Free space within a box

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9275 said:
How do you calculate the required free space for conductors not in table 314.16(B)?
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Do you mean smaller than #18 or larger than #6? For larger than #6 there's no real free space calculation. The box is calculated according to the raceway size.
 
I have read 314.28 and I guess I'm not understanding.
314.28(A)(2) U pulls is what applies to what I'm trying to calculate can some one give me an example. Please & Thank You to everyone for replying.
 
Sure: Say you've got a 1.5" conduit entering the north side of the box, and the conductors leave through a 1.5" raceway on the north side of the box.

1.5" x 6 = 9"

You need a box 9" from north to south and wide enough to fit the pair of conduits from east to west for the box at this location.
 
George Stolz said:
Sure: Say you've got a 1.5" conduit entering the north side of the box, and the conductors leave through a 1.5" raceway on the north side of the box.

1.5" x 6 = 9"

You need a box 9" from north to south and wide enough to fit the pair of conduits from east to west for the box at this location.
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George, would your east-west dimension not have to meet:
"the distance between raceway entries enclosing the same conductor"
section of this rule ? 9" between + 1.5 + 1.5 =12" (plus allowance for locknuts, bushings, etc,)
 
Wait a sec - if there were a splice, then there would be a pair of conductors, so the math for east-west would be

1.5+1.5 = 3.0"

Also, I screwed up my original answer. There are two raceways. So north - south would be

(1.5" x 6) + 1.5" = 10.5"

So if there are splices, it would have to be a 12" x 4" box, if there are no splices, then it would have to be a 12" x 12" box, provided you can squeeze 9" in between the raceways.

Agreed?
 
I'm still not sure if I don't understand or if I'm not asking the right question.
I'm wanting to install four 1 1/4" raceways out of the top of a L 24"x W 4"x D 4" and one 2 1/2" out the center of the backside is this allowed. The 2 1/2" raceway has twelve #2's then be seperated evenly with three #2's in each 1 1/4" raceway.
Thank You all again for replying
 
Tables 314.16 A and B deal with standard sizes of boxes and commonly used wire sizes I tried to figure out how the volume allowances for 314.16 B were calculated but i had no luck if it were me
i'd post this question on the engineering calculations thread maybe you'll have better luck finding the answer you"re looking for there
 
See if this helps...

ry%3D480
 
9275 said:
I'm still not sure if I don't understand or if I'm not asking the right question.
I'm wanting to install four 1 1/4" raceways out of the top of a L 24"x W 4"x D 4" and one 2 1/2" out the center of the backside is this allowed. The 2 1/2" raceway has twelve #2's then be seperated evenly with three #2's in each 1 1/4" raceway.
Thank You all again for replying
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One step at a time.
The depth of your box is fine as 314.28 references us back to 312.6(A) in regard to the depth needed for the 2-1/2" with #2s coming in the back (opposite a removable cover)
314.28 also dictates the distance between conduits with the same conductors is
6X the conduit size. In this case it states the larger raceway so your 2-1/2 would have to be 15" from your 1-1/4".
The wall opposite the 1=1/4" would be 6X 1-1/4 = 7-1/2" + (3) x 1-14 but the requirement above would require that anyway.
 
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