Concrete Encased PVC

[SpotOn]

Hi, I am working on a large single family dwelling and need to connect some of the Mechanical rooms with Rigid Non Metallic Conduit (PVC). Right now the walls are up and there is small (1" to 2") gravel as the floor. I was wondering what the standard practice is for running PVC inside and under a building. Do i need to lay sand around the conduit or is it ok to have it just on the gravel? they will be adding more gravel above the conduit and compacting the gravel prior to the pour.
Thanks in advanced.

 

[Ponchik]

The top of your conduit has to be at east 12" below finished grade if you have a 2" concrete above it, otherwise 18" below grade without vehicular street traffic.

Table 300.5 NEC 2008



If the floor is being finished with concrete then it is OK to have it on the ground for now until it gets covered by concrete.

 

[dicklaxt]

If you are contemplating a tough pulling situation make sure to use metalic elbows at the stub ups.I'd use them regardless as you don't know what may be needed in the future

dick

 

[Steviechia2]

The top of your conduit has to be at east 12" below finished grade if you have a 2" concrete above it, otherwise 18" below grade without vehicular street traffic.

Table 300.5 NEC 2008



If the floor is being finished with concrete then it is OK to have it on the ground for now until it gets covered by concrete.

If you are inside of the building there is no depth requirement. 0 inches

 

[SpotOn]

Thanks for the quick replies. This will be located inside the building not outside. Article 300.5 shows 0" of cover under a building (I assume that's what I'm to follow). I'm wondering if anyone uses sand to protect the pipe from the gravel, I saw the plumber did this and I figured he used sand for pitching his pipes but wasn't sure if it protects it as well . There are 3 90's and I over sized the pipe. The pull is only about 75' so it shouldn't be too bad.

 

[Steviechia2]

Thanks for the quick replies. This will be located inside the building not outside. Article 300.5 shows 0" of cover under a building (I assume that's what I'm to follow). I'm wondering if anyone uses sand to protect the pipe from the gravel, I saw the plumber did this and I figured he used sand for pitching his pipes but wasn't sure if it protects it as well . There are 3 90's and I over sized the pipe. The pull is only about 75' so it shouldn't be too bad.

code says no large rocks or sharp corners. I would use sand even though inside there won't be much movement like outside

 

[Ponchik]

If you are inside of the building there is no depth requirement. 0 inches

That is why i said.

"If the floor is being finished with concrete then it is OK to have it on the ground for now until it gets covered by concrete."

 

[kwired]

Thanks for the quick replies. This will be located inside the building not outside. Article 300.5 shows 0" of cover under a building (I assume that's what I'm to follow). I'm wondering if anyone uses sand to protect the pipe from the gravel, I saw the plumber did this and I figured he used sand for pitching his pipes but wasn't sure if it protects it as well . There are 3 90's and I over sized the pipe. The pull is only about 75' so it shouldn't be too bad.

code says no large rocks or sharp corners. I would use sand even though inside there won't be much movement like outside

The plumber has to be concerned with the slope of his drain lines otherwise they don't work correctly. Sand and gravel are easier to compact and be more certain there will be no future movement.

Large rocks or sharp corners is a judgemental call as far as how large or how sharp is acceptable. Size of raceway also comes into play.

Not only is zero cover allowed I think you could have your raceway embedded in the concrete floor if indoors, although it is probably a goood idea to have it at least covered with thin layer of sand, gravel, etc. so if concrete is ever removed it may survive that process.

 

[hillbilly1]

The biggest problem in installing conduits in the slab is the concrete workers stomping all over it and breaking it loose at the fittings. Use plumbers glue instead of conduit glue, it bonds a whole lot better and will not pull out as easy. If it is on top off the gravel, stake it down good so it doesn't float up in the concrete. Since your adding gravel on top of it, you should be ok. Using rigid steel 90's will not help the pull that much, but will resist being broken off above the slab.

 

[JP490440]

If it?s not too much hassle I would take a pick and scratch a shallow ditch for my pipe. It gets it ground level and keeps the concrete guys from breaking it with their rebar throwing around and generally trying to break your pipe.

I was working on a few projects and got back to a job after they had compacted a foot of crushed rock, terminex-ed and plasticed over everything. I ran my pipe on top of the plastic and had to fix multiple breaks under the rebar. Not fun