I’ve been asked a number of times lately about layouts that just aren’t working correctly. There can be many different reasons why things aren’t working well, but more often than not I find the problems start when there’s a change or addition made. With your basic model railroading electrical wiring there are a few simple rules you need to follow to keep the trains running. And just to make it clear, this discussion deals ONLY with your basic DC (transformer) type system, NOT DCC.

Starting out, I always have people do the obvious. And you would think these should be a “natural”, but many people forget them. Like “Is The Transformer Plugged In”? Sounds silly, but you would be surprised! How about the track? Are all the connectors correctly attached together? Did you clean the track and the train wheels with rubbing alcohol? If you have dirty track or wheels, then the trains won’t run. I clean my track and wheels at least once a week for good performance.

The next thing to remember is never cross the tracks with any metal items. This will create a “short” and cause everything to stop working. If you have only a very simple loop and are having troubles, carefully check to make sure there’s nothing touching the track. Think UNDER the track also. (Is there a piece of Christmas tensile under there?) If you don’t find anything touching the track, next check all of the connections and wire ends. Any breaks, cuts or frayed areas? And finally your transformer might have failed. A Volt/Ohm tester can check this.

Now, if like me you want more action than a simple loop can offer, then you’ve added turnouts (switches). Turnouts are a wonderful fun addition to your layout, but can cause polarity problems. You can think of polarity as the power running in the track. One rail holds a “+” polarity, and the other holds the “-“ (with your standard DC power). With the DCC system, the rules are entirely different, but that’s for another article.

If your trains were running fine before you added a turnout, and now they aren’t then you probably have a “crossed polarity” problem. In the very simplest terms, that means you have set the rails to connect to the wrong sides. I have compiled a few diagrams to help here.

The first diagram shows a very simple siding, either on the inside or the outside of a loop. Look carefully how the inside rail connects to the inside rail, and the outside rail connects to the outside rail. This is a good thing! This should cause no polarity problems.

The second diagram shows a “loop within a loop”. Once again, you’ll notice that the outside rail connects in with the outside rail. And the inside rail connects into the inside rail. All is well here again, with no “crossed polarity”.

Now we come to a couple of “not so good” situations. The next diagram shows a “cross-over” track from one side of the loop to the other. Notice that the inside rail goes to the OUTSIDE rail! This will cause a “crossed polarity” situation, and a complete short. This will cause EVERYTHING on your layout to stop. When you’re setting up any track plan, make sure the outside rail ALWAYS goes to the outside rail, and the same with the inside rail.

And the last diagram shows a “turn-around” or return loop. Once again, notice how when the track comes together the outside rail connects into the INSIDE rail! And again, you have a “crossed polarity” and a complete short.

In the simplest terms, these last two diagrams show us a situation that will completely shut down your railroad. But what if you really want the track to go like that? Well, yes you CAN make the tracks go like that. But that’s another article all together.