When we got an 8530 at work in the early 90s (needed a machine with a Nautilus bus for specific hardware testing), it was definitely a 3-phase machine and since we were in an industrial setting, I just tapped into our panel at the back of the warehouse and wired up a 3-phase outlet for it. It never sat on our datacenter floor as a result, but it really only ever had one purpose and that wasn't a daily driver. Too much power, too much heat for so few employees (at that stage of the company).
Interesting. Were the power supplies 3 phase input? Like you I have noticed that most pdp and vax gear just pull 120 volt legs off the 3 phase to balance power loads. So you can run them on a couple of 120 circuits. Outside of say the RP07 (which is a real 3 phase motor)
C
