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AC Wire size

Discussion in 'Big Boats' started by Wanderwind36, Aug 4, 2017. Add this thread to a FAQ

  1. Wanderwind36

    Wanderwind36

    Joined Feb 5, 2015
    3 posts, 0 likes
    Catalina 36
    US Olympia, WA
    Looking to determine the ac wire size from the inlet receptical to the service panel on a 1987 C36. The ground lug arced and got hot frying the shore power cord, inlet receptical at the boat, and melting and burning the ac wire for a distance from the receptical. Have replaced the power cord and inlet receptical at the boat and will run new wire from the inlet receptical to the power panel. The 30 amp Marinco shore power cord is 10 gauge but I believe the marine grade wire from the receptical to the power panel is 12 gauge. It looks the same size at the power panel as all other wire running to the power plugs which I am sure is 12 gauge, but there are no markings that I understand to indicate the wire size. My ac wiring diagram for the boat outlines the layout but does not identify wire size like the dc wiring diagram does. Anyone know the wire size for the panel feed from the inlet receptical to the power panel on the C36, or can confirm that it is in fact 12 gauge?
     


  2. jssailem

    jssailem

    Joined Oct 22, 2014
    2,644 posts, 483 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    I like to refer a question like this to MaineSail. His website is full of very useful info.
    From his site here is a snip it. http://www.pbase.com/mainecruising/installing_a_smart_plug
    Untinned Wire
    Here is a prime example of where tinned marine wire may have bought this owner more time. A new run of 10/3 triplex wire was in order. The black oxidation on this wire can also create high resistance. When in doubt it is best to also replace the feed wire from the new AC inlet to the AC panel..
    If your wire run between the AC shore inlet to the AC main breaker, at the AC panel, is more than 10' wire feet, not as the crow flies, then you will want to install a second 30A or 50A double pole breaker. This breaker needs to be interrupting WHITE/NEUTRAL & BLACK/HOT, and be located quite closely to the AC shore inlet.​

    I would put 10AWG Marine 3 wire from your shore Inlet to the ACpanel. No more than 10ft of wire.
     


  3. Wanderwind36

    Wanderwind36

    Joined Feb 5, 2015
    3 posts, 0 likes
    Catalina 36
    US Olympia, WA
    Think I found the answer in a product description for 12/3 AWG Triplex Tinned Marine Ware that notes "that the 12/3 wire is rated for running 15 amp and 20 amp circuits from the main panel to your outlets, and is NOT rated for running 30 amps from the shore cord inlet to the main panel. You'll need 10/3 for that." I still think the original wiring from shore cord inlet to the main panel is 12/3, but it looks like I will be going with 10/3 which only makes sense.
     


  4. jeepbluetj

    jeepbluetj

    Joined Jan 18, 2016
    269 posts, 57 likes
    Catalina 30
    US SoCal Dana Point
    Yup. 10/3. Use tinned marine wire.

    I hope it wasn't actually the GROUND lug that overheated, but either the neutral or hot. If it was indeed the ground, something seriously went wrong with the wiring somewhere - i.e. ground should never carry current except in a fault condition.

    The L5-30 connectors are a less-than-optimal design, imho. They're obviously crappy enough that smartplug stays in business. Of course, a smartplug retrofit is pretty expensive.
     


  5. BigEasy

    BigEasy

    Joined Jun 21, 2004
    619 posts, 74 likes
    Beneteau 343
    US Slidell, LA
    The smart plug retrofit was one of the best mods that I have done to my boat. The convenience factor is enough to justify it alone; however, once you see the robust design of the individual terminals, you can appreciate the engineering that went into the plug. I plan to add another circuit for my air conditioner; have already purchased the AC panel, double pole breaker, and another smart plug. Thanks for the wire recommendation; I still have to purchase the wire.
     


  6. jssailem

    jssailem

    Joined Oct 22, 2014
    2,644 posts, 483 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    Yes the
    :plus::plus: worthy of the cost.
     


  7. Wanderwind36

    Wanderwind36

    Joined Feb 5, 2015
    3 posts, 0 likes
    Catalina 36
    US Olympia, WA
    Yes, miss spoke, it was the white neutral leg that got hot, not green GROUND. Thanks for the recommendations.
     



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