Hi Jason -
Based on a combination of personal experience and advice received from others, here are some basic wiring recommendations. Others may have different opinions, and I hope they will contribute their thoughts to this thread.
1. Run a pair of heavy gauge bus wires around the layout. Use stranded or solid wire ranging from 18 gauge for a small layout up to 12 gauge (or even larger) for a large layout. The bigger the layout, the larger the bus wires should be. The two ends of each bus wire should NOT be connected together to form a loop.
2. Feeders should be 22 gauge or larger. If you can keep the feeders short (a foot or less), 22 gauge is large enough, at least for HO scale and smaller. You may find solid conductor feeders to be easier to handle, but stranded wire is fine if you prefer it. The stiffness of solid conductor feeders may make them easier to position for soldering to the rails and easier to push through small holes in your base board.
3. Install feeders for each section of track and each turnout. This may seem like overkill, but you will not regret it.
4. Solder feeders to the rails. Do not use terminal rail joiners.
5. Connect feeders to the bus wires either by soldering, using insulation displacement (suitcase) connectors, or with some other reliable means such as Posi-Tap connectors.
6. Use turnouts with frogs that are isolated from the rest of the turnout. Provide a means of powering the frogs (and switching polarity), especially if you run short wheelbase locomotives.
7. Do not depend on rail joiners to carry power between track sections. Rail joiners are great for keeping rails in alignment, but are not reliable for carrying power. Even soldered rail joiners can become poor conductors over time.
- Jeff