We came across the following installation:
A 75 kVA 480-120/208Y step down transformer protected on the 480V primary side by a 100A fused disconnect switch feeds two 120/208 panelboards. These are two 42 circuit 225 Amp Main Breaker panels loaded to the gills (and contain mini breakers also) from the secondary of the transformer. The low voltage side current rating of the transformer is 203 Amps. As I interpet the code, with the 100 Amp fused disconnect switch on the primary, secondary protection on the transformer is not required.
There is probably not 450 Amps of connected load on the panels, but could someone please refernce what code sections either allow or disallow this installation.
Thanks in advance
