Another Garage Subpanel Q....

Discussion in 'Electrical and Wiring' started by Mach1, Aug 4, 2007.

  1. Aug 4, 2007 #1

    Mach1

    Mach1

    Mach1

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    About a year ago, I wired my attached garage with a subpanel. My sub in the garage is only 15 feet or so from the main. I used 4 AWG THHN 90C for both hots and netrual, 6 AWG bare stranded for the ground. The conductors are installed in 1.25" PVC 90C rated conduit.

    The table I looked at when I bought the wire said #4 was good for 95A (w/90C insulation) My breakers are the Cutler-Hammer BR type. Since there was no 95A breaker avaliable, I used a 100A.

    In hindsight, I'm wondering if using the 100 Amp BR this was the right thing to do? Should I switch it to a 90A breaker? The only reason I can think of to change it to 90A would be because of de-rating due to conduit fill. Can someone help me out?



    TIA,
    Mach1
     
  2. Aug 4, 2007 #2

    Parrothead

    Parrothead

    Parrothead

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    Derating isn't an issue here, since there are only three current-carrying conductors in the pipe. However, the wire you used is only rated for 95 amps, and they are protected by a 100- amp breaker. to make it legal, you're going to either have to up-size the wire to #3 or down-size the breaker to 90 amp.

    BTW, since this is a subpanel, did you make sure to remove the bonding jumper in the subpanel??? Just a thought.
     

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