Conceptual question here. Not really positive if it should be asked here or in general physics... In U.S. grid power supply could the secondary winding in a step-down transformer providing split phase power be grounded at any point in the winding? Instead of calling the center tap neutral, if I use L1, L2, and L3 from 'top to bottom' where L2 is the center tap and L3 is grounded: Voltage between lines wouldn't change, but now voltage from L1 to ground would be the full 240 V, and voltage between L2 (center-tap) and ground would be 120 (so L3 is now the grounded conductor). The implications of this, if true, make me reel a bit, but would be enlightening.