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Old 08-09-2013, 17:30   #1
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Join Date: Jul 2011
Location: Maryland, Right Now
Boat: Morgan 452
Posts: 143

I am going through a major refit and I just got the boat back in the water. The boat is a 1978 Morgan ketch with some significant PO "upgrades." I think I have removed most of the upgrades, but there is still a significant amount of original A/C wiring.

Before starting the refit, I had a survey done. Two of the things that the surveyor suggested were the addition of ELCI breakers on the shorepower inlets and the addition of either an isolation transformer or a galvanic isolator. Also as part of the upgrade, I added a NextGen 50 amp A/C generator.

I have two shore power connections. One feeds the house loads, which consist of a Mastervolt battery charger, a water heater, a Mermaid HVAC unit and a Xantrex inverter. The inverter powers all of the boat's sockets, but no other loads. The other connection only feeds a Cruisair reverse cycle HVAC.

In the old system, each shorepower line went to a dedicated 30 amp breaker, then to individual breakers. Because I added the generator, I added a Blue Sea three position selector switch (Shore-Off-Generator). From the selector switch, I now have two 30 amp ELCI breakers. These replaced the dedicated 30 amp breakers in each shorepower line, although they can now be fed by the two shorepower lines, or the generator.

In addition, I added a Zinc Saver 60 with a separate monitor unit. The ground lines for the two shore power connections route to one side of the Zinc Saver, then the ground lines split out again and run to a single point buss. All ground lines, including the generator, attach to this bus, so they should all be at nominally the same potential.

The monitor unit for the GI has two lines for each of the two shore power connections - one hot and one neutral. I believe that these are all hooked up correctly.

The neutral lines for each ELCI run together to a single neutral buss, to which the neutral lines for all appliances are connected. This ties the neutral for the Cruisair HVAC unit to the neutrals for all of the other house loads.

I am in a slip with a single 50 amp breaker and connector. From that connector, i have a Marinco 50 amp to dual 30 amp connectors. I then have the two 50 foot 30 amp shore power lines.

I have finally gotten all of this installed and, to the best of my knowledge, hooked up correctly. However, both of the ELCI breakers trip open immediately, when I try to shut them.

I believe the Galvanic Isolater is working correctly. It has a 3 light readout for reverse polarity, ground wire and isolator and all three lights are green.

I have not tried to use the generator yet. I want to make sure that the rest of the system is working before adding that wrinkle. One of the issues with the generator is that the ground and the neutral come off the same lug, so that they are interconnected.

I have read what I can about ELCI breakers, but I haven't found anything that mirrors this particular set up. I have read that the neutral and the ground connections on the ELCI load side sould not be connected together, but I haven't seen anything about them being connected upstream of the ELCIs, as is the case with my generator. I also understand that some chargers and inverters do something similar, tieing the chassis ground to the negative bus on the DC side, which is also connected to the A/C ground system in some cases.

My immediate thought is that, because I am running the neutral for the Cruisair HVAC to the same buss as all of the other loads, the two ELCIs are "seeing" that connection as a fault. However, I am getting this trip before I close any down stream breaker, so I don't see how that could be the issue. I have considered the possibility that the breakers are both bad, but the probability of both breakers being delivered faulty seems very low.

My next trouble shooting test will be to disconnect the load side lines for each ELCI breaker and see if this allows the breakers to close. I believe that this would simulate a "perfect condition" all breakers open situation. But before I start tearing everything else up, searching for some phantom ground, can anyone with experience see if I am doing something just terminally boneheaded?

I read one place where some suggested that the ELCIs should be upstream of the galvanic isolator, but since the ELCIs only monitor the neutral (white) and hot (black) lines and the galvanic isolator is monitoring the green line, it doesn't seem like this should be the case. Although, of course, the galvanic isolator monitor is hooked up to the white and the black lines for each shorepower connection. Perhaps those connections should be on the load side of the ELCIs instead of the line side?

Thanks for any help. If removing the load output from the ELCIs doesn't clear the problem, I will replace them with standard 30 amp breakers, but I really don't want to start swapping out equipment until I have ruled out everything else.
CaptFrankM is offline   Reply With Quote

galvanic isolator

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