Transformer Secondary tap Question

[PowerdT]

Say I have 112.5KVA xfmr. 4160 primary with 208Y secondary. This xfmr feeds two panels 150A each. Each panel has main disconnect. My question Is the secondary OCPD required? is the secondary OCPD usually installed next to a meter? And in one line diagram, How can you show feeder tap diagram?

Correct me please if I size the OCPD wrong for the above xfmr. The primary FLA is 15.6A and the secondary FLA is 312.2A. The primary OCPD 15.6*300% is 46.8. Next size up 50A fuse Per 450.3A. The secondary OCPD 312.2*125% is 390.25A next size rule 400A per 450.3B.

 

[electrofelon]

Say I have 112.5KVA xfmr. 4160 primary with 208Y secondary. This xfmr feeds two panels 150A each. Each panel has main disconnect. My question Is the secondary OCPD required? And in one line diagram, How can you show feeder tap diagram?

Correct me please if I size the OCPD wrong for the above xfmr. The primary FLA is 15.6A and the secondary FLA is 312.2A. The primary OCPD 15.6*300% is 46.8. Next size up 50A fuse Per 450.3A. The secondary OCPD 312.2*125% is 390.25A next size rule 400A per 450.3B.

Looks ok to me. I am making assumptions just following your numbers as to what row in 450.3(a) applies since you didnt give complete details. Yes secondary protection is required per the table

is the secondary OCPD usually installed next to a meter?

Usually not because, unless this is a utility transformer in which case none of this applies, you wouldnt usually need a meter.

 

[PowerdT]

Looks ok to me. I am making assumptions just following your numbers as to what row in 450.3(a) applies since you didnt give complete details. Yes secondary protection is required per the table



Usually not because, unless this is a utility transformer in which case none of this applies, you wouldnt usually need a meter.

I am sorry. Yes assuming any location not more than 6%Z per 450.3A.

It is utility transformer, so does that mean I sized it wrong?