Roy Smith wrote:
It is interesting that you mention that. It certainly is possible to

build a 4-phase generator. I've never seen or heard of one, but it
would be no big deal to build one. You would really have 4 windings,

not four brushes, but that's a detail.

Now, let's try an experiment. Label the 4 phases A, B, C, and D, in
order. Assume the windings are star-connected, so there's a common
neutral, which we'll label N. Let's further assume that the
leg-neutral
voltage of each phase is 120 VAC.

I'm going to give you two panels, each having three terminals on it.

One both panels, the terminals are labeled X, Y, and N. One one
panel,
X and Y are connected to phases A and C from our 4-phase generator,
and
N is connected to the neutral. On the other, X and Y are connected
to
L1 and L2 from a typical center-tapped 240V residential pole drop,
and N
is connected to the center tap. On both panels, N is tied to earth
at
the panel.

Can you describe a measurement that you can make, which will tell you

which panel is connected to the 4-phase generator and which is
connected
to the pole drop? You can use voltmeters, ammeters, power meters,
phase
meters, oscilloscopes, or any other tool or instrument you desire.
Assume, however, that both are ideal voltage sources, i.e. you can't
draw enough current from them to significantly load them down.

My claim is that you can't tell the difference.

Ok this is a bit dirty but you didn't mention bonding the 4 phase
generator to ground anywhere but at the panel.
So I would take both panels and remove the ground wire from the ground
bus in the panel ( watch for all the heavy arcing! ) then i would take
my voltage meter and read voltages from any leg to the ground wire
coming from the ground. Since you did not bond your generator anywhere
but at the panel if you ever lose ground ( screw loosens ,cooper loss,
thermal stretching) at that panel voltage will float and be different

M.E.Farmer