Two spreader lights from a single pair of wires

Discussion in 'Electrical Systems' started by ayates, Nov 25, 2011.

  1. ayates
    Joined: Nov 2011
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    Location: Merrickville, Ontario

    ayates New Member

    I wondering what was the best practice was when wiring a pair of spreader lights (40' up a mast). I assume only a single two conductor cable is run up the mast, and then is split into two. My best proposal would be a waterproof junction box to split the main cable into two (say with a terminal strip), and then adhesive lined butt connectors for the lamp connections.

    Any better (or cleaner) method that the above? Its just that using a junction box seems over kill, as would running four wires up the mast. Or is it best practice to run separate conductors for each light? i.e. a four conductor cable.


    Thanks,

    Allan.
     
  2. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    If "adhesive lined butt connectors" means heat-shrink connectors, then it yes - it will give a good waterproof joint. An IP67 junction box is a solution which ensures that all the electrical connections inside will remain fixed and dry even in case of an occasional immersion of the mast tip (though I hope you'll never experience that event ;) ).
    The difference in cost between a 4-wire and a 2-wire distribution for a 40' length will be presumably something like $10-15 in favour of the latter. The 2-wire distribution is also simpler, easier to install, neater and will add less weight up at the mast (though it is really small stuff we're talking about), so I would personally prefer it over a 4-wire system for such a simple application.

    For a more general info about electrical wiring, you could take a look at this article: http://www.boatus.com/boattech/casey/05.htm

    Cheers
     
  3. PAR
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    PAR Yacht Designer/Builder

    You don't need a junction box. Just run two wires up the stick, then over to one light, make the connection, then over to the other light for the same. No need for a "T" style of connection, as it just adds to the likelihood of a failure. Of course, on one side you'll have two wires going into the light and two wires coming out to the other light, but the benefit of this is you only have connections inside each lamp assembly where they'll be protected.
     
  4. Submarine Tom

    Submarine Tom Previous Member

    I couldn't agree more PAR.

    -Tom
     
  5. daiquiri
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    daiquiri Engineering and Design

    Ok for PAR's advice. But I would still use at least one junction box near the base of the mast, or near the mast partner. In that way wires can be easily disconnected when mast is to be removed for maintainance, transport or for whatever other reason.
     
  6. PAR
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    PAR Yacht Designer/Builder

    Rather then the junction box at the base of the mast, use a plug and socket. It's less bulky, easier to install and you just un-plug the lights when you drop the mast. A socket can accept a boot easily, unlike a junction box.
    [​IMG]
     
  7. viking north
    Joined: Dec 2010
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    viking north VINLAND

    When making electrical connections that are exposed to enviormental corrosion I always use a rubber volcanizing tape (basically same as rigging tape) and give it a coating of 5200 caulking. When attaching to connectors inside light or other casings I also give these a coating, likewise the coax screw on connector to the VHF antenna. Most important always use marine tinned conductors otherwise you're just wasting money and asking for trouble.
     
  8. PAR
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    PAR Yacht Designer/Builder

    Dielectric grease is the best thing you can do to exposed connections. Protective boots and connectors have gotten very good in recent years at preventing moisture issues.
     
  9. Poida
    Joined: Apr 2006
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    Poida Senior Member

    Wiring as Par said but not putting in the plug at the bottom of the mast. Somewhere before the mast put in a "service loop" this is just an extra length of cable should you need it at a later date.

    If you need to remove the mast, then you can cut the cable and insert a plug should the need ever arise.

    Plugs are harder to keep water out of than a junction box. With a junction box the cables both enter at the bottom, the connectors are taped with galvanising tape as previously mentioned, and the hole at the bottom of the junction box sealed with silicone.

    But don't bother until you have to remove the mast.

    Poida
     
  10. viking north
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    viking north VINLAND

    One thing I never do with wiring that runs up the mast is never break my communications coax cable. The cables feeding any and all mast top mounted antennas are one piece from the antenna to the transeiver. A splice connector results in a 3DB.(half power) loss along with the constant possibility of corrosion problems. It is also very important again to use only marine coax and go to extremes to keep that outer cable covering sealed 100% against the weather, especially at the cable to connector and connector to antenna joints. Don't forget your antenna connection drip loop.It is amazing how fast dampness will travel along the braided outer shield if the covering is damaged. This results in a change in the coaxes impediance causing a mismatch resulting in poor signal transfer at best to transmitter damage at worst. Another important function one should perform periodically is to tune the antenna using an SWR meter. I have one mounted next to my transeivers and check the system every week or so. More of a hobby than a need but I like a well tuned comm. set up.
     
    Last edited: Dec 13, 2011
  11. PAR
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    PAR Yacht Designer/Builder

    I wouldn't bother with a service loop on a 12 VDC power connection, just a drip loop and well sealed plug assembly or bulkhead connection. On most boats the stick has to come off periodically for layup, inspection, repairs, etc. and the service loop gets cut anyway.

    The same would be true with a coax connection, just use a bulkhead connection or female connector. Naturally, you'll want to wrap this type of connection with Coax Seal, which is a moldable, putty like tape.
     

  12. michael pierzga
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    michael pierzga Senior Member

    Most mast cables are poorly installed. When a cable exits the spar to service an antenna or equipment , its exposed to UV degradation. The cable cover rapidly deteriorates. Spiral wrap or other defenses on exposed cables extends the service life of exterior cables.
     
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