Here's a few more tidbits on the subject...

Here in California, and probably other places as well, a typical electrical feed for a house coming from the utility consists of a single phase 240 volt feed coming out of a center-tapped transformer (in my case it is 12,000 volts into the transformer and 240 volts out).

The center tap is considered the neutral and is bonded at the service panel entrance to an earth ground. At downstream subpanels, the ground and neutral connections are separated.

Anyways, each hot wire at the service entrance measures 120V with respect to that center tap neutral. So there is 240 volts between the two outer legs.

Sometimes people will refer to this arrangement as "two phase", but in reality the home is fed by a single phase circuit (in my case, 12kV). The two 120 volt legs are 180 degrees out of phase with respect to each other. If they are loaded equally, there would be no current flow in the neutral...

I hope that helps and doesn't cause too much confusion...

Randy