RNC used for grounding conductors

Status
Not open for further replies.
G

Glenn Becnel

Member
A contractor in our facility is using RNC for supporting the equipment grounding conductors. He is mixing schedule 40 & 80 in misc installations. I have been told only Schedule 80 can be used, per the NEC.

Please help with the location in the NEC with this practice.

Thanks in advance for the help.
 
I am aware of nothing in the NEC that prevents a person from mixing and matching wall thicknesses of PVC conduit. I can say, anecdotally, that you need to chamfer the inside edge of the sch 80 at couplings when changing to to sch 40. The fill tables for sch 80 are different (less) than sch 40. Schedule 80 might be required in sections if any of this pipe is run in areas that require protection from physical damage.

What I'm puzzled about is how you use PVC conduit to support EGC's. I can't picture what's going on. An overhead grounding grid in your facility?
 
Glenn Becnel said:
A contractor in our facility is using RNC for supporting the equipment grounding conductors.
Click to expand...
You mean the EGC's are inside or outside the conduit?
 
Pierre, you need to gamble as I do. I bet 50 cents that you're right, he's referring to GEC's.

See 250.64(B) for the requirements. Schedule 40 is all right as far as I know.
 
In my Masters class taken recently to bone up , the instructor told us that the code book never mentions sch. 40 - only 80
has anyone seen 40 mentioned ?
 
The instructor was close but not dead on. It is mentioned twice, see 517.30(C)(3)(2) and the tables for articles 352 & 353 in chapter 9.

Roger
 
I did not fully explain my question, sorry. It is in fact the GEC.
The contractor is installing Schedule 40 & 80 to support the GEC in the overhaed piperacks. These grounds are for 10' X 10' Instrument Analyzer Buildings raised on 12 ft steel pilings (this is in a Southeast Louisiana refinery). He is using no fittings for bends. He stops the conduit at 90's, etc and bends the wire. Then the conduit & GEC continue in another direction (no splices).
 
Although it does sound as though it is a sloppy installation, there is no danger involved.

Now, if there is a question of physical damage and the conduit is for protection, the installation might be in violation of 250.64(B).

Roger
 
Schedule 40 RNC may not be directly mentioned but it is nevertheless available and generally acceptable. The basic track is that RNC must be listed (352.6). UL does indeed list Schedule 40 RNC under Category DZYR. Any application limitations in the Category description are enforceable through 110.3(B). Some could potentially prohibit the GEC applications we believe the OP is actually describing, but there is no general prohibition.
 
The UL white book states that Sch 80 PVC shall be used for protection from physical damage is required. This information was added to the 2002 NEC.
Also the inside diameter of Sch 80 is smaller than Sch 40 so less wire fill is allowed, this was added to the 1996 NEC I think? making many pages longer.
 
Status
Not open for further replies.
Top