I have a center tapped 20-0-20 transformer whose wire colors on the secondary are notated as follows:
c || c -------- blue c || c c || c c || c -------- green c || c -------- blue c || c c || c c || c -------- green
With a volt meter I have identified which wires connect to one of the windings and which connect to the other winding. However, I don't know which pair of wires is the top winding (in the diagram) and which is the bottom. Looking at the diagram, I want to connect the two middle-most wires so that current flows from top to bottom, but I might accidentally connect the two outermost wires so that current flows from middle to bottom then top to middle. Would that actually be any different than connecting the two middle wires?
Of course current will flow in the same direction in both windings.