HDPE

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mcelweec@gmail.com

CMAC1
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Electrician
I have a project involving 20 x 200ft 4" conduits with 4x600mcm in each. The utility ( coned) does not allow PVC but will allow HDPE , I've never worked with this before so was wondering is there any issues I need to be concerned about. At each end I will be turning up with GRC 90's. These are being installed underneath the building slab.
 
mcelweec@gmail.com said:
I have a project involving 20 x 200ft 4" conduits with 4x600mcm in each. The utility ( coned) does not allow PVC but will allow HDPE , I've never worked with this before so was wondering is there any issues I need to be concerned about. At each end I will be turning up with GRC 90's. These are being installed underneath the building slab.
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The fittings for HDPE and RPVC are not interchangeable. They do make a 4" HDPE to IMC/RMC fitting; here's one of them (first one, the "E-Loc", EL 4.500):

http://www.carlonsales.com/couplings.php

If your HDPE is oval shaped on the end, a large C-clamp applied ~ 6-8" from the end will draw it circular again enough to get the coupling on there.

You'll need to dig a fairly large trench at both ends for guys to work in to install your 90* GRC/RMC elbows; the HDPE conduit probably has some upward angle to it, especially when it's line-bored in (with 20 conduits I assume you have an open trench). It needs to be flat/level. It's very stiff and very springy, and after you make the connections, you'll probably want a sizeable amount of concrete over it to keep it from lifting out of the ground when you pull wire - I wouldn't rely solely on the clamps holding the RMC to the wall/strut nor the backfill weight to keep it down.

eta: here are two threads that are relevant to the topic:

http://forums.mikeholt.com/showthread.php?t=180582

http://forums.mikeholt.com/showthread.php?t=181918
 
When PVC burns it give off toxic fumes.
Coned sent out a notification to all contractors advising them of this, when I asked for alternatives the rep suggested HDPE or FRE.
 
mcelweec@gmail.com said:
When PVC burns it give off toxic fumes.
Coned sent out a notification to all contractors advising them of this, when I asked for alternatives the rep suggested HDPE or FRE.
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That's just outright stupid. How is PVC going to burn underground?

Even if it does manage to char from excess heat, it's not just underground but it is usually outside.

That said, they are the POCO and they have little if no oversight.
 
Smart $ said:
That's just outright stupid. How is PVC going to burn underground?

Even if it does manage to char from excess heat, it's not just underground but it is usually outside.

That said, they are the POCO and they have little if no oversight.
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Kind of my thoughts.

We have some instances with some POCO here where we bury raceway and POCO pulls conductor through it. It is generally ahead of their metering and never enters any buildings either. I would think anything that enters a building would ordinarily not be on their side of the service point and they wouldn't have much say over how it gets installed either.
 
mcelweec@gmail.com said:
I have a project involving 20 x 200ft 4" conduits with 4x600mcm in each. The utility ( coned) does not allow PVC but will allow HDPE , I've never worked with this before so was wondering is there any issues I need to be concerned about. At each end I will be turning up with GRC 90's. These are being installed underneath the building slab.
Click to expand...

We use Duraline HDPE on a fairly regular basis here lately. You can only get 4" in sch. 80 on a reel, due to sch. 40 flattening into an oval if it's on a reel. If you want 4" sch. 40 HDPE, it comes in sticks 20 or 40 feet long, I believe. The couplings at the 4" size are pretty expensive. Off the top of my head, I bet they're at least $35 apiece.

We use Shur Lock II couplers from Duraline, if you're looking for a UL listed coupling, maybe it doesn't matter since it's power company conduit?

The power company on our last project used 4" HDPE on reels for all their underground primary runs to their sector boxes. The power company engineer thought it'd be easier than a bunch of glue joints every 20' with pvc. I know their field guys were having a hell of a time with the HDPE conduit curling at the ends where they were trying to transition to a 90 out of the ground. They were pretty grumpy when I talked to them and said they wished their engineer would've just let them use pvc instead, even with all the extra time spent gluing.
 
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