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Calculation for feeder or service neutral

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    Calculation for feeder or service neutral

    In my attached picture how is 5100VA calculated for the lighting and small appliance load when general lighting and the small appliance loads are calculated at 4500VA and 3000VA for the minimum feeder size on this dwelling? Why is it not 7500 for them together?

    you can reference my picture or page 791 of the 2017 NEC.
    Attached Files

    #2
    The General lighting load is 4,500VA
    Small Appliance Branch Circuit is 3,000VA
    Laundry is 1,500 VA
    Total = 9,000VA

    now apply the demand factor from 220.42

    The first 3,000VA at 100%; so 9,000VA - 3,000VA = 6,000VA
    then we calculate the remainder at 35%; so 6,000 x 0.35 = 2,100VA

    Add the 2,100 VA and add it back in to the first 3,000VA we are required to include at 100%.

    2,100VA + 3,000VA = 5,100VA

    Hope that helps
    Kevin

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      #3
      Thank you Kevin now I think I understand. What confused me is table 220.42 is titled lighting load demand factors but section 220.52 A & B for small appliance and laundry direct you to apply the demand factors in table 220.42.

      Thank you!

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