Pull Box Sizing

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finhead

Senior Member
A 3-inch conduit with six 4/0 AWG conductors enters the top of a pullbox, at which point the conductors separate into two groups of three and leave the bottom of the pullbox in two 2-inch conduits.What is the minimum vertical dimension of the pullbox?

A slightly different but related question is this. A 3-inch conduit with three 4/0 AWG conductors enters the top of a pull box and leaves the bottom of the pull box in a 2-inch conduit. What is the minimum vertical dimension of the pullbox?

Thanks,
Brian Dolan
 
jwelectric

jwelectric

Senior Member
Location
North Carolina
Re: Pull Box Sizing

314.28 Pull and Junction Boxes and Conduit Bodies.
(A) Minimum Size. For raceways containing conductors of 4 AWG or larger, and for cables containing conductors of 4 AWG or larger, the minimum dimensions of pull or junction boxes installed in a raceway or cable run shall comply with (A)(1) through (A)(3). Where an enclosure dimension is to be calculated based on the diameter of entering raceways, the diameter shall be the metric designator (trade size) expressed in the units of measurement employed.

(1) Straight Pulls. In straight pulls, the length of the box shall not be less than eight times the metric designator (trade size) of the largest raceway.

(2) Angle or U Pulls. Where splices or where angle or U pulls are made, the distance between each raceway entry inside the box and the opposite wall of the box shall not be less than six times the metric designator (trade size) of the largest raceway in a row. This distance shall be increased for additional entries by the amount of the sum of the diameters of all other raceway entries in the same row on the same wall of the box. Each row shall be calculated individually, and the single row that provides the maximum distance shall be used.

The distance between raceway entries enclosing the same conductor shall not be less than six times the metric designator (trade size) of the larger raceway.
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