PVC with Rigid 90's

[crispysonofa]

I saw a post on another forum the other day and had a few questions. The picture I linked shows sch40 PVC conduit run to a TA that is screwed into the rigid 90's which have a corrosion resistant tape on them. I like the idea of rigid 90's because you have less chance of damaging the 90 during the pull. Would you size your conduit based on PVC, Rigid or both? are the fill calculations the same for 90's as they are for straight runs? Thank you for the insight!

Pic:
https://i.redd.it/7zqm07znldjz.jpg

 

[jumper]

You would base it on the smallest dimension on any part of the conduit run.

In this case it would be the PVC conduit. Rigid/RMC has a greater internal area for the same trade size as PVC.

Elbows/90s of the same type of raceway, ie PVC or RMC, has the same area dimension as the raceway.

 

[crispysonofa]

Much appreciated. I think it's a great idea what say you?

 

[jumper]

Much appreciated. I think it's a great idea what say you?

Using RMC 90s with PVC?

Very good idea. Prevents raceway damage when pulling wire.

Note that the underground 90s need not be bonded when buried properly.

250.86
Exception No. 3: A metal elbow shall not be required to be
connected to the equipment grounding conductor where it
is installed in a run of nonmetallic raceway and is isolated
from possible contact by a minimum cover of 450 mm
(18 in.) to any part of the elbow or is encased in not less
than 50 mm (2 in.) of concrete.

 

[electrofelon]

Using RMC 90s with PVC?

Very good idea. Prevents raceway damage when pulling wire.
.

Hold on there. I just came off a job that had RMC 90's on EVERY conduit run 2" and over regardless of length, and on smaller runs over a certain length. It was a ridiculous waste of time and money. I have NEVER had an issue with pvc 90's on long pulls. I am not saying it is never a good idea, but imo definitely not a default thing to do. I would get more of a warm fuzzy feeling using higher than standard radius pvc 90's than standard radius RMC 90's.

 

[JFletcher]

I've never burned a 90 unless I was dumb enough (once) to not pull in a rope, instead using pull string to pull in heavy wire. Lots of Clear Glide or soapy water > RMC 90s.

eta: just looked at your pic - what type of building will that be when done? and those plastic conduit stackers are pretty neat. Is it job spec to have RMC 90s there?

 

[electrofelon]

Ok I know I was quite adamant in my previous response that RMC 90's are usually not necessary - and I still stand by that, but here is what happened on my job today. Subcontractor's scope, not my doing or problem, and it wouldn't have happened if I did it because I wouldnt have pulled it that way.....

 

[ActionDave]

Ok I know I was quite adamant in my previous response that RMC 90's are usually not necessary - and I still stand by that, but here is what happened on my job today. Subcontractor's scope, not my doing or problem, and it wouldn't have happened if I did it because I wouldnt have pulled it that way.....

That's pretty ugly. It looks more like a break through than a burn through.

 

[Fulthrotl]

Ok I know I was quite adamant in my previous response that RMC 90's are usually not necessary - and I still stand by that, but here is what happened on my job today. Subcontractor's scope, not my doing or problem, and it wouldn't have happened if I did it because I wouldnt have pulled it that way.....

appreciate you taking the time to post that.
been there, seen that before. i use pvc 90's
instead of GRC, but i also use mule tape,
and simpull.....