The goof proof way is to electrically isolate both rails at both ends of the siding. I cut gaps in the rail with an abrasive cutoff disc in my Dremel. To really do it right, cut tiny bits of sheet plastic and slip them into the gaps. This prevents the gap from closing up due to rail movement over time. Superglue the plastic bits in place, and smooth the completed gap with a file until it feels smooth under your fingers.
Bring juice (two wires, one hot, one cold) to one SIDE of the toggle switch. Run two feeder wires from the center contacts of the switch to the siding rails. Keep polarity straight, you need the north rail of the siding to connect with the north rail of the main line. If you get this wrong, trains will balk at entering the siding, or short circuit the power supply as they cross the gap. Feeder wires can be small, 22 AWG or even 28 AWG. Drill holes in the table to bring the feeder wires up close to the rails. Solder the feeders to the rail. Safer is to solder to the outside of the rails. Soldering to the inside hides the wire better but runs the risk of flanges hitting the soldered on feeder. Clean the rail with a wire brush in your Dremel. Hold the feeder in place with a alligator clip, which also serves as a heat sink to avoid melting plastic ties. Use two alligator clips to heat sink the ties on either side of the solder joint. Use a tiny dab of rosin flux.
Final tip. Use DPDT toggle switches. They are easier to find, and at some future time you may want to go with dual cab control and then you can just wire the second cab into the unused side of the toggle switch.
David Starr www.newsnorthwoods.blogspot.com
Hello. I am in the process of laying my track and wondering how to wire the sidings on my layout to an DPST to turn the power on and off so I don't have to remove every locomotive that doesn't run on the type of power I am using since I will have a switch to have DCC or DC when I want it. So if you could please just explain what I need to do to wire the sidings to an DPST and any necessary insulating or anything like that. Thanks!