Hi emdrr, Welcome to Trainboard! I use the same wire that I used for my N Scale railroad, 16AWG speaker wire, but you can safely use 24AWG bell wire too, as our locomotives only draw in the 100ma current range, so for a DC railroad you are probably only running 1 or 2 locos, and drawing less than 1/8 amp at maybe 4-6 volts. Short circuit the whole shebang at full 8 volts and maybe it's 1/4 amp. Add accessories and it can go up considerably depending on what you add, but those go on the accessories terminal, so you can be safe and use 18 or 16AWG wire to be safe.
