Wire and gauges for Garden Railroads
There are basically 2 types of wires that can be used for model railroad wiring - solid or stranded. The stranded type is more flexible and perhaps less likely to break or crack with repeated bending. The solid wire provides for ease of connecting it to screw terminals and mostly because there aren't any strands that can "wander over" to a nearby terminal and cause a short circuit. If you use stranded wire, it is wise to "tin" the ends so that you have a solid piece to make your terminal connections with.
Selecting the right gauge is important. If the wire gauge you're using is too small for the application, there will be too much resistance in the wire and this will either cause the device not to work properly or, worse, the wire may heat up too much and become a fire risk. Remember we may be only pushing 18-22 volts through our wires, but we have 10 AMP power supplies which can really cause smaller gauge wire to heat up. It is always best with electricity to err on the side of too large rather than too small.
The following is a list of recommended NMRA wire gauges to use for model railroad wiring for G-Scale trains:
o 22-gauge wire for lights and sound system hook up in locomotives
o 18-20-gauge wire for remote turnouts and locomotive battery connections
o 14-16-gauge for track feeders and jumpers between track rail joints
o 14-for track power bus
The case for soldering rail joints with jumper wire:
When we join our track sections, we are making a mechanical connection. Even with conductive grease, Aristo track screws, and rail clamps, the connection is still mechanical. This connection may fail over time due to weather, sun exposure or vibration. I am a big user of rail clamps which are good if the joint is correctly prepared. The ends to be joined must be cleaned and polished with a Dremel tool, conductive grease added, and the clamp tightly clamped to both sides of the joint. However, over time this joint will fail based on the above reasons.
Some people solder jumpers between their rail joints, which is the ultimate connection for electrical continuity. To do this, you need 14 ga. solid copper wire, your Dremel tool, rubbing alcohol in a spray bottle, a soldering iron with a large tip of at least 80 Watts, 60/40 solder, and resin flux paste.
Prepare and clean the joint with the Dremel Tool, spritz the area with alcohol to thoroughly clean it. Add the paste, tin the wire, touch the rail and then touch the tinned wire ends to the rail. Spritz the whole thing with the alcohol to remove the residual flux. With the right wattage iron that has a large tip, the danger of melting ties is minimized. Practice on some scrap pieces of track until you get comfortable with the technique.
You now have an electrically perfect joint. Over the years, a soldered joint may break loose from vibration. It is a simple task to touch the soldering iron to the loose wire and fasten it back in place.