transformer bonding question

[embryo3]

45KVA Primary and secondary OCPD

45KVA Primary and secondary OCPD

I have a 45kva 480v to 208/120v 3ø transformer that is suppliedby a 150amp existing breaker. The 45kva transformer in turn supplies asecondary is a 100amp disconnect that is within 10’ of the transformer

480vac3ø 45kva Primary OCPD (NEC 450.3(b) Primary OCPD at 250%. = 54amp x 2.50 =135amp
Next size up is 150amp breaker (NEC240.4(b).

PrimaryConductors: are 1/0 THHNconductors – (NEC 310.15 (b) = 1/0 awgrated for 150amp @ 75°c


Thesecondary OCPD is a 600vac 208vac3ø 100amp fused disconnect within10’ of the 45kva transformer.

Secondaryconductors are sized for 100amp disconnect= #2 THHN (NEC 310.15(b) #2 THHN rated for 115amp @75°c

Is this installation to code or am Imissing something?

 

[kwired]

I have a 45kva 480v to 208/120v 3ø transformer that is suppliedby a 150amp existing breaker. The 45kva transformer in turn supplies asecondary is a 100amp disconnect that is within 10’ of the transformer

480vac3ø 45kva Primary OCPD (NEC 450.3(b) Primary OCPD at 250%. = 54amp x 2.50 =135amp
Next size up is 150amp breaker (NEC240.4(b).

PrimaryConductors: are 1/0 THHNconductors – (NEC 310.15 (b) = 1/0 awgrated for 150amp @ 75°c


Thesecondary OCPD is a 600vac 208vac3ø 100amp fused disconnect within10’ of the 45kva transformer.

Secondaryconductors are sized for 100amp disconnect= #2 THHN (NEC 310.15(b) #2 THHN rated for 115amp @75°c

Is this installation to code or am Imissing something?

Read footnotes in 450.3(B) carefully. footnote 1 allows next higher standard overcurrent device, but the 250% primary situation only has footnote 3 attached to it. Otherwise looks like it is fine.