The two wires you attached to your track with your starter set work well for a 40 x 60″ oval – but as your runs get longer voltage drop over the distance and joints can cause poor performance as your train gets further from the power source. The solution to this is a simple wiring bus. Not only will buses provided better power, on a large and complex layout, they can help keep the wiring neat and easy to maintain.
A bus wire is nothing more than a wire, or pair of wires, that carries power from the source around your layout. It can be tapped by feeder wires to connect it to the layout at any interval. These work for track, switches, accessories, etc. We highly recommend using different colors for each of your different mainline and accessory bus wires. This will make it much easier to trace a problem later.
Wire comes in many sizes in solid and stranded varieties. Stranded wire is really a bundle of smaller diameter wires wound together. Wire size is indicated by a number – the larger the number, the smaller the wire. Most house wiring in No. 12, solid wire. For your layout, we recommend a No. 16 stranded bus wire with No. 18 feeders. The feeders do not have to be as large because they are not as long and it is easier to attach the smaller wire to the tracks. Stranded wire offers better electrical flow (electricity flows around a wire, not through it) and it is easier to bend. We recommend adding feeders at least every 10 to 20 feet around the track.
For lights and other low amp accessories, even smaller wire can be used on the feeders. Lighted accessories should use No. 20 or 22 wire. Phone cable works very well for switch motors. It is color coded, easily available and cheap!
You can use “common rail” or “common ground” wiring to further simplify things. As long as your transformers are in phase, you can run one common ground wire for all of your tracks. Then simply run an additional “hot AC” wire for the center rail of each separate loop.The bus wires for your tracks and accessories do not need to follow the track itself directly, but it is helpful if the bus wires and the things they supply are close. This minimizes the length of the feeders and reduces the “spider web” effect under the platform. It is a good idea to keep wires supported by running them through holes in platform supports or using some of the many different wire anchors available at a hardware store.
In addition to color coding, wire tags are also available to mark different elements under the layout. Maintaining a wiring diagram or planbook with notes that you update with your progress is also invaluable for future additions and maintenance. While this may not seem too important in the beginning when you only have a few tracks and accessories, as the railroad gets more complex, you’ll be glad you took the time to keep everything neat and consistent.