Before electrical work begins on the model railroad, electrical standards for how the cabling is going to be constructed need to be defined. Having a standard will help later so that faults can be tracked and it will be easy to know what wires are which.
Track Power Feeds
These will be 12-gauge cables, red for inside rail and black for outside. The track design I have right now does not have reversing loops, so polarity is not an issue. An example is this product. Each sub-roadbed section will have electrical connectors between the sections, like N-Trak.
The bus feed wires will be twisted, approximately 3.5 twists per foot to reduce inductance and noise on the cables.
The bus wires, as they do not form a loop must be terminated to avoid reflections. This will be accomplished using an RC setup of resistor and capacitor in series across the end of the bus. This page describes the electrical discussion on how to terminate the bus. Bottom line, the terminator consists of a 100 Ohm resistor and a 0.1 µF capacitor in series.
As I anticipate at least one DCC booster in addition to the command station, I will need a ground wire. This needs to be 12-gauge also and will be in green.
These connect the power bus to the track and will be made of 22-gauge solid strand copper wire, in the same color as the power feed.
Feed wires will be placed every three feet.
Any connectors between sections will be implemented using Anderson Powerpole Connectors, in the same color as the wire. These will be used to connect the sections making up the return track, connecting those tracks to the visible part of the layout, as well as connections to the staging yard.
Accessory Power Feeds
In addition to the track, from which some accessories can be powered is the need for one or more DC buses to power lights etc. on the layout.