Elbows

[Alwayslearningelec]

How does one determine if a sweep elbow would be needed as opposed to a standard elbow when running underground work? This would be in the estimating phase. Thanks

 

[Seven-Delta-FortyOne]

-Specs. In my area, we install the underground for PG&E for a service, they pull the conductors. They spec sweeps.

-Experience. “I not tryna pull 6x350’s through a short elbow with one helper”.

-Depth. If you’re installing pvc under a 4” slab and you’re going to bury it 6” deep, the 36” sweep is gonna look funny.

-Calcs. I have no experience with this, but there are calculations, probably an app, that will give coefficient of friction numbers, pulling force required, probability of jamming, etc., for different pulls.

 

[don_resqcapt19]

Typically the specifications, but also may be required based on the pulling calculations if they revel that a standard radius elbow results in too much sidewall pressure.

 

[infinity]

How does one determine if a sweep elbow would be needed as opposed to a standard elbow when running underground work? This would be in the estimating phase. Thanks

Unless the spec calls for sweeps I would assume that standard elbows will be used.

 

[Alwayslearningelec]

Thank you.

 

[kwired]

They are all sweeps, unless you install a plumbing style elbow. The only so called elbows where you can make such a sharp turn are generally something with a cover like a conduit body. Though there are short 90's out there and I've used some on occasion but really not seeing where NEC would allow them. They are handy sometimes but definitely not when there is a longer pull being made through them.

The "standard elbow" happens to be at/near code minimum bend radius for a particular raceway/size. There is often more than one option for bend radius for "non standard" pre made elbows.

 

[electrofelon]

Depends on the run. Sometimes I will voluntarily use larger radius bends, makes pulling easier.