transformer to building steel

[emahler]

how do i size the bond from secondary transformer to building steel? for example, 75kVa 480 primary to 208 secondary...75A input at 480V, 150A load at 208V...

table 250.66 or table 250.122? and size per the line or the load?

thanks..

 

[don_resqcapt19]

Take a look at 250.30(A)(3).

 

[M. D.]

you may find this helpful ,..
http://ecmweb.com/nec/electric_grounding_bonding_separately/

 

[emahler]

ok...i asked using the incorrect terms, i apologize...

250.30(A)(7) is what covers it...it's actually the grounding conductor size that i need...

but that is sized according to 250.66

in this installation, we have 2 transformers, one feeds a 150A panel with a set of 1/0...which I can use a #6 from the transformer to the steel...correct?

the 2nd feeds a 200A panel with a set of 3/0...which would require a #4 from the transformer to the steel...correct?

am i reading this correctly?

 

[M. D.]

http://www.electrician2.com/calculators/t250_66.html

 

[emahler]

http://www.electrician2.com/calculators/t250_66.html

oh, a wise guy heh?