Thanks guys!
I hesitate to corner ground the delta because 480 to ground concerns me. However, I'm not sure I want to float the delta either, hence my question.
However, a delta wye step-up xfmr seems to be special order and costs a premium. I will let the customer decide.
The other question...
The xfmr rep. says that although their step-down xfmr can be connected backwards, the inrush will be 10X primary current. A true step-up xfmr inrush would be 4-5X primary current, but a true step-up xfmr would cost more.
I am concerned about tripping primary OCPD if I connect backwards.
