Bonding clarification

Discussion in 'Electrical Stuff' started by Carpediem44DB, Dec 15, 2021.

  1. Carpediem44DB

    Carpediem44DB Well-Known Member GOLD Sponsor

    Aug 18, 2015
    Sanfransico Bay area
    2000 Carver 506
    2006 44 DB Sedan Bridge
    Volvo TAMD 74 P
    I began my winter project list on the 506 today. I have five weeks off and have a nice list of things to take care of over winter break.
    I replaced the engine anodes and did a general visual condition inspection. I noticed several green bonding wires attached the to the engine blocks, a little surface corrosion so put that on the list of things to do to clean up and treat. I moved on to the 21 KW Kohler Generator to replace the anode in the heat exchanger and could not locate one. I looked in the parts book for the generator and found none listed. Seems odd. I then looked for a bonding wire to determine it's condition and also found no green bonding wire. There is one on the thru hull to the generator but non on the generator itself. There is a lug on the engine mount that looks like an ideal place to have a bonding wire but I am wondering if there is a good reason there is non installed. I noticed also there is no bonding wire to the bow thruster either. Am I missing something?
    Carpe Diem
     
  2. dtfeld

    dtfeld Water Contrails GOLD Sponsor

    Jun 5, 2016
    Milton, GA
    410 Sundancer
    2001
    12" Axiom and 9" Axiom+ MFD
    Cat 3126 V-Drives
    There is a difference between bonding and a chassis ground. Bonding is the electrical connection between a anything metal that also touches sea water and is usually a green wire. They provide a path for ground-fault currents, prevent touch-voltages on metal surfaces and provide a path for stray currents.

    Chassis grounds are part of the DC electrical system. Those are usually black.
     
  3. Carpediem44DB

    Carpediem44DB Well-Known Member GOLD Sponsor

    Aug 18, 2015
    Sanfransico Bay area
    2000 Carver 506
    2006 44 DB Sedan Bridge
    Volvo TAMD 74 P
    Thanks, I have a clear understanding of what the green and black wires are for, I am wondering why the bow thruster and genset are not included in the bonding circuit. Also wondering why the Kohler Genset heat exchanger has no anodes like the Onan does. The heat exchanger is not a typical inline pipe style like the Onan, it is similar in design as the main engine exchangers mounted to the engine block.
    CD
     
    dtfeld likes this.
  4. ttmott

    ttmott PhD in OCD TECHNICAL Contributor GOLD Sponsor

    Apr 3, 2012
    Space Coast Florida
    2006 52 Sedan Bridge
    Cummins QSM11
    Bonding, AC grounding, DC Negative/Ground, and AC neutral are all quite different in function, but all share a common copper path for the most part. When on generator power the AC neutral is connected to the AC ground as the generator is classified as a "power source".
    Regardless, all metallic components (engines, generator, through hulls, thrusters, water heater, etc, etc.) on the boat need to be Bonded with an electrical copper path to the external anode and (if your boat has one) the ground reference plate. It is the green wire network that is used to do this as you know.

    Two reasons - one, to ensure galvanic corrosion is checked and the anode is the sacrificial metal and two, there is a path to water for hazardous (lightning for example) currents.
    The AC power ground is different however; It's purpose is to provide an electrical path to safely route the hazard back to the electrical source not to the anode and water. This is important for the proper function of the GFCI devices also.
    The AC neutral must be bonded to the AC ground at all power sources such as inverters, generators, and isolation transformers.
     
    PartnerShip likes this.
  5. Carpediem44DB

    Carpediem44DB Well-Known Member GOLD Sponsor

    Aug 18, 2015
    Sanfransico Bay area
    2000 Carver 506
    2006 44 DB Sedan Bridge
    Volvo TAMD 74 P
    So it sounds like I should add a green bonding wire to the frame of the genset and also to my bow thruster. As I mentioned in a different thread, I found a green bonding wire to the Bridge AC unit was not connected and the pan is severely corroded as a result. I do have some light corrosion on the genset sound shroud perhaps due to the lack of bonding. I looked all over and do not see a loose segment of green bonding wire in the area of the genset so I will run one from the thru hull lug that is bonded.
    Thanks for the input. Does anyone else run a Kohler Genset? Curious as to why there is no anode on the fresh water exchanger. There is a plug in a fitting that I could probably install an anode in. I have a good local Kohler dealer/service guy, I'll give him a call and see what he knows about it.
    Carpe Diem
     
    Nater Potater likes this.
  6. dtfeld

    dtfeld Water Contrails GOLD Sponsor

    Jun 5, 2016
    Milton, GA
    410 Sundancer
    2001
    12" Axiom and 9" Axiom+ MFD
    Cat 3126 V-Drives
    I would read the installation manual to see what was recommended as far as bonding the generator. It might not be necessary, and at worst detrimental.

    as far as the heat exchanger, I would think it would have a anode, but it could be made of a material that doesn’t require one.
     
  7. BlueYonder

    BlueYonder Active Member

    234
    Jan 12, 2015
    Chesapeake Bay
    37
    QSC 8.3 600
    Your bow thruster and genset most likely have their own zincs and do not need to be bonded. Corrosion on your genset cover is probably due to water or salt air. A bonding system will prevent electrolysis, not corrosion caused by rusting.
     
  8. Carpediem44DB

    Carpediem44DB Well-Known Member GOLD Sponsor

    Aug 18, 2015
    Sanfransico Bay area
    2000 Carver 506
    2006 44 DB Sedan Bridge
    Volvo TAMD 74 P
    My thruster does have its own anode for sure and I figured perhaps the reason it was not bonded. The genset does not, at least non that I can find on the heat exchanger or in the parts book. Kind of a head scratcher. Of course we are talking about a Carver:p
     
  9. ttmott

    ttmott PhD in OCD TECHNICAL Contributor GOLD Sponsor

    Apr 3, 2012
    Space Coast Florida
    2006 52 Sedan Bridge
    Cummins QSM11
    The whole premise on bonding and grounding is so the entire boat raises and lowers equally in electrical potential, in that, there is no differential in voltage between any of the metallic components on the boat ever. Then, and again, the galvanic corrosion is absorbed by the hull anode.
     
    PartnerShip likes this.
  10. SKybolt

    SKybolt Well-Known Member GOLD Sponsor

    Nov 11, 2014
    Kent Narrows, MD
    1988 460 EC
    Detroit 6v92TA
    (Low profile's)
    Alison Gears
    Westerbeke
    12.5kw Genset
    @Carpediem44DB Is your generator connected through an isolation transformer? If it is then check for the bonding wire on that, but there should not be one on the generator when using an isolation transformer. I only ask this because I saw another Carver that had this type of wiring setup.

    To @ttmott point, all metal on the boat should be bonded, including your bow thruster. Normally on generators the neutral and green bonding are connected, and the ac neutral is switched (lifted) at the ac panel. But in the case of an isolation transformer there should not be a ground. I am not sure why some of the larger boats are wired this way as the boat when disconnected from the dock is now isolated. I can only think it is for the use of multiple generator connections.

    EDIT: Having an anode (zinc) does not replace the need for bonding. Zincs allow the stray currents to eat away at them and not the metal they are attached to. Bonding helps neutralize the stray currents. The two work in concert together, one does not replace the other.
     
    Spark600 and dtfeld like this.
  11. Carpediem44DB

    Carpediem44DB Well-Known Member GOLD Sponsor

    Aug 18, 2015
    Sanfransico Bay area
    2000 Carver 506
    2006 44 DB Sedan Bridge
    Volvo TAMD 74 P
    @SKybolt, I will check my Isolation transformer for the presence of a bonding circuit. I know the Genset and thruster have no bonding. I will have to trace wiring to see if the genset is wired to and thru the Isolation transformer. I think there is only one on the boat for the two 50 amp 240 volt shore power circuits.
    Carpe Diem
     
  12. ttmott

    ttmott PhD in OCD TECHNICAL Contributor GOLD Sponsor

    Apr 3, 2012
    Space Coast Florida
    2006 52 Sedan Bridge
    Cummins QSM11
    It is important that on a boat with an Isolation Transformer that the AC power neutral/common is bonded to the AC power ground at one location. Typically that is the common ground buss. That buss is then connected to the AC power neutral buss, DC negative buss, and the bonding system buss'. Your generator's neutral and ground should not be connected together at the generator in this configuration. Some drawings for reference -
    upload_2021-12-22_6-9-45.png
    upload_2021-12-22_6-10-28.png
    upload_2021-12-22_6-11-48.png
     
  13. Carpediem44DB

    Carpediem44DB Well-Known Member GOLD Sponsor

    Aug 18, 2015
    Sanfransico Bay area
    2000 Carver 506
    2006 44 DB Sedan Bridge
    Volvo TAMD 74 P
    Thanks Tom, I'll compare this to the Kohler/Carver diagrams. This is one thing I miss the most about My Sea Ray 44DB, The wiring diagrams in the owners manual were extraordinary. Carver, not so much:(
     
  14. Nater Potater

    Nater Potater Well-Known Member GOLD Sponsor

    Oct 19, 2020
    Southwest Idaho
    1992 300DA Sundancer
    Twin Merc Alpha Gen II I/O's with 5.7 V8's
    Also running a Kohler, but too new to this rig to know anything. 'Very curious to hear what you find out.
     

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