O scale newbie. How do I power a 40-50' layout?

Hi John,
I am just finishing up my shelf layout right now. Everything is up and running and I just need to finish a little trim. I will be posting some pictures and videos of it all very soon. Probably by this weekend for sure.
In answer to your question, the 80 watt transformer will work fine for your shelf layout. But, you MAY need to attach a few extra power taps to the far ends of the layout. These you can just daisy-chain along the track and attach them at multiple locations, or you can just take multiple wires right off the transformer in parallel, whichever is easier for your wiring. Also, for your extra lights, etc, does your transformer have a second set of outputs at a constant voltage? If so, you are good to go, otherwise, you would need an extra power source for these. I am running an older 75 watt MTH transformer, which does not have these, and also a newer 100 watt one which does.
My setup has 2 loops, with an inner and outer loop(see my build thread for a layout diagram). I have the 75 watter powering the inner loop (50 feet), and it only has a single power lock-on. The outer loop (95 feet) is on the 100 watter. This one has 3 extra power lock-ons. So we have 2 trains running at once through 3 bedrooms and closets, and they can cross at the junction of the loops. (Thanks again T-man for the layout idea!).
So basically, you can just set it up, and see how it runs. If you have a slow down at the far end you can just run a wire to there and tap it on if needed. I had a test track of 80 feet set up with a single lock-on and it only had a minimal slowdown.

-Rob

Hi John,
Yes, you can just solder the wires to the track or connect them however they are normally connected to your layout depending on your track type. For mine, I used MTH Realtrax, so there are "Lock-ons" that plug into the track and have wire terminals on them. There are similar ways to wire for Lionel tracks as well, or straight solder the wires. You can run wire to your first tap, then just daisy chain along from there to a further location. You will likely only need one more tap at the far end for your loop.
This may help also : I did a little testing, and with my O-31 curves in the corner of the room, I needed to have 1.25" of distance between the track and the wall to make the turn without bumping the wall. Then I just have about 3/4" on the outside of the shelf, for a total shelf width of 5". So there is plenty of space to run the wire alongside the track by the wall. At the corners, I just made a 45 degree angle shelf so it was easier to trim out. I originally wanted to hug the curve with a curved shelf, but this way really did not add much extra material.
Also, what turned out nice was that I used 1.25" 'base' trim on the front of the plywood shelves themselves...this gives them a little more substantial look, and also just hides the track, so it is a nice clean look. I will post some pics of them in the next couple days. They look better and less intrusive than I was expecting.
Actually, it was my wife who suggested going through all the walls and running in our room and the daughter's room on top of the original plan of just the son's room. So a simple 45 foot layout turned into a 150 foot double loop through the walls. It is sooo much fun to watch though!