> [...], especially since most electrical installations (even domestic) > are 3-phase.
This, I believe, must be location-specific. In North America, it is usual for domestic electrical feeds to be only two-phase (that is, they are the two sides of a centre-tapped secondary - the two hot wires are 180 degrees out of phase with one another). /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTML mo...@rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B