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Power mains question: wire gauge

Discussion in 'Misc Electronics' started by DaveC, Dec 28, 2012.

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  1. DaveC

    DaveC Guest

    Air compressor 1/2 hp motor rated 220v (2-wire, not 3-phase) @ 15A. Distance
    from load panel ~100 ft (as the conduit runs).

    15A can be handled by 14 gauge, but I'd normally go with 12 gauge due to
    start current.

    With such a distance, is it recommend to up-scale the wire to 10 ga?

  2. SoothSayer

    SoothSayer Guest

    Cant hurt. It would definitely help, in fact. multiple #14s to make
    each #10 would work better, keeping each segment electrically separated
    except at the nodes, giving a sort of Litz effect. At that gauge, you
    can get SPC too (Silver Plated Copper), reducing ohms per foot without
    increasing gauge above #10.

    And you want a #12 return run for ground fault carriage too.
    A single piece would pop a breaker.
  3. Phil Allison

    Phil Allison Guest


    ** Giant HUH ??

    Such a motor normally draws around 3 amps.

    .... Phil
  4. Guest

    considered what the skin deepth at 60Hz is?....

  5. Bill

    Bill Guest

    There is s thing called "voltage drop". Voltage will drop in a wire
    running a long distance, sometimes so much, the device at the end will
    not operate!

    The amount of voltage drop depends on the voltage, the type of metal
    used for the wire (copper / aluminum), the wire size, and the load in
    amperage at the end of that wire.

    The internet has made this easy for you. Just search for the

    Voltage Drop Calculator
  6. DaveC

    DaveC Guest

    Until the motor or compressor is replaced with a larger unit. Then
    That's a good idea. I'll talk it over with the owner.

    But for now I want to settle on what size conductor to use if it's just to
    supply this one compressor.

  7. Guest

    If it's 1/2HP, now, it's unlikely to grow to >5HP.
    Run several #12s, instead, when needed. It's cheaper.
  8. notme

    notme Guest

    Run several #12s, instead, when needed. It's cheaper.

    Pull additional #12s in the future? I've had bad experience pulling
    additional conductors in a conduit with existing conductors.

    If I misunderstand your statement, please try again. ;-)

  9. MrTallyman

    MrTallyman Guest

    No. A bundle of a few 12s will make a nice oversized #10.
    The finished 'wire' will be stronger and more flexible too.

    Of course, the return has to match. So you pull all 7 at once.

    Two sets of 3 #12s and one #12 fault return. Seven wires.
  10. Guest

  11. Guest

    I've seen a *lot* of 1/2HP motors used for power tools that can be
    wired either way.
    Rather irrelevant.
    I always do it the right way. The "right way" depends on the
    situation. I guess the "right side" is universal, though, but it's
    also right.
    It's a *lot* cheaper. #6 is a PITA to work with. No thanks!
    Now you're throwing in random costs.
  12. Guest

    OK, 300K.
  13. Tom Biasi

    Tom Biasi Guest

    How about run what you need now with a pull string included?
  14. Guest

    Sure. Most small fractional horse induction motors can be.
  15. Guest

    I think we have a winner!
  16. Guest

    Hey, you never know how big of a compressor you might need.
  17. rickman

    rickman Guest

    100 feet of AWG 6 will set you back some C-notes. That's an expensive
    investment if you don't need it.

  18. SoothSayer

    SoothSayer Guest

    What utter idiot suggested #6?
  19. It's also a sweaty PITA to pull.. ( I ran some to a manly (for single
    phase) compressor and kiln).

    Best regards,
    Spehro Pefhany
  20. Jasen Betts

    Jasen Betts Guest

    a larger compresser is likely to have a soft start where the pump
    compression is releived come on until it's up to speed.
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