapped the neutral and ground on the outlet. And his water heater had a ground to neutral short....
Glad you survived that visit! In the equipment I design, we have a 2000 Volt isolation spec to meet from L and N to G. I would submit the water world needs the same. Even so, the 2kV will only catch gross clearance failures and inadvertent shorts.
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Old 11-04-2019, 09:42 AM   #29
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I explained what would happen if someone was in the water with the ground and neutral swapped on the outlet, ESD. He said that he had been in the water between the boat and shore and his muscles locked up. He thought it was due to the water being a bit cold. Fortunately he was only standing on the bottom and was able to get to shore. If he had been in deeper water he may not have made it.
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Old 11-04-2019, 10:41 AM   #30
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...

The last one of these I dealt with was 3 days ago. There was no observed problem, it was a survey item, fault current measured on the shore Ground. Below, the Ground connections of a transformer installed on a very high end yacht by a supposedly reputable outfit. You see all three grounds on the case stud, and 330 Ma on the meter. The incoming ground wire from the dock gets connected to the transformer shield, the two small ones, and that connection isolated from the case and ship's Ground. Note that the Neutral and Ground are not connected. This is one of those exceptions noted. The boat is equipped with Ground Fault monitoring and one N-G connection for all sources is at the switchboard through a sensing device. This is common on inspected vessels.
Run this by us again. There is a IT, and the wiring was OK? N and G are separated, as is the dock earth from ships earth. What was causing a 0.3A shore earth current?? That would have had to be leakage from shore power inlet wiring to the IT?

Basically, the only item(s) on board connected the shore earth are the metal inlet socket, correct?

ps; for clarity, this design used GFCI to trip in case there is a primary to earth IT fault. On the secondary winding side, N bonded to E/G, right?
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Old 11-04-2019, 10:49 AM   #31
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Thanks I have found the answer I was looking for. The inverter switches both hot a d neutral. Shore power passes through inverter. inverter alone supplies both a d bonds to ground without shore power. Brain fart solved
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Old 11-04-2019, 11:42 AM   #32
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Diver Dave,

I'm not following either. Assuming, which is a funny approach, that the vessel is wired correctly and has ELCI properly installed and assuming that the onboard ELCI isnt tripping but the shore GFCI is tripping, I'd have to hazard a wild guess of salt water or some other leak at the shore power inlet or power pedestal, at or near the fixture interface, e.g. cord, recepticle, associated wiring.

But, I just didn't follow :-(
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Old 11-04-2019, 12:51 PM   #33
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For Diver Dave & others
Below is a pic of the corrected connections, sorry the angle isn't good. The ground wire from the dock is connected to the IT shield, and the wire to the ship's ground - which is bonded to the neutral at the switchboard, is connected to the transformer case. There is no continuity between the incoming ground and ship's ground buss. In the previous pic all these are connected together, establishing a parallel circuit between GN connections in two places, the boat's switchboard and the dock distribution panel. There is no GFCI on the dock in this case. If there was it would have tripped because a portion of the load current is bypassing the device and unaccounted for. That's what the GFCI is sensing - any unaccounted current means power is going where its not supposed to go.

If a metallic inlet is used, it must be bonded to the incoming ground wire and isolated from the ship's ground buss. Otherwise the parallel circuit will be established. This installation is 100A and uses non metallic pin-and-sleeve connectors. The installation has a GF monitor on the secondary side which activates an alarm.

When installing an inverter, first identify all the neutral wires of the circuits that are to be inverter powered. This is usually most easily done by turning each circuit on, make sure there is some kind of load on each circuit, and measure the current on the hot wire with a clamp-on ammeter at the circuit breaker, then find the neutral wire on the buss with the same current. Install a new buss and connect all these to it, and wire the new buss to the inverter's N output. Connect the inverter N input to the existing N buss. When I say the inverter output N is not to be connected to the ship's N, I mean no external connection. The inverter will make the appropriate connections internally.

Hopefully these points are helpful. It's not practical to cover every detail that might arise and have a concise and readable post.

"This post is not intended to contain the complete solution to any particular issue"
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Old 11-04-2019, 01:10 PM   #34
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I might have missed it because I'm cruising right now and only skim the previous posts, but old style reverse polarity lights if they didn't have enough resistance sometimes will trip these new dock. based gfi's
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Old 11-04-2019, 03:44 PM   #35
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Today, I unplugged by galvanic display and that solved my issue for now....not a fix just a solution until Iím back to my dock.. thanks everyone
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Old 11-04-2019, 04:56 PM   #36
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Today, I unplugged by galvanic display and that solved my issue for now....not a fix just a solution until Iím back to my dock.. thanks everyone
That's what I did too. And I bought a Hubbell tester for the shore power pedestal to make sure the power there has no problems.
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Old 11-04-2019, 10:48 PM   #37
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There's an error in my last post, somebody can spot it before I reveal...?
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Old 11-05-2019, 09:06 AM   #38
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There's an error in my last post, somebody can spot it before I reveal...?
When I say the inverter output N is not to be connected to the ship's N, I mean no external connection. The inverter will make the appropriate connections internally.

Did U mean G instead of N? My reading comprehension is no where near as good as my schematic reading ability.
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Old 11-05-2019, 11:17 PM   #39
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There is no GFCI on the dock in this case. If there was it would have tripped because a portion of the load current is bypassing the device and unaccounted for.
With an isolation transformer installed, the current would not go back to the dock, a dockside GFI would not trip. But now, there is a mystery since I sketched it out. I'm not quizzing, I don't know the answer. The current was there on the ship's side ground wire, gone with the connections changed, but where did it originate from? Five drawings here, only the essential elements with paths of load and fault current. Currents flowing through the water from elsewhere aren't being considered. 1 is the transformer connections as found; 2 is as changed; 3 is the same but as would be found on most pleasure boats; 4 shows the path of load current when there are two G-N connections - the crux of the subject I'm on here. 5 is with no transformer installed onboard.

The boat does have a Ground Fault detector and alarm, but it hadn't been working since(?) because the 24V fuse supplying it was blown.

I'm off to different parts soon and won't be back to this boat till spring, it will get some further investigation then.
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Old 11-08-2019, 01:56 PM   #40
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Itís highly unlikely to be the galvanic isolator. You should contact a yard or marine electrician and have an ELCI master breaker installed. This breaker preforms the same function as the docks GFI. Once the ELCI breaker is installed you will know that your boat is not the issue.

In your case it might be as simple as a ground neutral bond but I have also see appliances that have internal failures cause this issue.
What he said. Unless you are a marine electrician, I would hire one. Hunt and peck for the source of the problem is a risky way to go. I have heard (and believe) that most boat fires are electrical in origin.
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