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  • Model Railroading "Basics": Wiring



    1. Wiring a permanent model railroad with its track mounted on a baseboard begins with a pair of 1/16" holes drilled just beside the outside rails. If the holes are drilled between the ties they won't be noticed.

    2. Wire strippers make the job of wiring far easier. #20 gauge solid copper wire is preferred by most modelers. Use one color insulation for one rail and a second color for the other rail.

    1001 Model Railroading Ideas - Summer 1971 - Page 59 1001 Model Railroading Ideas - Summer 1971 - Page 60

    The modern model railroads operated on the two-rail system of supplying electrical current to the motors in the locomotives. The low, twelve-volt D.C. current isn't enough to give anyone a jolt but it does offer the chance for a lot of short circuits that the once-standard three-rail system prevented. The major problem stems from the track switches. When the electrical power is fed in from the point end, the switch itself with most brands of track, will control the flow of current to match the route that is set through the switch. If the switch is set for the train to take the siding there will be power into the siding but not on the mainline beyond the switch. Consider, for example, a double track oval layout with a single pair of switches providing a crossover from the inner loop to the outer loop. First, there must be separate lead wires from the power supply to each of the two loops. A train can then operate on either loop with no problems until you want to know the pair of crossover switches to route the train onto the outer oval. if the power source to the outer ovals's outside rail is the same polarity as the outer rail of the inside oval the train can proceed right on through to run around the outer oval. If the polarity of the outside rails is opposite, it's a relatively simple matter to swap the wires to the rails on one or the other of the ovals so the polarities will match. With just this simple double track oval and a single pair of switches, however, you already have two sets of lead wires, that must be connecting with matching polarity, before the single train will be able to operate over the entire system. The old three-rail model railroad systems avoided the polarity problem by making the center rail (which, by definition, always was in the center) one polarity and the outer rails that trains rolled on the opposite polarity -- three rails aren't as realistic as two but they did simplify the wiring for the model railroad builder.

    The fact that the track's switches control the flow of electrical current helps to simplify the wiring of most model railroad systems by eliminating the need for separate lead wires to each and every siding, but the need for these extra connecting wires is not totally eliminated as we have seen from that double track oval. Another complication stems from this type of switch-controlled current: the power supply must be connected to the point side of the switch (the area where the siding's rails and the mainline's rails actually join and break to route the train onto the siding or main line) for the current to be able to flow on into the siding. With some types of track plans it's not possible to connect a single set of lead wires and still have electrical power to all points of the track system. The N scale model railroad in the photos has two such sidings inside the oval; each connected by a pair of crossover-style switches. The power to these two sidings is "jumped" from the nearest powered track by a single connecting wire (one of the rails provides the second power connection). Further, it is not always possible to connect the lead wires from the power pack in such a way that they are located on the "point" side of all the switches. Again, "jumper" wires will be needed to provide electrical current to some parts of the track. All of these extra electrical connections can pose another problem. It is possible for one of the track switches to short out part of the system when set for one of the sidings. The only way to avoid these types of short circuits is to slice through the rails that would cause the short and drop in a small bit of glue to insulate the cut electrically. You need a good bit of experience in wiring a model railroad to spot each of these potential short circuits: the basic idea is to trace the path of current along the positive rail, with the track switch set first for the "siding" and then for the "main," to see if it ever contacts the negative rail. An even dozen of such insulated "gaps" are needed on the relatively simple layout in these photos! Rules and drawings describing the theory and principle of two-rail model railroad wiring are explained in detail in the $3.00 book: HOW TO WIRE YOUR MODEL RAILROAD available through your hobby dealer -- the basics of one-train wiring for the simple oval switching layout are just the start of what you'll need to know for control of reversing loops, two or more trains at a time, and multiple power supplies….



    3. Strip about 1/2-inch of the insulation from the ends of the copper wire and slip the stripped ends up through the holes beside the rails.

    4. Use needle nose pliers to make a pair of right age "L" bends in the wire so it will bend from the hole to the edge of the rail and then lay along the indented side of the rail without holding in place.

    5. Scrape any paint or grease away from the side of the rail and apply a drop of solder to the rail. Press the connecting wire against the rail and touch with the soldering iron. If the iron is hot enough you won't have to leave it right there long enough to melt the plastic ties.

    6. & 7. The insulating gaps needed to prevent short circuits (marked with the white squares on the oval switching layout photo) can be cut with a razor saw. Drop in a bit of white glue to keep the cut ends apart.

    8. We've connected the minimum number of wires and cut the necessary insulting gaps (white snares directly on the rails indicate where the hairline gaps are located -- the wires are shown on top of the table, here, you'll want them to pass through holes drilled in the table). This wiring scheme will require only one power pack and no extra on-off switches -- just throw the track switches to route the train and there will be power to run it. The power connections (shown coming in from the two opposite ends of the layout) are needed (but they can be connected to the same power pack -- just be sure the connection to the outer rail on one side of the layout and the outer rail connection on the opposite side both connect to the same screw on the power pack.

    1001 Model Railroading Ideas - Summer 1971 - Page 61 1001 Model Railroading Ideas - Summer 1971 - Page 62


    Article Details

    • Source 1001 Model Railroading Ideas
    • Publication Date Summer 1971

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