Basically the same procedure pictured by Mike CT, first clean soldering areas of outside rails rubbing alcohol to remove grease/oil if required, remove black paint from Gargrave Phantom rail center rail in area to be soldered, I use emery cloth and a nail set. On the two silver colored rails I would recommend that you solder the wire leads to the outside side(web) of these rails to prevent the wheel flanges from impacting the soldered joints, over time as you gain experience in locating the soldered joint position and solder bead, you will be able to solder the wire leads to either side of these rails with no wheel flange rolling contacts. The center rail has not wheel interference you can solder either side of this rail once cleaned.
I cut # 18 gauge solid insulated wire 12 inches long, one for the outside rail and one for the center rail, I also cut another wire 5 to 6 inches for the other common outside rail, for outside( common) rail I use white insulated wire and for the center(power) rail I use black insulated wire. After cutting the three wires to the required lengths, strip off the insulation 5/16 to 3/8 on both ends of each wire using a wire stripper.
I solder the black hot wire first, bend the stripped end 90 degrees and slightly offset bend this 90 degree bend backwards to that it will lie flush with the cleaned area of the rail, position to the bottom of the rail. Hold this wire in this position using spring clamps,pliers with a rubber band holding pliers closed or other device. Apply solder flux to this wire with an acid solder brush, I use a Weller 260/240 watt soldering gun and 60/40 electrical solder. Tin the solder gun tip with this solder and apply the solder gun tip to the wire-rail joint being soldered, when the flux starts to boil, apply the solder wire to the joint being soldered, the solder melts and forms a bead over the wire where attached to rail side, release the heat trigger on the gun, let the solder solidify by cooling, then remove the gun completely. Solder joint must be silver in shine, no gray color this is a cold solder, give the wire a slight hand tug to verify that the solder joint is secure.
Apply this procedure to the 6 inch and 12 inch white wires that are to be soldered to the outside(common) rails, once soldered and the soldered joint is verified by the slight tug test, and assuming that the track is attached to the train board, drill three holes of a diameter slightly larger than the wire outside diameter adjacent to the soldered joints on the rails, feed the soldered wires through the drilled holes, the 6 inch white wire to to be soldered to the other 12 inch wire , strip the insulation from the 12 inch wire at the location were the 6 inch wire contacts this wire, once the insulation is removed at this contact area, usually 1/2 inch, twist the stripped end of this 6 inch wire onto this stripped area of this 12 inch wire, apply solder, and wrap with electrical tape.
The 12 inch 18 gauge wire that is connected to the outside rails, should be connected to either 14/16 gauge stranded wire, this stranded wire is then soldered to the common bus wire, I use a 12 gauge bus and 14 gauge stranded wire for connecting the 18 gauge to the 12 gauge bus.
I use a block system with toggle switches, 18 gauge to 14 gauge/12 gauge to toggle switches and transformer power. To prevent voltage drops, I have power connects to the outside(common) rails and center (power) rails every 8 to 10 feet.
