I’ve been experimenting the last couple days and I think I came up with a good method to make tracks more prototypical looking.
Step 1: Take 18 gauge stranded feeder wire.
Step 2: Stick the end of a track spike into the middle of the strands of wire.
Step 3: tin the feeder wire end.
Step 4: Carefully pull the wire through the feeder hole next right next to the track.
Step 5: Flux the track
Step 6: Take the track spike head and hold it against the rail outside
Step 7: Heat the backside (inside) of the rail (Use heat sinks if your plastic may melt)
Step 8: Apply a small drop of soldering tin on the track spike.
Then all you have to do is lightly tug on the feeder wire pull away the slack.
I find this easier than trying to solder a wire directly under the rail.
I use #26 Bell Telephone 25 pair wire and just drill a single hole in between the rails and feed the wire drops down through.
I strip about an 1/8 inch off the end - tin it and then slip it under the rail - I bend a very small hook on the wire and solder it to the rail flange.
Once ballasted and weathered the wires can not be seen !
And if you can find them - you really need to get a life!
I prefer to do it the old fashion way except that I strip the insulation back far enough that the bare wire goes into the hole. This makes it easier to cover the feeder with ballast.
First off, I use solid wire, either #22 or #24, for feeders.
A sizeable percentage of mine are hidden in the solder joints of flangeways - frogs and guard rails of turnouts. Not only are they invisible, but they reinforce the joints.
The rest are simply soldered to the rail base on the side away from the viewing aisle. The only way to see them is by using a mirror.
Even running trains powered by two ancient open-frame motors per each, I have had minimal voltage loss at the tracks. IMHO, using #18 wire for feeders is gross overkill.
I use magnet wire (typically #24 or #26) for feeders. On handlaid track, I pre-solder the feeder to the bottom of the rail. I paint the rail and then feed the wire through a 1/8" hole between the ties and under the rail. Then the rail is spiked. Since I have yet to use rail joiners with handlaid track, every piece of rail gets a feeder. The amount of current drawn through any one feeder/rail piece is necessarily small, so the small feeder size is not an issue.
When possible, I hide the feeders in the soldered joints of frogs and guardrails, as Chuck does.
Using stranded wire, cut back the insulation, twist the wire and put a small L-shaped bend near the end. Tin the wire.
Then, use a thin piece of fine sandpaper to make sure the bottom of the rail is clean (especially if it’s weathered rail). Drill a hole as close to the rail as possible so the wire comes up under it, and solder it in place using an aluminum soldering probe. This works best if you have a partner hold the probe in place, or my technique is to attach a couple pieces of slag ballast to the probe with rubber bands and wedge it in to hold the wire in place.
I solder bare copper to the bottom of the track before laying it down. I drill holes away from the track and feed the wires to them. I have found that drilling directly underneath the rail can cause the track to distort as the feeders are pulled through. This method avoids that problem. Here is a shot of the track in place with feeders visible off to the sides. They disappear when buried in ballast.