How to Wire a Model Railroad for Block Operation the art of wiring a model railroad for multiple train operations with conventional DC power supplies isn't spoken about often. So lifting the switch up will connect the track wires to the lower bus, cab A. As with the block wires, use a heavy enough wire gauge for these cab busses. No. 14 or No. 12 should work for most applications.Author: Ryan Kunkle Wiring a Model Railroad Track | MRA Wiring a model railroad track is an essential part of any model railroad layout. Find out how important and helpful it can be to keep your wiring neat early on when wiring model railroad tracks.