Like in Toms post, I have a customer with a carpet/tile sales building with a 120/240 single phase service and they needed 480 3 phase 4 wire service to the same building for a granite cutting machine he was setting up to do counter tops.So I added the 2nd service to the place and located it on the opposite side of the building too.
I asked for permission to add the 2nd service from the AHJ. I also placed plaques denoting the other service at each.
shortcircuit
