Service Ground

[ibo316]

for a 3-phase, 4-wire service, does a service ground conductor (other than the neutral grounded conductor) need to be supplied from a utility pad mounted transformer grounding electrode to the building service switchboard ground bar and electrode? I believe not but what if there is? Any problems with this? I'am not talking about High Impedance Grounding.

 

[A/A Fuel GTX]

I assume you are referring to a Grounding Electrode Conductor and the answer is no. I seriously doubt that the POCO would run a GEC from their xfmr to your service entrance equipment. You need to use all grounding electrodes that are available to your service entrance equipment at your building.

 

[iwire]

A GEC or EGC run between the supply transformer and the service gear serves no purpose and is in parallel to the grounded conductors.

This EGC or GEC could actually become overloaded with unbalanced neutral current under certain conditions