Use of underground conduit - standards
Use of underground conduit - standards
(OP)
Hello,
I have been working on a project which requires PVC coated rigid conduit for all underground wiring. In the past I have used PVC conduit encased in concrete, with steel risers. I was told that PVC was not desirable because in very cold temperatures, the ground will shift and the PVC will break. The frost line is about 5' down and the PVC is installed at 36".
I have been contacting PVC manufacturers in order to discuss this possible problem. No one I have contacted seems to know anything about this. Does anyone in this forum have any experience or literature which would justify the use of PVC coated rigid underground?
thanks,
EE
I have been working on a project which requires PVC coated rigid conduit for all underground wiring. In the past I have used PVC conduit encased in concrete, with steel risers. I was told that PVC was not desirable because in very cold temperatures, the ground will shift and the PVC will break. The frost line is about 5' down and the PVC is installed at 36".
I have been contacting PVC manufacturers in order to discuss this possible problem. No one I have contacted seems to know anything about this. Does anyone in this forum have any experience or literature which would justify the use of PVC coated rigid underground?
thanks,
EE





RE: Use of underground conduit - standards
The worst corrosion occurs at the earth-air boundary. We specify PVC-coated steel for risers. If the steel conduit is going to be concrete-encased, the soil corrosion issue is obviously not as big an issue.
The steel conduit provides additional physical protection and EMI shielding compared to rigid PVC.
If the owner has specified it and is willing to pay for it, I don't see an issue. For UG conduit, I don't think the cost is justified, but there are no technical issues that I am aware of.
RE: Use of underground conduit - standards
RE: Use of underground conduit - standards
Sched 80 PVC is another option, but you lose a lot of fill area compared to Sched 40.