Larry,
Your answer applies to a high leg delta, not a corner grounded delta. There are only 3 conductors in a corner grounded delta system. There is only one voltage available and that is the phase to phase voltage. Most of the ones that I have seen were 240 volt. One advantage is that in many cases you can use single phase equipment for a corner grounded system. You only need overcurrent protection for the two ungrounded conductors.
Don
