Many homes have 3 phase power brought to them. In the electrical box they are further reduced to single phase circuits.
When Biz said that someone changed wiring, it meant he was repositioning outlets on to a specific phase/leg.
3 phase is 4 wire service, 3, 120v lines and a neutral. the 3, 120v legs return back thru neutral leg, 120 degress out of phase to each other.
Electricity is delivered a multitude of ways as AC. Anyways thats why I said I understood about the different legs not being common for the mentioned technology.