Camped at and RV and golf resort the other day, the pole feeding the clubhouse caught my eye. It's not very often around here you see a transformer bank in a delta configuration, unless it's in the industrial area of a large city. Then I noticed a small stub of an old neutral wire on the top spool below the cans. Looks like maybe this use to be a traditional Y configuration and got modified to it's current version. The incoming wires cross over the main parking lot and entrance, maybe they had a clearance issue and this is how the power co chose to resolve it.