If you're at the point where you need to start ballasting your model railroad track, then you might want to check out this video tutorial on wiring. Learn how to wire your model railroad track.
So, see how to run the feeder cables to power up your ballasts to power up your miniature scaled trains. You can use 12 or 14-gauge Romex house sheathed wire, or whatever you would like to use. Just make sure the electrical feed wire is big enough for your model rail transport system use. Get out your soldering iron and wire strippers and be prepared to give your scaled trains power.