Oh boy, I was starting to get confused here as well! When you said "Here it is created...." I assumed that "Here" was referring to the U.S.A., but I guess you meant the U.K. diagrams in this thread (I now THINK that's what you meant, yes?)
I couldn't quite figure what you were getting at about the red/yellow high side at first, but I think you must have been assuming that these were the high-voltage input to the xfmr. At least that's the only way I can interpret it, unless I'm missing something.
O.K., let's clear the confusion. The diagrams don't show the high-voltage side at all. The three xfmr windings are the secondary star windings of the low-voltage side, providing a 240/415V Wye output. Red, yellow, blue are the standard phase colors, black for neutral. So all four wires bracketed "Overhead lines" are the secondary xfmr output strung along the poles.
I showed the house tapped off the blue phase for ease of drawing, but some will be tapped red phase and others yellow phase. In many districts the same lines will supply 1-ph power for residential and 3-ph for commercial. As far as the basic distribution system is concerned, there are no separate xfmrs for 1-ph residential loads as in America (except for an odd remote house).
I thought leaving out the HV primary would simplify the diagrams; sorry if the omission has confused you!
The HV side of the xfmrs is almost always 11kV delta. The aforementioned single-phase xfmr for a remote house has an 11kV primary run to two legs of the 3-ph 3-w 11kV network.
Has that cleared the mists, or just made it worse?
