Transformer Supply Side Bonding Jumper

[jar546]

If you had a 480/277v to 208/120v wye-type transformer where the primary side of the transformer (xfmr) was fed from an MDP after the service, what table would you use to size the supply-side bonding jumper on the secondary side of the transformer if the xfmr was supplying power to a panelboard for an office?

Remember that the primary side feeding the transformer from the MDP would be sized per Table 250.122 as it is an equipment grounding conductor.

 

[Mr. Inspector]

table 250.102(C)(1)

 

[jar546]

table 250.102(C)(1)

I like that answer because it is correct.

 

[steveray]

Pics of said MBJ? Or MBJ vs. EGC.......? Helpful for the non-sparkys

 

[Mr. Inspector]

But I don't see any difference between table 250.102(C)(1) and table 250.66 Grounding Electrode Conductor for Alternating-Current System except in the notes.

 

[chris kennedy]

Yup
I always use T250.66 for the OP’s application because I have a tab on that page.

 

[jar546]

Yup
I always use T250.66 for the OP’s application because I have a tab on that page.

You are on fire today. Is it beer-thirty yet?