Hello, I'm looking for a bit of clarification on motor control circuit grounding as I'm getting conflicting answers from peers. First the scenario:
An electrical room with 480V MCC and interposing relay panel(IRP), each piece of equipment has an equipment grounding conductor connected to the ground ring in the room. There's a grounded cable tray connecting the MCC and the IRP. The MCC bucket contains an 80VA, 480:120 CPT.
If someone were to run a 4/C cable, without a ground, for the 120V start/stop signals between the MCC and the IRP via the cable tray would that be an NEC compliant installation?
I've read 250.110 and 250.112 and this thread: https://forums.mikeholt.com/showthread.php?t=177826 and it still isn't clear to me where the code requires this control circuit to carry a grounding conductor if both pieces of equipment are already grounded.
An electrical room with 480V MCC and interposing relay panel(IRP), each piece of equipment has an equipment grounding conductor connected to the ground ring in the room. There's a grounded cable tray connecting the MCC and the IRP. The MCC bucket contains an 80VA, 480:120 CPT.
If someone were to run a 4/C cable, without a ground, for the 120V start/stop signals between the MCC and the IRP via the cable tray would that be an NEC compliant installation?
I've read 250.110 and 250.112 and this thread: https://forums.mikeholt.com/showthread.php?t=177826 and it still isn't clear to me where the code requires this control circuit to carry a grounding conductor if both pieces of equipment are already grounded.
