Elecdesignguy
Member
- Location
- Lexington, KY. USA
Hello,
Back story on issue. I am working on a project where the 4/0 tinned bare copper GEC for a centrally located electrical room has been installed after all underslab conduit was installed but before the slab is to be poured. It has been laid on top of the vapor barrier and run approx 75' feet to the foundation wall where it was sleeved with PVC through the wall to the exterior ground ring of the facility. I had flagged this installation based on the 300-5 colunm 1 as requiring an installation of any cable or conductor to be installed in conduit as it is a conductor under a slab of a building. As it is installed right now there is only the thickness of the concrete slab over it. My understanding from school and mentors has always been that not only is installing the GEC in conduit when below a building slab, this is good practice because if anyone ever needed to cut or drill the slab for whatever and cut the unprotected GEC there could be a risk of accidental energzation of the structure or equipment in the event of a fault somewhere. As the old addage goes. Current will source every path to ground not just the easiest. I have found that my interprtation of 250-64 is that it deals with the standard for an exterior installation but can't I find this instance of under a building slab specifically addressed. No the CM is telling me I'm way off base in my observation. I need help here guys. I don't mind being incorrect, but where is it written.... Thanks!
Back story on issue. I am working on a project where the 4/0 tinned bare copper GEC for a centrally located electrical room has been installed after all underslab conduit was installed but before the slab is to be poured. It has been laid on top of the vapor barrier and run approx 75' feet to the foundation wall where it was sleeved with PVC through the wall to the exterior ground ring of the facility. I had flagged this installation based on the 300-5 colunm 1 as requiring an installation of any cable or conductor to be installed in conduit as it is a conductor under a slab of a building. As it is installed right now there is only the thickness of the concrete slab over it. My understanding from school and mentors has always been that not only is installing the GEC in conduit when below a building slab, this is good practice because if anyone ever needed to cut or drill the slab for whatever and cut the unprotected GEC there could be a risk of accidental energzation of the structure or equipment in the event of a fault somewhere. As the old addage goes. Current will source every path to ground not just the easiest. I have found that my interprtation of 250-64 is that it deals with the standard for an exterior installation but can't I find this instance of under a building slab specifically addressed. No the CM is telling me I'm way off base in my observation. I need help here guys. I don't mind being incorrect, but where is it written.... Thanks!