Derating Confusion

Discussion in 'Electrical Forum discussion & Blog' started by chefwong, Dec 18, 2012.

  1. chefwong

    chefwong New Member

    Messages:
    710
    Location:
    District of Columbia
    9CC being the max, is the CC only the Hot or also the Neutral when taking this into equation.

    I've got 8-9 Hots of 12AWG, and a pair of #10 (G and N) going from a transfer switch back to a panel.
    AND Then, I just came across this derating issue...

    So to be complaint, it looks like instead of the 1" I was planning to run, I should run two 3/4 Back to the Panel and then split the lines from the transfer going back via 2 conduits.
    Last edited: Dec 19, 2012
  2. ActionDave

    ActionDave Electrician

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    Location:
    Colorado
    By pairs do you mean one hot and one neutral?
  3. chefwong

    chefwong New Member

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    710
    Location:
    District of Columbia
    Corrected my OP. The length of pipe between the transfer switch and panel is around 42" - 4 feet.
  4. hj

    hj Moderator & Master Plumber Staff Member

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    What makes you think ONE #10 neutral, the ground size is somewhat immaterial, will be sufficient for 8 or 9 #12 "hot" feeds, in the first place?
  5. cacher_chick

    cacher_chick Test, Don't Guess!

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    You must count all of the current carrying conductors.
  6. jwelectric

    jwelectric Electrical Contractor/Instructor

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    You would derate all conductor to 70% which would mean that you would need a #2 neutral

    Just what kind of generator are you connecting to your home?
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
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    Location:
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    quote; which would mean that you would need a #2 neutral

    Good luck twisting that under the terminal of a duplex receptacle.
  8. BobL43

    BobL43 DIY Senior Member

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    just clip off the excess strands:rolleyes: lol, NOT
  9. kenwalkerconst

    kenwalkerconst New Member

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    Location:
    Pinson, Al ( Birmingham )
    I'm not sure I'm understanding the question in the first place but the two line legs of 110V carry the current and have a canceling effect with the neutral carrying the imbalance. Think about you service entrance cable, TWO line legs with ONE neutral. Theoretically if you could balance both line legs you would not need the neutral. That what causes wierd things to happen when you "loose the neutral". Large 110V items on one leg like a refigerator comes on and light bulbs blow that are connected to the other leg. The refigerator drags down the voltage to say 50V on one line leg causing the other leg to see the imbalance of ( 220V less 50V = ) 170V.
  10. cacher_chick

    cacher_chick Test, Don't Guess!

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    Location:
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    He was asking about derating the conductors because they are being run in conduit.
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