Joe:
The University of Manitoba doesn't have anyone who knows anything about house wiring except the electricians employed there.
I talked to one major electrical contractor this morning and he tells me it's common to have current through the white wire. When they wire electrical outlets for kitchens, they will often cut the tab between the two outlets on a duplex receptacle and connect one outlet to the black voltage source and the other to the red voltage source. They do that because it's common for people to blow fuses or trip the breaker to the kitchen electrical outlet because so many things that get plugged in there draw high current (coffee maker, toaster, microwave, electric frying pan, etc.) So, by providing two 15 amp circuits to that outlet and sharing the neutral, you don't blow as many fuses, but any imbalance in the current ends up going down that shared neutral. If a toaster and blender are plugged in, you might have 10 amps through the toaster and 3 amps through the blender, and the difference of 7 amps will flow through the neutral. However, that same electrician told me that even through there is 7 amps in that neutral, there won't be any voltage in that white wire, and that violates the first principle of electricity. You simply can't have current without a voltage to drive it.
That electrical contractor suggested I talk to one of the instructors at Winnipeg's Red River College where they train electricians, and I did so. I could tell that instructor simply didn't know enough about the subject to have any confidence in his answer, and he suggested I talk to the engineering department at Manitoba Hydro.
Manitoba Hydro employees get every 2nd Monday off, and that just happens to be this Monday. I will talk to Manitoba Hydro's engineering department tomorrow.
Anyhow, I fully understand that such an "imbalanced load" (as described for a kitchen outlet) is not exactly what we're talking about. What we're talking about is a current and voltage in the white neutral wire due ENTIRELY to the red and black voltage and current sine waves not cancelling each other out.
I remain convinced that if those red and black sine waves don't cancel out completely, then there simply has to be a resulting current and voltage in the white wire. There's simply no other option. I'll talk to Manitoba Hydro tomorrow.