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Thread: Pull and Junction Box Sizing

  1. #1
    Join Date
    Mar 2003
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    New York
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    Pull and Junction Box Sizing

    314.28 gives requirement for the LxW dimensions for Pull / Juction Boxes.

    Are there requirements for minimum volume ?

    314.16 does address this but only up to #6 conductors.

    Am I missing something?

  2. #2
    Join Date
    Feb 2003
    Location
    Florida
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    Re: Pull and Junction Box Sizing

    As long as you meet the requirements specified in 314.28, volume calculations do not need to be made. This is figured into the respective formulas.

    Table 314.16(A) does not go above #6 because you wouldn't be able to put anything larger than #6 in the particular boxes listed. If you are installing larger than #6 conductors, you will have to perform a box fill calcualtion and select a box with the minimum volume allowance.
    Bryan P. Holland, MCP

  3. #3
    Join Date
    Mar 2003
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    New York
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    Re: Pull and Junction Box Sizing

    bph...

    Thanks for the reply, but I guess that is what I am asking ... how to perform box fill calculations for conductors over #6, say 250's.

    Thanks again for the help.

  4. #4
    Join Date
    May 2003
    Location
    Salt Lake City, Utah
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    Re: Pull and Junction Box Sizing

    I would think that bending radius would become an issue before box fill would when dealing with 250's.
    Ryan Jackson, Salt Lake City
    Inspector, Instructor

  5. #5
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    Feb 2003
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    Re: Pull and Junction Box Sizing

    Box fill calculations are really designed for boxes that are intended to be used as an outlet where a device or fixture will be mounted.

    There are simply not many applications that would require larger than #6 branch-circuits that terminate into a box.

    Above #6 are generally feeders and service conductors that may require pull boxes, j-boxes, and conduit bodies, but will terminate in large enclosures like panelboards and cabinets.

    However, you may be able to determine a ratio using 314.16 to determine larger sized conductors. I have never run into this problem or had a need to do so.
    Bryan P. Holland, MCP

  6. #6
    Join Date
    Jul 2003
    Posts
    1

    Re: Pull and Junction Box Sizing

    The Box Dimesionning is what you have to consider, allowing at all time the space for the bending radius of the conductor, The rule says that for straight pull Box Size should be At least 8 Times the Conduit Size, for Perpendicular Pull The Diagonal Dimension fron Conduit Center To Conduit Center is 6.5 Times Conduit Size, The Depth Of The Box Should Be Twice the size the largest conduit entering the box. Conduit Spacing One Conduit Size OC.

  7. #7
    Join Date
    Mar 2003
    Location
    New York
    Posts
    29

    Re: Pull and Junction Box Sizing

    Thanks to all !

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