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Thread: Unit 10 Electrical exam Prep book 2014 cycle

  1. #1
    Join Date
    Sep 2017
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    Meridian Idaho. United states
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    Unit 10 Electrical exam Prep book 2014 cycle

    I have a question about The last example on page 299 or 300 of the 2014 Electrical exam preparation guide book.

    the question is: "What's the demand load for ten single-phase 12 KW 208V ranges on a three phase service."

    In step one, determine the maximum number of ranges between any two phases: 4

    How did they arrive at that?

  2. #2
    Join Date
    Dec 2012
    Location
    Placerville, CA, USA
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    18,176
    You have to assume that an attempt will be made to balance the load across all three phases.
    Each unit will get 208V from two legs of a 208Y/120 service.
    Equal distribution would be 3-1/3 ranges on each phase, so the closest we can get in real life will be four on one phase and three on each of the other two. The maximum number for any phase in the group will then be 4.
    You could put all ten on one phase, ignoring balance but that is not the interpretation of maximum number that the code is looking for.

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