It would make negligible difference. Both legs comes from the same transformer (a centered tapped single phase transformer) and feeder anyway. Also, the electrician(s) who did the installation has to follow codes and best practice that require them to try and balance the load on the two "legs", so even if you believe in the negligible benefits, it would be very difficult to put the "noisiest\/dirtiest" loads on one leg anyway.\n\nAnother thing is, the 230\/240 V load such as the drier and electric range are connected across the two legs, they both could draw heavy currents, and spill "dirt" too in some cases.\n\n\n\nOn top of all that, there's a shared neutral, a shared ground, and EF "noise" doesn't need a wire to travel; so the two wires, by being in proximity, will effect one-another. \n\nIndeed: your power-supply will clean up most everything that's coming down the wire. If you have EF noise, it's almost certainly introduced *after* the power supply through RF interaction.