Pull box sizing

[Ponchik]

Please see the file and tell me if I did the pull box sizing correctly or where I messed up.

https://www.dropbox.com/s/u5rmwdmpx0qzk53/New Doc 33.pdf?dl=0

Thank you

 

[augie47]

As I read it, 314.28 for U pulls requires the "opposite" wall to be 6 X PLUS the sum of the others so "A" would be 43" assuming the conduits are all in the same row.
As far as the "B" dimension, your calculations follow the Code as you have your 6X between entries, however, physically you would need to add the diameter of the 5" conduit as you started from the inside edge and you would need to allow for lcoknut/bushing dimensions as you simply add the conduit diameters.
If your box depth allows the conduits to be in different rows the numbers would change.

 

[Dennis Alwon]

Here is a good graphic

Looks like you got it correct. Unfortunately 43 will not work for "B" since you cannot maintain 30" between the 5" pipe and the next and still have space between each conduit. However I think the calculation is correct

 

[infinity]

Here is a good graphic

Looks like you got it correct. Unfortunately 43 will not work for "B" since you cannot maintain 30" between the 5" pipe and the next and still have space between each conduit. However I think the calculation is correct

If these conductors were being spliced in this box would you still need to meet the "C" dimensional distance?

 

[Dennis Alwon]

If these conductors were being spliced in this box would you still need to meet the "C" dimensional distance?

Good question but since the nec does not give an exception to that I would say you still have to use the dimensions as stated

 

[Ponchik]

Here is a good graphic

Looks like you got it correct. Unfortunately 43 will not work for "B" since you cannot maintain 30" between the 5" pipe and the next and still have space between each conduit. However I think the calculation is correct

So my "A" dimension will be minimum 43" and the "B" dimension (in theory) will be 48", but in reality with the lock nuts around 55"?

 

[Ponchik]

Good question but since the nec does not give an exception to that I would say you still have to use the dimensions as stated

"the distance between raceway entries enclosing the same conductor shall not be less than 6 times the trade size of the larger raceway"

I don't think the splice box needs the distance between the conduit, because when the cable is spliced it is not the "Same Conductor" any more. The distance between the conduit must be maintained if it is being used as a pull box with the same conductor coming in and going out.

 

[Dennis Alwon]

"the distance between raceway entries enclosing the same conductor shall not be less than 6 times the trade size of the larger raceway"

I don't think the splice box needs the distance between the conduit, because when the cable is spliced it is not the "Same Conductor" any more. The distance between the conduit must be maintained if it is being used as a pull box with the same conductor coming in and going out.

Then how would you size the box with a splice

 

[Ponchik]

Then how would you size the box with a splice

View attachment 13803

The distance between the right conduit entry and between the lower conduit entry does not have to be 18" because the box is being used a splice box.

 

[Dennis Alwon]

Thanks-- I learned something again. It makes total sense but I didn't think there was an exception for that.