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Power arrives at 480 V, with three 208 V boards behind it.
A single 480/277 V, three-phase service feeds a lightly loaded 150 A panel that serves the fan-coil units and a step-down transformer. The transformer in turn feeds three 208/120 V panels on 250 A frames, installed in 2010. On paper that is generous power for the incoming format. The transformer's rating plate was no longer readable, and its kVA is the number that sets the real ceiling on the 208 V side.
What we recommended
Get the transformer rating from the building's records before the equipment layout is fixed. Everything else on the electrical side can be planned around it.