I have another one of those questions, that I might have seen here, but I can't remember if I did.?!
In medical offices sec. 517.13 requires effective grounding path for patient areas.
The question would be a dental chair. 1) Is redundant grounding required? 2) If the chair is fed from under the floor and it is PVC pipe, would you need 2 ground wires to have a double ground?