transformer grounding

[theshockdoc]

I'm working on understanding grounding electrode conductor vs. eguipment grounding conductors.
If I were to have a 75 kva dry type transformer
fed underground with pvc. I would

1. Run a eguipment grounding conductor with the primary based on 250.122 OCPD. Connected to transformer case.
2. Run a grounding electrode conductor to the Xo
based on 250.66 secondary conductor size. Connected to Xo and grounding electrode system or
seperate grounding electrode?
IE. Building steel or seperate ufer?
3. Run a bonding jumper based on 250.66 secondary conductors. Connected to Xo and transformer case.
4. Run a equipment grounding conductor with the secondary based on?

Everytime I think I got it down someone will ask me to explain and I get a little mixed up.
Need a little help.

 

[Ed MacLaren]

Re: transformer grounding

I would suggest the grounding/bonding connections illustrated below.

I will leave it to someone familiar with the NEC, to supply code references.

Ed

[ September 24, 2004, 12:05 PM: Message edited by: Ed MacLaren ]