georgepack1951
New member
I have a new Viscometer that has an intrinsically safe zener/shunt diode barrier between a transmitter and a field element. The transmitter is powered at 24VDC. A 4to20mA is from transmitter to DCS. My question is: In reading NEC 504-50 (B), for grounding in an intrinsically safe system it indicates that the diode requires an electrode that I assume would be connected to a ground rod and/or tripod, to maintain 1 Ohm resistance to ground. The entire ground assembly would then be connected to the local plant ground mat for ground potential. Is this what I need to do per NEC? In general I need to know the code interpretation(s) for grounding an intrinsically safe system in this case as it applies to NEC, articles 504 and 505. Do I need a grounding electrode per informational notes to 504-50? Please advise. Thanks.