I did similar a month or two ago. Macy's IT guy told me they had problems with cash register on same ckt as general purpose for the hand scanners and other items at the cash wraps, so they wanted "clean" ckt for cash register. I'm guessing the problem has more to do with antiquated servers and the 10baseT network the registers are on, but who knows. The plans I had only showed a dedicated, not IG, but I home runned back to panel with IG anyway. Same old story as most of these retailers, only a few we have worked for have installed the one isolated transformer on new installations for the IG's like Bob was talking about.