I solder 12 inch long wire to the outside rail and a 6 inch long wire to the other outside rail, wire is #18 gauge insulated solid. I use the solid wire because I remove the insulation 1/2 inch from both ends, one end is then soldered to the bottom of the rail web, this stripped end has a 90 degree offset bend, I use test wire alligator clips to sold these wires in position for soldering. Soldering is done with Kester 60/40 solder and 200-250 Weller soldering gun.
Once the 12 inch wire lead is soldered to one outside rail, I solder the the 6 inch wire to the other outside rail, then both wires are aligned side by side, the insulation is removed from the 12 inch wire for soldering the 6 inch wire to this wire, once the insulation is removed, is use lineman electrical pliers to twist this wire onto the 12 inch wire,joint is the soldered and taped with electrical tape. The free end of the 12 inch wire is then butt
spliced to #16 or # 14 gauge insulated wired for attachment to the # 12 gauge buss wire. Once the wires are taped I drill a 1/4 in diameter hole through the train board and route the outside common and center hot rail wire lead through this hole under the train board, soldering of the hot wire lead to the center rail requires removing the black rail
coating, same soldering procedure, this wire is butt spliced to # 14 or # 12 gauge stranded wire which is routed to toggle switches and track power, I use the block system.
I check all of the soldered track-wire connections using a continuity tester with a integral light. It may be redundant to wire both outside rails but I figured it may take additional in track wiring initially but it should prevent possible power losses in the future.