SDS GEC to water pipe

[james blake]

A co-worker and I were wiring a 150 KVA transformer with a 480V primary and a 208Y120V secondary, in the basement of a school. We were feeding a 400A panel. Our secondary ungrounded conductors were two parallel runs of 4/0 cu THHN. I told my co-worker I would pick up the 1/0 cu THHN (based on the largest ungrounded conductor) to run to our water pipe electrode. He told me that there is no way he is going to run 1/0 when we only need to run a 6 awg to the water pipe. He referenced 266.66(A). I explained to him that 250.66(A) applied to ground rods and driven pipe electrodes, not water pipe. He would have none of that. He said he had been doing it like that for years and that even an inspector said he was right. I've been working in the electrical trade for eleven years, and my co-worker has been in it for at least twenty or more. Does he know something I don't?

 

[mcclary's electrical]

You are correct.

 

[james blake]

Thank you for your reply. I am kind of standing by myself on this because my other co-workers are sort of dicey on this kind of stuff.

 

[augie47]

Welcome to the Forum.
The two things you have done that apparently others have not is to question and come her for opinions.
I believe you will find both traits to be helpful.
I had a supervisor of inspectors make a similar argument about a #6 being all that's needed to a water line regardless of the service. Art 250 is confusing to all of us.

 

[james blake]

Thank you for the welcome. I came here because I really have no one else to back up the facts I brought up to my co-worker from the NEC. I'm not out to prove any body wrong, but just because a person has been "doing this for years" or that an inspector passed his previous jobs doesn't make it right.

 

[mcclary's electrical]

Thank you for the welcome. I came here because I really have no one else to back up the facts I brought up to my co-worker from the NEC. I'm not out to prove any body wrong, but just because a person has been "doing this for years" or that an inspector passed his previous jobs doesn't make it right.

You summed it up well with this post. Just because it has worked in the past doesn't make it correct. The reasoning for the #6 is the rods will never flow more current than the #6 can handle, He cannot say the same for a water line.

 

[james blake]

Thanks for your input on this issue guys!!!

 

[james blake]

I would also like to make a correction to my first post. When I typed "He referenced 266.66(A)" I of course meant 250.66(A). You guys obviously new what I was talking about.