Galvanic isolator and ELCI precedence

Discussion in 'Electrical Systems' started by geste, May 14, 2011.

  1. geste
    Joined: May 2011
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    geste Junior Member

    All,

    On my last boat I finally got my brain wrapped around galvanic isolators. I added one, and for what it is worth, my zincs started lasting a lot longer.

    Now ABYC standards call for ELCI on AC inlets. Some of what I have seen says ELCI should be the first thing in line after an AC shore power inlet.

    Am I right in thinking that galvanic isolator would still come first and then ELCI?

    My local shop is selling galvanic isolators made by "Dairlyland". I went "Huh?", but it is an outfit in Wisconsin and the unit looks fine -- Dairyland Electronic Industries.

    Jim
     
  2. Dean Smith

    Dean Smith Previous Member

    I put transformer(PROTECTION galv action) first and elci second and boy are they good, I have in my house too and they work, they also save some dumbos from destroying equipement by not finding why the the breaker or fuse goes
     
  3. Mark Cat
    Joined: Jun 2011
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    Mark Cat Senior Member

    The ELCI for new boats will replace the shore power beakers. Basically a 30mA multipole GFCI breaker or RCD.

    For boats without an isolation or polarization transformer, a polarization detection device will be needed on the shore power side of the ELCI or AC breaker protection will require multipole breakers to also open the grounded conductor (neutral). See ABYC E-11.

    The shore power procedure goes like this:

    1) Turn off the ELCI.
    2) Connect the shore power cable to the boat.
    3) Connect the shore power cable to the pedestal.
    4) Check for proper polarity on board the boat.
    5) If OK, turn on the ELCI.
    6) If not OK, disconnect and inform the dock master.

    Mark
     
  4. Ike
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    Ike Senior Member

    Starting from the shore side the ELCI is first, then the galvanic isolator.
     
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  5. Mark Cat
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    Mark Cat Senior Member

    The galvanic isolation (use one with failsafe) is placed in series with the grounding green wire. The ELCI compares the Ungrounded (Black) and Grounded (White) current flow for 125VAC installations.

    So the two devices are usually within 10 feet of the shore power boat inlet.

    Mark
     
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  6. klims106
    Joined: Jul 2011
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    klims106 Junior Member

    Ike,
    I hope you are still listening to this thread. I did start a similar thread yesterday on the same matter.
    Your statment "ELCI is first, then the galvanic isolator" does reflect what ABYC requires. But I believe like dean that this is not serving much and that ELCI should be on the secondary side of the transformer. Since the secondary is grounded a ground fault current will go back to the isolation transformer and the primary side current will be perfctly balanced. The only thing protected by the primary side is the transformer itself. Now if ABYC's requirement was to install the ELCI at the shore power outlet like ISO requires, you would also provide a level of protection from leakage current from the boat or the shore power cord through the water thus reduce the risk of in water electrocution. But as it stand I fail to understand ABYC's logic.
    Am I missing something?
     
  7. Ike
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    Ike Senior Member

    I'm listening

    Well, since I was not in that meeting and only read the minutes I can't say what the nature of the discussion was. But I have read a lot of info on it and here is the gist of it. The idea is to detect any leakage current from the whole electrical circuit on the boat. To me that would include the primary of the transformer and the shore power cord. It doesn't seem to be reasonable to measure only the current off the secondary. You want to know if the current in the primary is leaking as well. If you only measure the current in the secondary you leave the primary and the shore power cord uncovered. In Europe they do this with an RCD at the power outlet on the dock, but here ABYC has no jurisdiction (so to speak) over the circuits on the dock, only on the boat. Circuits on the dock are covered by the National Fire Protection Association (NFPA). So whatever ABYC does has to be on the boat, but the only way to cover the current in the primary and the shore power cord is to put the ELCI in the primary.

    Don't know if my explanation makes sense or not . But that's how I see it.
     
  8. sdowney717
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    sdowney717 Senior Member

    GFCI breaker protects only downstream current from itself.

    ELCI is this not the same? Input wire not protected, downstream from ELCI breaker wire is protected?

    If so then having ELCI on the boat as the main breaker does nothing with the shore power cable.

    ELCI breaker needs to be in the shore power pedestal. Why not?

    Why not likely because no one wants to pass a law to force marina owners to spend the money and then raise slip fees.

    Our old marina we have standard 15 amp plugs to attach power cords.
    Our power is unmetered so it is free.

    What is acceptable losses from electroshock on the water involving boats. I have been boating and at marinas for several decades and have no personal knowledge of deaths.
     
  9. Mark Cat
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    Mark Cat Senior Member

    In production designs where there is liability:

    The shore power approach should address all of the failure modes at the pedestal even if an ISO RCD is used. Never tested? Corroded? Poor maintenance?

    The boat shore power equipment and procedures are designed so the boat is safe, no matter how the shore power is (mis)provided, ISO, ANSI, UK or US.

    All for now,

    Mark Cat
     
  10. jonr
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    jonr Senior Member

    > Our old marina we have standard 15 amp plugs to attach power cords.

    Luckily you can buy portable plug GFCIs that will plug in there.
     

  11. sdowney717
    Joined: Nov 2010
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    sdowney717 Senior Member

    I have one of those, I do not use it. Use the std yellow cord. I also have 2 gfci circuits coming from my breaker panel feeding the outlets and the microwave. I specifically left my AC fridge non gfci as I never want to see a nuisance trip on that. I suppose the cruisair heat pump could have a gfci. Only other circuits are 2 resistance cabin heaters, water heater, princess oven. I could likely convert all breakers to gfci. I have read the nuisance tripping which I never experience is why people do not do that.

    Does GE make ELCI dual pole breakers that would fit in a standard GE box?
    I would actually consider buying two if the price was reasonable.
     
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