Under the following scenario, I would be running a 240v to 480v, 37.5 kVA step-up transformer (L1+L2) at 240v from a single phase 120/240v main panel. The step-up transformer would then power a 480v single phase panel, which would be running to a some 480v to 120/240v step-down transformers at the location of a few devices.
My questions are:
1) Can I size my service and main circuit breaker to the applied load, which would be 200A?
2) I need a 2-pole 200A circuit breaker as the primary-only side protection for the 37.5 kVA step-up transformer in order to meet 125% of the amperage per Table 450.3(B) of the NEC. Can I have a 200A circuit breaker on a 200A panel?
3) Can the sub-panel have a smaller main circuit breaker (100A) than the circuit breaker for the transformer (200A)? The sub-panel would be within 50 feet of the main panel
4) Does everything else seem fine with the line diagram and panels?
Thanks for any and all help. I genuinely appreciate any time you take to look this over and respond.


My questions are:
1) Can I size my service and main circuit breaker to the applied load, which would be 200A?
2) I need a 2-pole 200A circuit breaker as the primary-only side protection for the 37.5 kVA step-up transformer in order to meet 125% of the amperage per Table 450.3(B) of the NEC. Can I have a 200A circuit breaker on a 200A panel?
3) Can the sub-panel have a smaller main circuit breaker (100A) than the circuit breaker for the transformer (200A)? The sub-panel would be within 50 feet of the main panel
4) Does everything else seem fine with the line diagram and panels?
Thanks for any and all help. I genuinely appreciate any time you take to look this over and respond.

