Secondary protection or not?

[chevyx92]

Scenario: A 150KVA XFMR fed with 3phase 480V stepping down to 120/208V. Xfmr secondary feeds a 400Amp MLO panelboard. Need OCP or not? All the breakers in the panelboard are 100A or greater so its not a lighting and appliance panelboard. By code do I need a fused disconnect on the secondary? I am getting confused now!

 

[aftershock]

Do you exceed 6 throws?

 

[mistermudd]

Maybe? Depends on the on which scenario your installation falls under. 240.21(C) 2,3,4,5 or 6

 

[acrwc10]

Scenario: A 150KVA XFMR fed with 3phase 480V stepping down to 120/208V. Xfmr secondary feeds a 400Amp MLO panelboard. Need OCP or not? All the breakers in the panelboard are 100A or greater so its not a lighting and appliance panelboard. By code do I need a fused disconnect on the secondary? I am getting confused now!

240.4 (F) may be of interest to you. It answers your question "I think" :smile:

 

[benaround]

240.4 (F) may be of interest to you. It answers your question "I think" :smile:

I agree with you!!

 

[Pierre C Belarge]

408.36(B) Supplied Through a Transformer.
Where a panelboard is supplied through a transformer, the overcurrent protection required by 408.36 shall be located on the secondary side of the transformer.

[there is an exception, it is very restrictive and does not apply for 98% of installations]

 

[acrwc10]

408.36(B) Supplied Through a Transformer.
Where a panelboard is supplied through a transformer, the overcurrent protection required by 408.36 shall be located on the secondary side of the transformer.

[there is an exception, it is very restrictive and does not apply for 98% of installations]

That seems a little vague, are you sure about that?