rigid 90 or pvc

[darrylcooper]

Question, When bringing up pvc from under ground that will go through concrete, I have seen the 90 be Pvc and I have seen it be change over to rigid. What is the different is this a AHJ thing or spec. thing. I have done them both way for different contractors I have work for. is this A code thing? if so where is it located.

 

[mdshunk]

Re: rigid 90 or pvc

That's mostly a design issue. Sometimes I'll use a RMC factory 90 in a buried run of PVC if I expect a hard pull. Some people will stub up their PVC with RMC 90's and stubs in locations where severe physical damage is expected. This brings up a 250.132 issue that sometimes has an aestetically ugly solution.

 

[jbwhite]

Re: rigid 90 or pvc

300.5 and 300.50 (B) in 2005 have cases where rigid is required.

 

[benaround]

Re: rigid 90 or pvc

darryl,

On a hard pull the rope will burn right thru a pvc 90 and let me tell you,it's not fun.
On the feed side of a wire pull a pvc 90 is ok,but on the pull side a RMC 90 is good insurance.

 

[mc5w]

Re: rigid 90 or pvc

I have found that it actually PAYS to use oversize PVC pipe for underground wiring. The last time that I replaced an underground 200 amp service was during the 2nd quarter of 2002 and what I used was 2.5 inch schedule 80 PVC conduit. One issue was that the pipe would be right in a prime area for planting trees and in fact the old direct burial cable had been broken by the Tree Root Circuit Breaker Method.

Another issue was that I had to go around the existing driveway with the result that I had 720 degrees of bends including the 2 90s at the bottom of the pull box in the middle. I also did not have a place to hook up a forklift truck or wire pulling winch. The 4/0 aluminum URD cable went right into the 2.5 inch PVC conduit and was about the easiest 200 wire that buddies and I have done in a long time.