John- We are under the '05 NEC. I suspect that you were looking at the '08 which would require a grounding conductor.
Ernie- The issue here has many facets that I found challenging and I know this is something that you deal with routinely.
First the conductors are unfused at the xformer secondary located outside and run to a transfer switch inside the building. Do we have words in the code that say we need a bonding conductor when running RNMC for this type of installation?
Secondly if the conductors are fused do we need a EGC or a bond wire? In the case of the EGC it is selected per 250 122 and we need a full size EGC in each raceway. If we only use a bond conductor we size it based on 250.66 and that size is related to the conductors in each raceway. Hence a considerable size difference.
I still can't find where we need a bond or a ground for this type of installation in the '05 unless the system has GFPE.
Last question - Under the '08, we need a EGC, so would we also need a bonding conductor?
Last edited by George Little; 12/23/08 06:39 PM.
