Message from reader:
I am reviewing a reseach laboratory design for an owner in which Schedule 80 PVC conduit, and up to 4/0 AWG welding cables are being specified for feeders and branch circuits to maintain power quality.
The "clean power" source is a 180 kVA rotary UPS on the sixth floor of a lab building serving sensitive equipment on the 4th, and 5th floors. The lab professor is requesting the PVC conduit and welding cabling stating that these wiring methods are European standard and required for maximum power quality in his lab.
I question the wiring methods.
To refute the PVC conduit, I can refer to the IEEE Emerald Book, Chapter 9, "Recommended Materials".
I am unable to locate any Code limitation or other authority that prohibits, or even
discourages welding cable as a grounding conductor.
Can someone offer me any advice?
Jeffrey M. Leavenworth, P.E.
Joe Tedesco, NEC Consultant