Another Polar Express set expansion question Larry:
To power a large layout I think i need two power tracks at third points of the layout. I have purchased more track including a second 10" straight power track and a CW80 transformer.

In order to keep the wall pack and its plug intact for future use with the original, small layout, I want to set it aside and use the CW80 with two power tracks.

So I intend to purchase a plug and pigtail to use with the plug in 10" straight power track and the CW80. The power track that I recently purchased has soldered wires rather than a side plug

This will give me two power tracks with connecting wires with braided conductor wire ends to attach to the CW80

So, my question has to do with which wire in the power wire feeds the center rail and which feeds the outer rail. I need to know this to connect the CW80 correctly and to avoid connecting one power track one way and the other another, opposite way.

Any help appreciated.