Bends

A

Alwayslearningelec

Senior Member
Location
NJ
Occupation
Estimator
Seeing many jobs not have notes that they want pulll box every 270 degree and not 360. Guess this makes pulling easier. Any reason from an installation why you would want to put box every 360 and not 270?
 
Depends on we’re bends are and the degree- would rather pull through 4-90 36” sweep then 3-90 12” sweep- plus if the bends are close to each other or spaced—-
There is pulling calculations that’s what you should rely on

That rules is like the NEC trying to fix something that installer knows better
 
Alwayslearningelec said:
Seeing many jobs not have notes that they want pulll box every 270 degree and not 360. Guess this makes pulling easier. Any reason from an installation why you would want to put box every 360 and not 270?
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I always want as few pull points at possible..every pull point adds labor and the additional handling of the conductors at any pull point increases the chance for conductor insulation damage.

Using a pulling calculator, I would even be willing to go beyond 360° if the code would permit that.

Often those calculations will show you can go well beyond 360° without conductor damage either from the pulling tension or the sidewall pressure. Sidewall pressure is the crushing force on the insulation as the conductors are pulled around bends and is a function of the pulling tension and the radius of the bend. In the calculations I have done, the sidewall pressure and not the pulling tension has always been the limiting factor. I have used 3" radius bends on a 2" conduit pull, to avoid additional pull points
 
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