Even though the majority of the train control, including the gentle acceleration and deceleration, is done by seven of the Realroad's Whistlestop II's, there are still around 40 wire pairs to connect and keep track of.
The wiring scheme was devised ahead of time and despite a few blundering errors, turned out very well. The wire is in PVC pipe and, of course, the first error was the size of the pipe. You almost always need one size larger than you ran. The junction boxes themselves are ABS Plastic.
The second oversight was the rain water that seeps into the pipes. Even though The wire is pretty well water proof, the connections are not. We had intended to make the splices in the junction boxes underground-bad plan. Even a few hours underwater can dissolve an electrical connection.
That problem was solved by building the terminal blocks shown above. Not only do they allow all connections to be made above ground, they allow for the high connection density required. The center is open to allow a hose from a shop wet/dry vacuum to be inserted through a tight fitting hole in the 3" cap. Water can be periodically pumped out of the entire electrical plumbing system at one time. The connections are surrounded by a short piece of 3" ABS plastic pipe which is normally concealed by a small building.
Now a word about the wire size selection. There is a strong tendency in model railroading to either go too small or too large when selecting wire. #14 is large enough for almost any railroad except when running abnormally current hungry trains or the distance to the track is over about 50 feet, and #16 is more than sufficient for most short runs up to 20 feet. Large wire is hard to connect and conceal. Keep in mind that the equivalent size of a brass rail is a #10 copper wire and only has a resistance of about one ohm per 1000 feet. You should take advantage of that at every opportunity. On a single loop railroad, hundreds of feet in length, even though it is a always a good idea, it is not really necessary to apply power to the track at more than one location. Track joints should, however, be clamped together or have jumper wires soldered across them. Because of their short length, these jumpers can be very small wire, #18 is large enough. The total voltage loss on even the more power hungry trains would be less than a volt.
One of the simplest ideas on the TP&W is the accessory power and building lighting system. A 12 volt DC network goes throughout the railroad on a #14 wire pair. At dark, the polarity of the wire is switched. Devices such as smoke units, some lights, and some accessories that are not polarity sensitive, are powered right off the line. Devices that are polarity sensitive are powered through a bridge rectifier so they always see the same polarity. But the building and street lights are each powered through a diode . In the daytime they are off, but at dark, by simply reversing the polarity with an internal relay in the accessory power supply, the whole railroad comes to life.