Let us not forget that our wires essentially parallel the entire runs of rails, themselves not-so-great conduits for electricity. Yet, we never worry about how much rail we have on our layouts, do we...in fact, more is preferrably to many of us. So, if the rails don't seem to have much of an impact on the passage of electricity, why should the larger gauge wire below it? 16 gauge wire is plenty robust, and is larger than what is found in your common 50' garden extension cords. There are no expressions of concern about the lengths of 50, even 100' extension cords of the type commonly used at construction sites to power 10 amp reciprocating saws and table saws.
Go light, keep it simple, no need for trans-oceanic gauge cable for your 25-40foot runs on a layout.
This chart and calculator say that a 30' run of 16 gauge wire carrying only 12 volts and delivering 5 amps will suffer a voltage drop of 1.2 volts. Our DCC systems in HO deliver about 15 volts, so you may end up with about 1.0 volts drop...the calculator doesn't have that finely discrete a range of settings, so I am guessing...
At 8x13 feet, 14 gauge should be fine. Use stranded if you can IMHO.
You can also get these little scotchlock connections that they call suitcase clamps which run a feeder wire and your buss wire in the same connector. It's like a little compression saddle. I found them at Home despot.
Please don't use these connectors; when used on solid strand wire the actually cut a grove in the wire that are joined together. and when used with stranded wire that will actually cut the strands of wire thus resulting in the load of the wire (capability of the wire to carry its' complete load) being reduced and they will also oxide over a period of time eventually cutting the power through them off.
Jim
What would be a good alternative to use? We are very close to putting down and wiring up the track, and this thread has been very helpful. I thought about stripping an inch of the bus wire, and looping the feeder wire around that and electrical taping it, but that seems like a pain, especially doing it about 50 times... lol