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Thread: Power and Ground Connection

  1. #1

    Join Date
    Mar 2014
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    Lake Isabella, CA
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    99

    Default Power and Ground Connection

    I am debating using an in-line connector at the back of my panel for 12V and Ground. Ground going to the engine block, 12V going to the starter 12V connection. Any thoughts on the pros and cons of using a connector instead of direct wiring. All of my other signals go through connectors.

    Thanks
    tom

  2. #2
    Senior Member
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    Jul 2011
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    milwaukee wi
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    490

    Default Re: Power and Ground Connection

    Those connectors will have to handle a lot of current. Must be some super connector.

  3. #3
    nlappos's Avatar
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    Jan 2015
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    Guilford
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    17

    Default Re: Power and Ground Connection

    The typical KF or Avid has only about 15 amps at 12v, so power amperage isnt the issue really. The real issue is failures and how many eggs in the basket.
    Here is a pretty good discussion of the basic electrical layout with a redundant essential bus:
    http://www.aeroelectric.com/articles/avmaster.pdf

    for the bus bars, I use these:
    http://www.amazon.com/gp/product/B00...ilpage_o07_s00
    Last edited by nlappos; 02-01-2016 at 05:33 PM.

  4. #4
    Senior Member
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    Nov 2008
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    KDKB (Dekalb, Illinois)
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    Default Re: Power and Ground Connection

    More than likely you will NEVER take it apart, so likely the effort to make
    it serviceable will not really be worth a lot. However these are our hobbies,
    so no reason to not do it either.

    Jeff

  5. #5
    Senior Member jmodguy's Avatar
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    Jul 2014
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    Carmel, IN
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    Default Re: Power and Ground Connection

    I will be using connectors on my firewall. One for starter and alternator and another for everything else.
    Why? Because I don't like multiple holes with stuffing tubes, firesleeve and big globs of RTV smeared all over everything.
    Connectors looks neater, function just as well and makes maintenance and troubleshooting a whole lot easier. Build your airplane to fly, but also build it to work on.
    The starter and alternator will require a #4 and #8 wire respectively. Engine ground should also be a #4 wire.
    Most sensor wires can be a 20 or 22 ga wire. Sensors typically do not require 18 or 16 ga wire unless it is pulling gobs of current. If your sensor is pulling 8 to 10 amps you should probably consider something else.
    Injectors for FI engines typically require 18 ga wire.
    Think of it like this; if you use heavier wire than needed you are adding weight that is not needed.
    As for EGT and CHT probes, if you are worried about the small amount of error that may be induced by not using alumel and chromel contacts then you can run these through a connector as well. You probably won't notice the difference on typical GA systems.
    Do not use the cheap "stamped and rolled" contacts you typically use on computer cables and such. Use quality contacts to save yourself some grief and head scratching.
    I will be using 38999 series III circular connectors. You say; "but aren't they expensive"? Hmmmm.... You just spent $30,000 on a kit plane, $15 - $20,000 on an engine, $4000 on avionics and you are groaning about $200?!
    Regards,
    Jeff
    Jeff
    KF 5
    340KF

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