As to your first question, as others have recommended, one set of bus wires will do.
As to your second question, besides Wiring for DCC which is an excellent web site, the web site for Tony's Trains is also an excellent resource.
Here are a couple of links:
http://www.tonystrains.com/download/MRR-PowerDist.pdf
http://www.tonystrains.com/technews/psx_long_reverse_loops.htm
Rich
Alton Junction
This site is the one I always turn to.
http://www.wiringfordcc.com
Brent
"All of the world's problems are the result of the difference between how we think and how the world works."
I am going to thread-jack my own thread. Now, I am looking for a good article or book on wiring fundamentals. I need to step back and learn about power districts, reverse loops, etc. Any suggestions?
Richard
I was just gng to say if you plan to do detection and signalling, then perhaps two buses will make it easier later. But it will complicate today.
NP.
One down the middle will work fine. However, if you plan to have each track in its own power district you would need a bus for each district.
Martin Myers
One down the middle will be fine. That will translate into feeders just over a foot long. At the low current of N scale, not going to be an issue, unless you were planning on using #30 feeders. Even that would be fine, if you had enough feeders. Any voltage drop is a function of both the wire size and length, times the current. So over short ditances, you don;t have much loss, even for smalelr size wire. To get say a 1V drop with a load of 1/2 amp, you need 2 ohms of resistence - that's a LOT of even something like #24 wire. Almost 100 feet of it. So 18 inch feeders to the tracks from the bus wire runnign down the middle will be all but undetectable - consumer meters won;t be able to measure it, anyway. And there will be no visible slowing of locos. Don;t worry about it.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
How many trunks you have is really a function of how many cats you have.
On my railroad there are three levels of track, a single loop of track on the east table, and five levels of track on the west table.
LION has one bus around the main part of the layout, all three levels take power from this, and one bus that goes around each side of the loop tables. LION uses 18ga feeders, but that is because LION has access to lots of FREE 18 Ga wire. 20 or 22 ga will do you just fine.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
I agree with Elmer. If you are really concerned you could always use a slightly heavier gauge wire for your feeders. Or solder heavier gauge wire to your bus wires long enough to get closer to the track, then add lighter gauge wire to push up through the roadbed to the track. Good luck!
Just run a single trunk or bus. Running two is overkill.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
I am planning my next layout and it includes a 10' section with two rails, one in each direction, that are about 26" apart. Would you run a single trunk down the middle with longer feeders, or two trunks directly under the tracks with short feeders?