Bonding of Steel building with Multiple Services

Merry Christmas


I am involved in a large steel building utilizing (3) 3000A Owner owned 13.800 to 480V transformer services. I had a question in reference to the G&B of the services. In article 250.58, and I have looked at what Mike has said in his books and also in his video of the 2017 code, that we need to use a common grounding electrode, yet also using a common ground could put neutral voltage on the steel building. So there are a few questions. First is which is correct? 2nd, if I run to the water pipe with one service, can I use building steel as a conductor to the other two services? There would be a bonding jumper at the building expansion joint. And all other grounding was pretty clear cut. I have tried to research this but do need some input. Thank you all for your time.


Senior Member
Northern illinois
Iirc, you can use bldg steel as a bonding conductor but not as a gec.

I am not sure you actually have three services. You may have three sets of service conductors.