Pull box sizing

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augie47

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Tennessee
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State Electrical Inspector (Retired)
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

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Chapel Hill, NC
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Retired Electrical Contractor
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
ry%3D400
 

infinity

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New Jersey
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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
ry%3D400

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

Ponchik

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CA
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Electronologist
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

Senior Member
Location
CA
Occupation
Electronologist
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

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Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
"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
 
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