I am needing to size a transformer for a new service. My problem is this. Well, one of my problems anyway. I only know that the voltage is 480, but I don't know anymore than that. I am certaintly not ordering one until I know. It is a new commercial building, maybe 2 years old. I am going to put in a 125a 208y/120 panel.

Is my secondary kva amperagex360? If so, would it be a 45kva? This is new to me, I am getting better but I am still a novice at 3ph services. How do I determine my primary amperage? Does not knowing my 480v type affect my transformer size or just the type that I order?

I looked at scotts drawings. Very helpful.