Transformer GEC routed primary conduit

[hhsting]

I have transformer whose grounding electrode conductor is routed back inside primary phase and equipment grounding conductors in one conduit back to the main service grounding electrode system.

Does NEC 2014 any code section prevent or say anything for doing the above?

 

[tom baker]

Yes. 250.121 in the 2020 NEC says if you use the EGC as an GEC then it has to comply with the rules for a GEC, but this language is not in the 2014. However 250.62 (E) would still apply, requiring the GEC to be bonded at each end of the raceway. 250.121 was added to clarify what you are asking about...but if you don't bond the effectivness of the GEC is reduced by 97% (per the IEEE green book). Its a lot of extra bonding, often is easier to run GEC on outside of raceway and hit building metal. Please review 250.62 E.