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AC wiring in N28-2

Discussion in 'Newport' started by MitchK, Dec 6, 2017. Add this thread to a FAQ

  1. MitchK


    Joined Sep 22, 2017
    38 posts, 5 likes
    Capital Yachts Newport 28
    US Burbank, Wa Burbank, WA
    All, as I was going through the boat over the past several weeks, I discovered the AC wiring leaves a lot to be desired. So much so, I refuse to use it until I can get it re-wired properly. I had found the nut/bolt and tape splices up in the bow, but what I have discovered at the main breaker has me scratching my head. There are three wires coming from the shore power plug, but when they get to the factory push button breaker, they connect the common and ground together, and have the hot going to the breaker. I think this is not a good thing. Anyway, I have already ordered up some 12-3 marine wiring, and some 10-3 for the run from the shore power plug to where the new Paneltronics AC panel will be installed. I will also be ordering a galvanic isolator to help eliminate any ground currents. Fortunately, the N28-2's AC circuit needs are pretty minimal, so I am only installing a three circuit panel. Anyway, thought the wiring issue might be something others might want to be on the lookout for.


  2. Ron20324


    Joined Jan 22, 2008
    5,717 posts, 396 likes
    Beneteau 323
    US Annapolis MD
    AC from the shore power should never have the ground and neutral together on the boat. That should only occur at the shore-side AC breaker box in the marina.

  3. Maine Sail

    Maine Sail Moderator

    Joined Feb 6, 1998
    10,407 posts, 339 likes
    Canadian Sailcraft 36T
    US Casco Bay, ME
    Very good plan.

    You are wise to be scared as this is absolutely not how a boat is to be wired for AC. Both AC hot/black and AC neutral/white are to be interrupted by a breaker.

    AC grounding/Green and AC neutral/white are not to be connected on board unless you are actively inverting or running a generator. When using just shore power you can not have an AC Neutral and AC Grounding bond on-board.

    10/3 is good for a 30A feed but if that wire is longer than 10' you'll need a breaker at the inlet end as well. 12/3 is fine for 20A circuits and it never hurts for it to be larger if you decide on 15A circuits.

    I would strongly advise an ELCI main breaker and then 5mA GFCI receptacles for the branch circuits. ELCI's are required by current ABYC safety standards as are GFCI's for galley, head, engine spaces and weather deck areas. A best practice is to protect everything you can with a GFCI including a water heater or battery charger.

    Galvanic isolators only protect against galvanic current (the current created by dissimilar metals in an electrolyte) and do not protect for electrolytic/stray-current. The best approach is an isolation transformer if you really want to protect the vessel but this would be a lot of weight and expense for a 28' boat.

    The horrible level of AC wiring on boats is starting to rapidly show its ugly head now that the NFPA / NEC requires marinas to have ground fault protection.

    Here is a good basic AC diagram to work from. If you do not have a reverse polarity indicating panel then AC branch breakers should be double pole.


  4. MitchK


    Joined Sep 22, 2017
    38 posts, 5 likes
    Capital Yachts Newport 28
    US Burbank, Wa Burbank, WA
    Thanks for the various replies. I did order a new panel with reverse polarity indicator, and reverse polarity disconnect. It has a three section main breaker. Two for the hot and common, and the third that is voltage activated ( I think) so if it senses a reverse polarity, it will trip the main. The panel only has three branch circuits. In my N28-2, the only AC circuits are a few standard receptacles (4 or 5 I think). I plan on wiring the receptacles to one branch, a second branch circuit for the marine battery charger, and a third branch for future expansion. The panel will be mounted in the same place as the original. Just need to open the liner up to fit. I have a small light also mounted on the liner that I may have to move to make enough room. Anyway, here is a picture of the panel I purchased, and where it will be mounted.

    Attached Files:

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