Feeder Wires

[SchemerBob]

I am thinking of constructing a permanent layout (finally!!). I am hoping to eventually have a, say 270 watt transformer to power two trains at the same time, using the DCS system. But for now, since I don't have it yet, I am going to power one oval, say, 8 x 10, with one transformer, and the larger oval, 8 x 15 or 16, by another transformer. They are both 80-watt (one is the CW-80), and I plan to only run one train per loop at a time. The track I will use is FasTrack. My question is, how are feeder wires installed? Will the 80-watt have enough power to run its loop once the feeder wires are done? Thanks in advance! I just need some information so I can plan my layout accordingly.

[lionelsoni]

The amount of power you will need depends on the train, not on the track.  The track will introduce a voltage drop between the transformer and the train, which could be enough to prevent you from getting an adequate voltage at the train.  This voltage drop is the current drawn by the train multiplied by the resistance of the track.  It is hard to say just how much track resistance there will be; but a rule of thumb is that it will be about the same as 16 AWG wire, which is .004 ohms per foot.  The worst case is when the train is at the farthest end of the loop from the transformer, of course.  At that point, you have half the loop periphery between the train and transformer, in both directions.  So the resistance is the total loop length in feet, divided by 4, multiplied by .004.  Your train probably doesn't draw more than 5 amperes, which is about all your transformer can put out anyway.

If the voltage drop you calculate is more than a volt or so, you probably need a feeder.  Smaller than AWG 14 is probably not worth the trouble.  AWG 14 is .0025 ohms per foot; AWG 12 is .0016; and AWG 10 is .001.

You may wonder whether we're talking about both outside and center rails.  The outside rails contribute only half the resistance of the center rail, since there are two of them.  And you can reduce their importance more by connecting them together between the two loops, at the transformers and wherever else they come close to each other.  In any case, the estimation of resistance is so inexact that it is not worth worrying about the difference that they make.

[phillyreading]

You need to run feeder wires every five or six feet with tubalar track(10 inch sections) or every three sections of track when using GarGraves track, run the feeder wires in parallel to the main wires, A post to center, U post to outside rails.  If the CW-80 gives you any trouble replace it! Usually an 80 or 90 watt transformer should be able to handle most sized layouts unless running two or more locomotives or a lot of passenger cars as the light bulbs will take the power.

Any sections that behave badly and the multimeter don't show a voltage drop or resistance problem wire an extra set of feeder wires, a multimeter is a good tool but not always 100% accurate-even digital, I mention this because of experiance with Lionel tubalar track.

Lee F.

[lionelsoni]

If you're going to use the accessory-voltage output for anything that shares a common with the track, you will have to connect A to the outside rails and U to the center rail.  Unfortunately, this will reverse the whistle and bell functions.