In Va, my panel box has two leads coming in, both 110, I wired my entire house and work shop. When a 220 appliance needs to be wired up one leg from both sides of 110 makes the 220 plus the common (ground). Now my shop in town has 3 leads, one 220 the other two are 110 (3 phase) plus a ground. Maybe other parts of the country has another setup ?? I have a single phase 220 RotoPhase motor (50hp) to manufacture the third 3 phase leg (220) to run the other machines. Like I said There’s only two legs of service cable (single phase 200 amp) coming into that box. I can take pics if you like. I might be not interpreting what you mean?