I am under the belief that North American residential power is a special case of two phase power adequately described by the term split phase. Clearly I am in the minority and want to be convinced otherwise but have not found any convincing explanation.

I always assumed there was a functionally or historical reason but I'm always met with an inadiquate theoretically explanation. Best I can figure it's contextual reason to help the people who work on motors or it's to differentiate from systems with two phases that 90deg out of synch. A theoretical explanation seems to require a unique definition of phasors or to define our electrical system by the loads we attach rather than the voltage source suppling the current with a zero point reference.

Here is my theoretical argument. Pretty simple. Transformers transform. With the secondary having a center tap, 3 wires, each pair of wires have either a unique phase angle from the other pairs or a unique magnitude, even accounting for direction. Now arbitrarily calling the center tap 0v. The other two legs are 180deg out of phase. (Note, grounding an edge would give the same phase angle but different magnitudes, still a two phase system.)

I am under the belief that North American residential power is a special case of two phase power adequately described by the term split phase. Clearly I am in the minority and want to be convinced otherwise but have not found any convincing explanation.

I always assumed there was a functionally or historical reason but I'm always met with an inadequate theoretical explanation. Best I can figure it's a contextual reason to help the people who work on motors or it's to differentiate from systems with two phases that are 90deg out of sync. A theoretical explanation seems to require a unique definition of phasors or to define our electrical system by the loads we attach rather than the voltage source supplying the current with a zero point reference.

Here is my theoretical argument. Pretty simple. Transformers transform. With the secondary having a center tap, 3 wires, each pair of wires has either a unique phase angle from the other pairs or a unique magnitude, even accounting for direction. Now arbitrarily calling the center tap 0v. The other two legs are 180deg out of phase. (Note, grounding an edge would give the same phase angle but different magnitudes, still a two-phase system.)