Glad you got to see these to.
All of the lamps are 120 volts, IIRC there are no 240 volt loads served by either this board or its mate on the stage.
The supply is also IIRC 3 phase delta. (The poco here in So Cal which also serves the island had a huge love affair with delta, even using it extensively at the distribution level, 4-34.5 Kv.)
As I'd mentioned, I had a chance to see the main vault room. The main switchgear was mostly modern circuit breakers, adapted to an original bus structure from the old gear. It not only gave me the "willies" being in the same room, but the heat coming from it was considerable.
The transformers serving the building were benind a concrete dividing wall, with "Pillbox embrasures" (6x12 inch slots) so I could peek in there too. 34.5kV incoming, a trio of individual submersible type transformers wired with what looked like XLPE concentric cable primary and three large (500Kcmil?) secondary per leg.
The interior of the vault showed extensive blackening from a secondary cable fire and the failure of the original oil filled transformer some years ago.
If I can get to the vault again on my next trip, I'll try to get pics.