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Thread: Looking to find illumination density requirements in NEC

  1. #1
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    Looking to find illumination density requirements in NEC

    Hi all, I'm trying to find watts/sq foot for residences, hospitals, office bldgs in NEC.

    Any clues would be helpful.

    Thx,

    "Humble Hank"

  2. #2
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    Recognize that the NEC will not be saying much, if anything, about lighting levels themselves.
    But it will tell you how to estimate lighting load for feeder and service calculations.
    See Table 220-3(a) for square footage factor for non-dwelling areas of different types.
    Once you get that total, you can reduce the total by a demand factor, except for hospitals and other uses where the full load is planned to be on all the time.

    OOPS. Out of date section number. See post below.

  3. #3
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    Section 220.12 and T220.12 for minimum load calculations of watts(power) required per square ft for various occupancies.
    "Electricity is really just organized lightning." George Carlin


    Derek

  4. #4
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    reply

    Thx sir! It's referenced in my test prep materials which are full of code references to old code!
    The firm I m working with must be citing 2005/2008 code and I believe I'm to be tested on 2011 code.
    My book is 2011. Thank you!

  5. #5
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    SWEET! Those are the droids I'm looking for!

    SWEET! Those are the droids I'm looking for!

    Quote Originally Posted by jumper View Post
    Section 220.12 and T220.12 for minimum load calculations of watts(power) required per square ft for various occupancies.

  6. #6
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    Quote Originally Posted by docj67 View Post
    SWEET! Those are the droids I'm looking for!
    Demand factors are T220.42.

    My answers are based on the 2014, but I am pretty sure the 2011 was the same.
    "Electricity is really just organized lightning." George Carlin


    Derek

  7. #7
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    Note, however, that there are also other types of lighting (such as show window) that are explicitly not included in this calculation.

    And energy laws in various states (especially CA) will specify maximum wattage for a lot of applications, which may be lower.

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