Power bus gauge adequate

I'd say 18g is a minimum (for small layouts), and 14g is for larger room sized layouts...

I use 16g auto wire for the BUS on a 10' test track.

I could see 14g being the recommendation based on that being a common household solid wire size... cheap and readily available.

On a layout that size, I would stay with what you have, unless you see performance issues.

Are you feeding the BUS from a central location to minimize the distance that a loco can be from the controller?

On a small layout I would say that 18 Ga will be ample.

House  wiring is using 14 gauge for 15-20 amp circuits.

I don't think that you are ever going to see a 15 amp draw.

I went to the hardware store today-- I bought some 14 gauge and paid for it with change.  I suppose that's the beauty of a small layout. I realize that my 18 gauge bus will do, but i'd like to continue my practice of overwiring just so that when (if) I graduate to a larger layout I will do things correctly from previous practice.

 I'm looking forward to the WiringforDCC.com site when I have a little more spare time. . .

Thanks to everyone for your help.

With soldered rail joiners and shorter droppers (~4") every 3', you can successfully use 22g for droppers from a 16g bus...

Look at the maximum current draw for any 3' section of track, consider it's being fed from both ends by a dropper, look at the voltage drop over 4" of 22g wire, you'll see that it covers 'N' demands... Similarly you cab validate a 16g bus for small layout use... you will need to go to 14g for a larger and/or modular layout bus.