The choice of wire gauge all comes down to the electrical performance level you desire for the layout overall. As one knows from the DC power days, by varying the DC voltage on the track, one can vary or control the speed of the train. The key point is the voltage on the track determines speed.
With the change to DCC, the track voltage is now set to the maximum allowed by the scale of the layout and is constantly on. The decoder is now responsible for controlling the speed of the motor.
With DCC, the track voltage regulation is the function of the booster design. Although with DCC the track voltage is always present at full voltage.
•Wire Gauge: Lower AWG # (American Wire Gauge) = larger wire size & lower resistance.
•Bus Run: The distance you can run the bus away from the booster.
•Wire Length: The length of wire (Out and Back) you need to buy.