Pull boxes

[TyDodge]

My question is this...There is much information out there explaining how to figure out two dimensions of a pull box. I understand how to figure those two given raceway sizes. Where does it tell us how to figure the third, depth or width in the case of rear entry???? I see nothing in the NEC or don't remember that being addressed in any of the books or videos I've studied.

 

[jumper]

It is still just an angle or a U pull and you can calculate it that way or in this case you can use the exception.

314.28 Pull and Junction Boxes and Conduit Bodies.
Boxes and conduit bodies used as pull or junction boxes
shall comply with 314.28(A) through (E).

(2) Angle or U Pulls, or Splices. Where splices or where
angle or U pulls are made, the distance between each raceway
entry inside the box or conduit body and the opposite
wall of the box or conduit body 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.

Exception: Where a raceway or cable entry is in the wall
of a box or conduit body opposite a removable cover, the
distance from that wall to the cover shall be permitted to
comply with the distance required for one wire per terminal
in Table 312.6(A).

 

[TyDodge]

What I have is four 4" RMC coming in through the rear and four 4" RMC exiting through the bottom. Each conduit contains 3-500 kcmil and 1-1/0 conductors. By my calculation the pull box has to be 36" high and it can be as shallow as 6" because of the exception in 314.28(a)(2). The conduits carrying the same conductors have to be at least 24" apart. My question is this. How wide does this box have to be??? I know that in order to get four 4" conduits into it that it definitely has to be at least say 18-20 inches just to get locknuts on but is there anywhere in the code that states that it needs to be wider? As far as I can see there would be no calculation from left to right, right to left or top to bottom. Just bottom to top (6x4)+4+4+4 and rear to front (6x4)+4+4+4. The rear to front is waived due to the exception. Again every box has three dimensions and with entries in only two I think the code only has requirements for those two. Correct?

 

[Ponchik]

If I am picturing this correctly the size of the box will be minimum (4x6"=24 plus lock nuts = 30" tall) (4"x4 = 16 plus lock nuts = 20" wide) and 6" deep based on 312.6(a) column #1 (one wire per terminal)