Bus Wiring for Layout?

Use pairs of bus wires - common and hot - for each loop.  14G or 12G stranded will carry current with minimum loss for layouts bigger than yours.  Use 14G or 16G feeders to the track at 4 to 6 ft intervals.

Thanks, John -- succinct and to the point.  Assuming separately controlled conventional loops, would you a) run a bus loop inside each of the 2 track loops, or b) split each bus into 2 branches to feed each loop?  The latter is shown below -- or does it make any difference?

#14 has been very good to me. Postwar stuff never ran so well as it does now

I used #14 gauge wire from my power source to two terminal strips, 1 common, and the other power. Then, from the terminal strips, two wires the same length to my track and it’s called Star Wiring. So, every 12 feet I have power. The wiring from the terminal strips are #16 gauge. I have 19 blocks using Lionel’s BPC’s, and using 1 TPC With 2 -180 watt bricks to each of the 19 blocks, then I have a newer Lionel 360 watt PowerMaster to the other side of the BPC’s to run the 19 blocks. Therefore, we have 4 continuous loops, and then dividing the power will allow 4 long passenger trains to run at any time. Most of the trains we run have two to four powered units pulling the trains. All under Lionel’s Legacy command.
Mikes Train House, many years ago suggested the star wiring method for command controlling our trains, it’s worked great for us. Lionel’s ASC’s accessory switch controllers, and BPC’s, block power controllers, allow the operator with Cab 1L, and Cab 2 controllers to turn trains on, tracks on, flip switches while walking around the layout following their trains. Word of caution, we used the new 180 watt bricks because if we have a derailment, it shuts down the power instantly, keeping our electrical components safe… The boards in these new locomotives are expensive…Happy Railroading Everyone

14 will be more than adequate, use speaker wire as both conductors are different colors. This makes it much easier. FYI on Amazon they have copper wire 14 200 feet less than 70 bucks. Pure copper 99 percent oxygen free.

I used #14 for my main bus and #18 for the short track drops.  I've had zero issues with any voltage drops, even running multiple MU'ed steamers with smoke.