Originally Posted by
NTM
I have three full size machining centers in my garage that I run off an old no-name rotary phase converter I got off ebay 15 years ago. It was about 1,000 bucks. It's only 15 HP and was sized for my first CNC mill which I got rid of years ago. It's really too small for the machines I'm running now, but I haven't had any trouble. In fact we run all three machines at the same time pretty frequently, accumulating thousands of machine hours per year, with no trouble.
It's just my experience, perhaps I have been really lucky, but my machines (Fanuc OM-F, OM-C and OMiB controls) have not been real picky about power, or anything else.