Okay Ernieâ€” The rules for less than 600v. apply based on 230.200. The disconnect(s) will be "Service Disconnect(s)" and there are no Service Entrance Conductors. The overcurrent protection must be an integral part of the disconnect(s) or be immediately adjacent 230.91. The conductors feeding the xformers are feeders and the rules for overcurrent protection found in 240.101 apply. As for the grounding, the GEC will be the ground for the Service Disconnects and will be sized per 250.66 Note 2. As for 1 or 2 Disconnects I think either would work and which ever would cost less would probably prevail.
This is my opinion and I hope I've not missed something.
Hey Ernie- You going to Holland?