?
Tuesday, November 25, 2014
Question:
Hi Charlie,
I recently installed a 24' x 26' steel building and brought in a 100 amp service via underground pvc conduit to a sub panel. My question is what is the proper way of grounding the system and building and what type of conduit is required for interior and exterior branch circuits.
Thanks, George
A
Answer:
Hey George thanks for your questions. I suspect that it is actually a feeder because you use the term "sub panel". If so then 250.32(A) requires a grounding electrode system be installed using all the electrodes described in 250.52(A)(1) through (A)(7) that are present. If none of those exist then one or more of the ones in 250.52(A)(4) through (A)(8) must be installed and used. The equipment grounding conductor must be connected to the electrode(s) at the building and the grounded neutral conductor must not be connected to the EGC or the electrode(s) as stated in 250.32(B)(1). You didn't mention what the building is being used for but in general you can use any of the wiring methods in Chapter 3 by following the rules in the .10 [Uses Permitted] and 12 [Uses Not Permitted] sections.