Okay Bob, I think I have a better grasp of it now & using the outside rails will definitely simplify the wiring task. I appreciate you taking the time to explain the basics & thanks for the wiring tips!
I had wondered whether some of those blocks might be sidings that I didn't know about. I agree that four main-line blocks are very reasonable.
You've talked about a "ground wire loop". There should not be any need for any kind of "loop", except for the loop of the outside rails themselves. Track resistance is highly variable; but a good rule of thumb is that it is roughly equivalent to 16 AWG copper wire, which has a resistance of 4 milliohms per foot. In your case, the center rail does not contribute, since it is fed separately from your block wiring. Furthermore, the outside rails are generally in parallel, as are the outside rail joints; and your track as you say is new. So assuming 4 milliohms per foot is very conservative.
Your loop cannot be much longer than 20 feet, given the size of the table. So the total resistance is 80 milliohms. But a train at the farthest point from the transformer is only 10 feet away along the track and is fed from both ends in parallel. Each of these considerations halves the resistance, to 20 milliohms. Even a train drawing a whopping 5 amperes will see a voltage drop in the outside rails of only 100 millivolts. The drop will probably be much less, given the conservative assumptions made. This is why I doubt that any wire loop around the layout will make much difference.
It doesn't matter where the second transformer is connected on. I expect the simplest wiring is to connect the two transformers together side-by-side, U terminal of the ZW to A terminal of the 1033. However, your ZW has four adjustable outputs, two of which are intended for just the sort of accessory operation you are planning. I would run the whole layout from the ZW and save the 1033 for your workbench and for occasional floor running away from your house, which is what I use mine for.
As for "phasing", many folks run trains (I say unwisely) between blocks powered by different transformers or by different outputs of the same transformer. The latter practice actually creates a fire danger, unless the two transformers put out exactly the same waveform, frequency, phase, and voltage. In both cases, there can be arcing and voltage spiking, but particularly when the phase is different, as it can be in the former case. Even when blocks are switched between transformers to avoid crossing between differently powered blocks, mistakes occur. That alone is enough reason to get the transformers in phase with each other.
But that is not a concern in your case, since each of your separate lines will be powered by a single output of a single transformer; and trains will not be able to cross between lines, as I understand it. In that case, powering the accessories from a transformer out of phase with the track transformer and using the same return (the outside rails) can actually reduce the voltage drop. The return currents through the rails cancel each other to some extent, and reduce the voltage drop. Your ZW's circuit breaker trips at 15 amperes and your 1033's at 5 amperes. If they are in phase, the maximum return current is 20 amperes (requiring 12 AWG rather than the 14 AWG I mentioned before). But, if they are out of phase, the return current would be only 10 amperes with each delivering full power. (The worst case is still 15 amperes, because the ZW may be delivering full power and the 1033 nothing; so 14 AWG is still required.)
One easy and useful thing that you can do with your two-loop design is to connect the outside rails together, loop-to-loop where the tracks come close together. Having the two loops' rails in parallel will further reduce the already very low voltage drop.
Bob Nelson
Thanks for your reply Bob. I seem to have a propensity to over complicate things plus I've been reading a couple of toy train wiring manuals. Except for the 1122 switches, the track is new and I am planning to use a distribution block & toggle switches for the center rail wiring.
The reason for the isolated blocks is that I want to run two trains on the main loop. I'm thinking that it would be convenient to be able to park one train on an unpowered area on the loop or a siding while operating the other train. I plan to power the accessories on the "operating" siding (which include a horse car, cattle car, & milk car) with the 1033 so that the voltage can be easily adjusted, independant of the rest of the loop. The section of track where the 622 switcher is parked on this siding will be isolated for power down during accessory operation.
I've basically divided the rest of the main loop into four quadrants. I'd also like to try to wire a 151 semaphore with the blocks to run both trains simultaneously per the 1949 Lionel operating booklet.
Of course, the reasoning behind the perimeter ground bus would be to save on wire & accomodate feed taps. So wouldn't the common terminals of the two transformers need to be connected to complete the ground wire loop?
I'm a little surprised at your comments regarding transformer phasing as the wiring books seem to indicate that it is important for proper layout operation.
Yes, the U terminals are already connected together inside the ZW. All you should need to do is to connect one of them to the outside rails of both loops (using at least 14 AWG wire). Unless your track joints are really bad, you should not need any other feeders for such a small layout, much less a wire following the perimeter. (Any accessory can pick up its common from the closest track.) The 1033's A terminal, not U, is the natural terminal to connect to this common. Lionel wired the single-output transformers differently from the multi-output ones like the ZW.
There is no need to have the transformer outputs in phase. In fact, if they are out of phase, there will be a small reduction in voltage drop in the common wiring. Actually, I think it likely that the ZW has plenty of capability to handle your accessories on one of its otherwise unused outputs.
I'm curious about the purpose of your seven blocks in such a short main line. You say you are powering all of them from one of the ZW outputs; so I'm guessing you intend to put an SPST switch in series with each one. But why so many?
Hello all! I'm finally to the point of starting to wire my layout (conventional) and I'm not quite sure I understand exactly how to connect multiple transformers correctly. I'm running two independant loops of 027 tubular on a 9' by 4' platform with a 2' by 3' addition (to make an L shape) on one end. I have one simple loop surrounded by the mainline loop which follows the perimeter of the platform and includes a passing siding and an "operating" siding.
I'm planning on using a postwar ZW to run the trains and a 1033 to power the operating accessories (cattle car, milk car, crossing gates,etc.). I want to use the "A" circuit for the mainline and the "D" for the small loop. The mainline will incorporate seven insulated blocks.
Now for the questions...are the "U" terminals on the ZW connected internally? If so can I start the common ground wire bus at the "U" terminal that corresponds to the "A" terminal of the ZW, run it around the perimeter and return to the "U" terminal of the 1033, then connect from there to the "U" terminal of the "D" circuit of the ZW? Will this complete the bus loop correctly? I know that the transformers will need to be "phased".
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