negative wiring

Discussion in 'Electrical Systems' started by bertho, Nov 28, 2011.

  1. bertho
    Joined: Aug 2006
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    Location: asean archipelago

    bertho bertho

    Guys,
    Just wondering:
    for positive, no questions, as they come from the fuse/switch for each destination , it's one dedicated wire
    but for negative wires, why they have to come back to the main panel, as they will be connected together there, why we don't have few bus-bar in some place of the boat and connect all negative there to avoid long negative wire to be back in one single place ? if the " local" negative bus bar have proper size, i don't see really why is not possible.
    any electrical or ?? issues
    thanks
    rgds
    bertho
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    You can put a negative buss bar any place that is convenient. There is no requirement to have it at the panel. However, if you use duplex wire, it will end at the panel and makes it easy to connect.
     
  3. Poida
    Joined: Apr 2006
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    Poida Senior Member

    Although Gonzo is correct. Faults normally occur at electrical connections.

    Keeping the number of buss bars to a limit may be advisable. ie. I wouldn't run the return from one buss bar to the next etc. until you get back to the main.

    If there was a fault it makes it more difficult to find.

    Poida
     
  4. bertho
    Joined: Aug 2006
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    bertho bertho

    the purpose was to make it simple and less wires going back to the main panel, with 2 or 3 "secondary" busbar well located, the total length of negative wire for light and small items can be much less than to have all of them returning all to the main panel.
    thanks
    bertho
     
  5. keysdisease
    Joined: Mar 2006
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    Location: South Florida USA

    keysdisease Senior Member

    What you describe is common practice. For example on a small runabout or center console there will be a negative busbar aft for the sternlight, bilge pump, trim tabs, etc.

    Steve
     
  6. MechaNik
    Joined: Jan 2011
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    Location: Greece, Italy

    MechaNik Senior Member

    If you don't mind having wires going off in different directions then go ahead. I like my power to come down the same cable preferably through a dual pole breaker, which in turn is connect to a positive and negative bus. A few well placed distribution boxes makes this tidy.
    This is an evolution from having the ship as a ground and running only positive cables. What you suggest is somewhere in between. It all works, but down the track one will be more appreciated.
     
  7. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Twin pole breakers with distribution centers around the ship is normal practice and saves much wire. One breaker and two wires controls... "Foreship lighting". Once at the foreship, the lighting branches off to each individual light circuit from the distribution center.
     
  8. rxcomposite
    Joined: Jan 2005
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    rxcomposite Senior Member

    NAV/COMS equipments needs to have "star" or single point connection to avoid "ground loops" due to different impedances that makes the electronics go crazy. A short and thick bus bar is permitted in the panel to accomodate all the return wires. For others, it is not so important but I do not know the general practice as I have read different instructions for ground plates and engine groundings.
     

  9. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Normally nav gear is separate from the general ships electric distribution circuit ... Typically a straight run from breaker, via adedicated cable trays , into dc to dc converters, then nav gear.

    It possible that there is a more modern approach, but this is what Ive observed for many years on professionally wired vessels.
     
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