Mexico Wanderer wrote:
Only the n or the u of the sine wave can be occupied by any one phase. Even two phases occupy 66% of the total ampacity. Three phases will occupy 100% of the ampacity. This is why "measuring" neutral is tricky.
Only ONE PHASE is involved in 240 service. It’s not at all like 3 phase service. That the voltage difference between the two hot wires is 240 is proof of the two hots being in phase or you might call it 180 degrees out of phase as in 120 and -120 V. Their voltages are always equal in magnitude and opposite in polarity. In a 240 volt service there is only one neutral wire of the same size as each hot leg wire. When leg 1 supplies 50 amps and leg 2 10 amps, the current in the neutral is only 40 amps because leg 2 is the return for leg 1. When 50 amps on both the neutral return is 0 amps: only 240 volt is used, not 120. However in the case of the cheater where the two hots are connected together both have the same voltage
and sign all the time as if they were one double size wire carrying up to 100 amps so both currents must return on the neutral wire: that is 100 amps.
IMHO the confusion is caused by teaching young electricians that 240 volt services are two phased. A different term (leg) should be used to avoid confusion with 3 phase systems which are very different.
