2 phase is where it's at. IMO of course.
FYI - Balanced 120v is still single phase. The most common residential and small commercial service in Canada and the U.S., single split-phase, 240 V, features a neutral and two hot legs, 240 V to each other, and 120 V each to the neutral. Neutral wire is the return conductor of a circuit; in building wiring systems the neutral wire is connected to earth ground at least at one point. North American standards state that the neutral is neither switched nor fused except in very narrowly defined circumstances. The neutral is connected to the center tap of the power company transformer of a split-phase system.
A balanced power transformer simply lowers the voltage of each of the hot legs down to 60v rms so that you can get 120 by wiring across the 2 hot legs. While you are referencing the two hot legs to each other it is still a single phase system.
Three phase power is most commonly used in the power distribution grid because if it's increased transmission efficiency over single phase operation. End user use of three phase power is most commonly found when powering large machines or heavy duty motors because of the smoother operation and lower level of surging compared to single phase operation (would be nice for a TT motor is it wasn't so damn expensive to bring three phase power into a home.)
Yes you are right... Sorry. This is accurate for single phase.
No apologies needed, it is a common misinterpretation.
For those who are less conversant with power grid technology, in a residential split phase system you have two hot legs (call them A & B) and a Neutral leg (which is connected to ground in your circuit breaker box. From this configuration you can get 240v across the two hot leads (for stoves, dryers, hot tubs, large air cond. units ect.) or 120 volts from either hot leg to the neutral. Although there are two hot legs, it is still only one phase (A to B, which are 180 degrees apart).
In contrast a three phase system has three hot legs (A, B and C). Therefore you get three separate phases (120degrees apart) A to B, B to C and C to A. (You can also reference each of the hot legs to a neutral just like in the split phase system).
(Pete, as our resident commercial power expert, please correct any misstatements I may have made.)