Announcement

Collapse
No announcement yet.

Galvanic Isolator Wiring on 3870

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Galvanic Isolator Wiring on 3870

    I recently stumbled across my galvanic isolator while I was running new wire for my shore power inlet. My boat is burning through zincs every six months and I'm thinking I need to figure out my bonding system. A previous install of an inverter on my boat was clearly done by somebody that did not understand what they were really doing. This person was great with neat and tidy wiring but they created a really unsafe condition where both of my shore power inlets were joined at the selector switch and both lines on my boat ran off a single inlet. The previous install had both shore power lines grounded at the earth bus, not the galvanic isolator and I suspect maybe that is why I'm eating through zincs so fast.
    Click image for larger version

Name:	Galvanic Isolator.jpg
Views:	185
Size:	105.0 KB
ID:	552503
    Could this configuration possibly be right? I have no idea why the hot water heater would ground at the isolator as opposed to the earth bus. Neither shore power lines were connected to the isolator either, they both went straight to the earth bus. Why would secondary ground bus be connected to the input side of the isolator? I'm planning on connecting my new shore power line ground to the input side of the isolator but I'm also not even sure if the bonding system is attached to the isolator anywhere. Going to have to go down into the bilge to see if I can find any green wires that run from the bonding system up into the boat.

    #2
    The paragraph below is from a EE boat owner friend:

    "The galvanic isolator is a very simple device. It allows AC to pass through, but with the use of two diodes in series, in each direction, the isolator blocks any voltage (AC or DC) with voltage less than about 1.4 Volts, either polarity (they say about 1.1 volts, but they are conservative in their rating, as typical silicon diodes need to be forward biased about 0.7 volts before they will conduct). All this means is that there needs to be an AC fault greater than 1.4 volts for the galvanic isolator to conduct the fault current to the AC safety ground on shore. There is also a capacitor across the diodes that will also pass (depending on its size, but probably small) AC currents to shore ground." What this means is that tiny stray currents are blocked but a major AC short will pass to shore ground.

    From the Guest installation manual:
    The Guest Model 2530P, 2550P or 2460P Galvanic Isolator should be mounted in the boat hull adjacent to the shore power connector so that no part of the grounding system bypasses the isolator

    Installation is shown in the diagram below:

    It's possible that the "input" side of your isolator is simply a collection point for various grounds. This would seem to violate the , "No part of the grounding system bypasses the isolator".

    The positive battery connections are for the monitoring system.

    If you're really uncertain about the wiring and even less certain about the skills of the installer, you may be better off starting over than trying to troubleshoot what you have.

    Good luck. Other people's wiring can make strong men weep.

    Click image for larger version

Name:	galvanic isolator wiring diagram.JPG
Views:	180
Size:	2.37 MB
ID:	552505Click image for larger version

Name:	Galvanic isolator internal wiring.jpg
Views:	166
Size:	239.3 KB
ID:	552507




    100T MMC 2307794

    Comment


      #3
      Yes Highland, that seems to verify what everything else is telling me too, that the ground wire from my shore power inlet must be connected to the isolator. I found another thread here from somebody that was equally baffled as to why Bayliner would have grounded the hot water heater there. I don't really think the generator should be grounded at the isolator either but as mine doesn't work anyway I'm not too worried about it. At least I'm starting to figure things out and I think I'm on the right path to making things better.

      Comment


        #4
        Yes Bryguy from you picture the ground wires are incorrect. The input side should only be the ground wire coming in from the marina shore power. All other wires should on the output side. I had this problem where my zincs were shiny all the time and it also affected the props. The brass went a pink color which means they are brittle.

        Hugh
        1990 3888
        Hino 175 Diesels

        Comment


          #5
          Based on what you've discovered regarding the galvanic isolator, generator, and inverter, I recommend that you have an experienced marine electrician check your boat out and make the necessary changes.
          1999 3788, Cummins 270 "Freedom"
          2013 Boston Whaler 130 SS
          Anacortes, WA

          Comment


            #6
            I have shaft anodes, trim tab anodes and one large anode mounted on the external transom midline. The shaft and trim tabs anodes lasted anywhere from 4-6 mos. since I’ve had this boat, about 7 years now. I kinda thought that time was about normal thus I’m not sure you have an issue to worry about.
            Jim Gandee
            1989 3888
            Hino 175's
            Fire Escape
            [email protected]

            Comment


              #7
              When I started resurrecting my boat one of the projects I did right away was completely replace the bonding system. It had the original 12 or 14 gauge green wire running around the engine room with everything daisy chained together. A break anywhere in the line would mean everything after the break was no longer protected. I added a bus bar to the rear transom and ran #8 green from everything to the bus bar to include the grounds from the engines. This also includes a single through bolt from each trim tab which is also connecting into the bonding system. I have shaft zincs, disks on each trim tab and rudder as well as the large plate on the transom. Since doing this I get a little more than a year out of the disks, a little less on the shaft zincs and the plate has been on there coming up on three years.

              As far as the isolator itself, the input side is only the green from the shore power plug and output is only green to ground bus bar of the breaker panel. Nothing else. My bonding system is also connected to the ground bus bar of the breaker panel.

              Paul
              US Army (Retired), Federal Way, WA

              1990 Bayliner 3288 - the "Janna Lea"
              MMSI: 338181912

              Comment


                #8
                your galvanic isolator only is for the ground... a better option is a true isolation transformer like the Charles G2, which will truly isolate you from other 'dirty' boats around you. I have installed it myself in the starboard lazarette on my 45 and it works great...would recommend it. Ken

                Comment


                  #9
                  I change our zincs on our 38 every 6 months and don't have an isolator. I buy my zincs from boatzincs.com and then hire a diver to install them and scrub my bottom.

                  Comment


                    #10
                    Originally posted by Johnny_Vintage View Post
                    I change our zincs on our 38 every 6 months and don't have an isolator. I buy my zincs from boatzincs.com and then hire a diver to install them and scrub my bottom.
                    A galvanic isolator prevents stray current corrosion if there are stray currents from other boats at the marina. Otherwise, it won't do anything.
                    1999 3788, Cummins 270 "Freedom"
                    2013 Boston Whaler 130 SS
                    Anacortes, WA

                    Comment


                      #11
                      BryGuy,

                      My 1989 3888 isolator is wired exactly the same as yours. I presume it was done that way from the factory. Same location, same device.

                      James
                      1989 Bayliner 3888, 175 Hinos,
                      Hurth 630's Onan 8kw MDKD
                      Lowrance Electronics!
                      MMSI
                      316030379
                      VHF
                      CFA 2587
                      Boating on Georgian Bay & the North Channel
                      Completed the Great Loop 07/25/19
                      AGLCA #8340
                      MTOA# 7469

                      Comment


                        #12
                        Thanks all. Maybe 6 months is all I can expect from my zincs but I'm still going to investigate my bonding system further. Zincs every 6 months seems awfully fast compared to what I hear from other boat owners (people that own different makes and models). Next step is to test this old isolator to see if it is still functioning properly. If all the 3870's were wired incorrectly out of the factory that could explain why they burn zincs so fast. The galvanic isolator does not protect against stray current, it keeps the ground wire from your marina shore power from connecting you to the grounds (and hence bonding systems) of all the other boats in the marina. If this does not happen, you can become the sacrificial anode for any unprotected boats on shore power that are generating galvanic current due to the connection of dissimilar metals in an electrolyte (salt water). The isolator cuts off this low voltage current and prevents it from flowing through to your bonding system. It is baffling to me why the shore power grounds don't run to the isolator. Our water heaters are aluminium, maybe the Bayliner techs were confused about what the isolator was for. I just don't understand why they grounded the water heaters there.

                        Comment


                          #13
                          Did the 38's come with a galvanic isolator? I've had my 86 for 10 years and have not seen one. Where were they installed?

                          Comment


                            #14
                            Mine is located on the backside of bulkhead above the refrigerator. If you remove the AC distribution panel you’ll see it. If you blink you might miss it, it’s surprisingly small.
                            P/C Pete
                            Edmonds Yacht Club (Commodore 1993)
                            1988 3818 "GLAUBEN”
                            Hino EH700 175 Onan MDKD Genset
                            1980 Encounter Sunbridge "Misty Blue" (Sold)
                            MMSI 367770440
                            1972 Chevrolet Nova Frame off Resto-mod in the garage
                            Boating on the Salish Sea since 1948

                            Comment


                              #15
                              I'll have a look see.

                              Comment

                              Working...
                              X