Pull box rules

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S'mise

S'mise

Senior Member
Location
Michigan
I often wondered; why the calculations for a straight pull is 8 times and the calc for angle or u pulls is 6. Seems like it should be just the oposite. Pulling straight pulls seems like it would require less space as oposed to angle or u pulls. :-?

What are your thoughts on this?
 
Angle pulls fold more easily into the pull box than straight ones. You end up with a "camel hump" of wire in those straight pull boxes, and that can be a real bear getting the conductors bent down straight, without nicking the insulation.

I agree with the Code on this one.
 
S'mise said:
I often wondered; why the calculations for a straight pull is 8 times and the calc for angle or u pulls is 6. Seems like it should be just the oposite. Pulling straight pulls seems like it would require less space as oposed to angle or u pulls. :-?

What are your thoughts on this?
Click to expand...

It is assummed you may not pull straight through the box.
 
Thanks guys, makes sense. The "Camel hump" analogy explains it well. There are bends on both sides or the wire oposite the hump. (...But alas, my grasp of trig is poor)
 
kbsparky said:
Angle pulls fold more easily into the pull box than straight ones. You end up with a "camel hump" of wire in those straight pull boxes, and that can be a real bear getting the conductors bent down straight, without nicking the insulation.

I agree with the Code on this one.
Click to expand...

I agree with you on this one. :smile:
 
For larger conductors the 8X is IMO too conservative. When pulling 600 or 750 kcmil Cu conductors I would size the pull box larger than 8X. I've seen guys using 3" EMT with a 24" pencil box trying to pull 4-600 kcmil conductors. Very ugly. :rolleyes:
 
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