I am currently running the Digitrax super empire builder dcc system. My layout is a swithcing layout that is about 20 feet long with another 4 foot leg. I am going to break my dcc system into power blocks by using circuit breakers from digitrax. My only question about doing this is will that reduce the amount of voltage drop that I have at different sections of my layout?
Anything that involves feeding the track at multiple points will reduce voltage drop. If you want to be absolutely certain, you may still want to run more than one pair of feeders to each power block.
DCC Voltage Drops The answer is not really. The DCC circuit breakers are good for isolating sections of a layout. Therefore, a short in one section of the layout will not shut down the entire railroad. Voltage drops are more dependant on the gauge (wire size) and the length of the DCC power bus and feeders. Here are a few observations. Use at least 14 gauge bus wire. Use at least 22 gauge for feeder wires. Keep the feeders as short as possible. Use a feeder to each section of track (don't count on rail joiners to provide good electrical contract over time). Bob Perkins
In electrical terms (and assuming you haven't been a complete idiot) - no it won't. It will actually slightly increase volt drop as you are interposing more 'stuff' in the feed line, which will then have more resistance than a nice, continuous piece of copper cable. In practical terms it may reduce drop, as alluded to by jsiren above, by encouraging better practice on the part of the installer ... but we are back to how much of a numpty he was beforehand Depending on how many operators you will have, and whether you will be exhibiting the layout, I'm not sure it would be worth subdividing your layout with breakers. As Mr Perkins says, they really just allow the rest of the layout to remain uninterrupted when a problem in one section kicks off. If was just me and a friend messing around at home I wouldn't bother - a dropout for a few seconds once or twice a night wouldn't really be worth the $$ outlay.
No more than circuit breakers in your house reduce the voltage at the wall sockets. The real purpose is to provide isolation between circuits in the case of trouble by disconnecting the one at fault, leaving the others in service. That way when your toaster shorts out you can still watch the ballgame.
So what can I do to reduce the amount of voltage dropped? I have feeder wires evry 3 feet or so, will that help?
Nickle silver rail is only an "adequate" conductor, not nearly as good as copper. If too much of the current path is via the rails, then you can get unacceptable voltage drop at the loco. The classic approach is to use a copper "bus" for distributing power within each power block, dropping feeders from the rails to the bus every 3 ft or so. Power blocks with circuit breakers are not to reduce voltage drop, but to provide the isolation I spoke of in the case of short circuits. These frequently occur when running a closed turnout from the "wrong" direction, not an infrequent ocurrence on a switching layout.
I have the digitrax four zone circuit breaker. In order to wire four sections to that circuit breaker some of the wires are going to have to be awfully long, how do you avoid that?
I get the sense that we may be confusing terms a wee bit. Voltage drop and power pickup problems are not entirely related. Voltage drop develops over both distance and resistance, with resistance related to distance and also to the material of the conductor and its profile. Basically, the thinner a wire, or the poorer a conductor it is, the more resistance it has over a linear dimension....along its length. That is why we keep feeders short, but use good materials (copper being one) and keep them under 24". Pickup problems are due to physical connectivity...if the joiners are loose, for example, then power to either side of the join could be affected. An engine passing across the joint may restore power, and you'll never know there's a problem there, or it will disrupt the power and stall...in which case you'll suspect a bad joiner. Joiners fail because of either corrosion or simple physical incapacity to contact the rails properly due to splaying or some other issue. One of the best ways to ensure a joiner remains functional, both for keeping the rails in place and providing continuity between them, is to solder the joiners, and if you are going to do that, why not solder a feeder to that joiner at the same time? Soldering a feeder need only be done every other joint, but you don't need joints between every section of track. You only need to join and feed every pair of track pieces while the joins at the either end can be free floating for expansion...use a joiner if you wish, but let it float unsoldered. With + being a soldered joiner and = being a free joiner, here is what I mean: -----------+----------=----------+------------=------------+---------- I hope that is clear. Also, of course, dirty track, dirty metal tires, dirty pickups, broken wires,....all sorts of issues can result in poor power pickup. For managing shorts, we provide circuit breakers. If you are using a track bus, which is heavy 12-14 gauge wire running directly from your base station and paralleling your main line, but under the layout surface, you simple place a circuit breaker in series to either a sub-bus or to the individual feeders. I recommend using a circuit breaker on a sub-bus providing power to a district, or block, on your layout. Note that you can use a 12v automobile tail-light bulb as a highly effective, and very inexpensive circuit breaker. It is just as smart as the digital ones, but at 1/10th the price, or less. Wire such a bulb (1156) in series to one of the sub-bus wires. When you get a short in that district, the bulb will become the current limiter and glow brightly. It saves your decoders and it also indicates visually where your problem lies. Finally, about lengths of wire and voltage loss: we tend to exaggerate the whole thing in our hobby. I have a staging yard off my layout fed by a pair of long 22 gauge feeders. That 4' pair of feeders is at one end of what amounts to 30' of non-soldered mix of EZ-Track and flextrack. I have never had a power failure on that ad-hoc set-up. Every time I power the system, all engines parked on that yard come to life and will move when directed. I am not under any illusions...a time will come when something will give in all probability, but it sure is taking its sweet time if it is the open invitation to trouble that so many people insist that it is.
You make that the issuing fixture of a sub-bus at each of your four circuits. You have a 14 gauge bus running to the circuit device, which can be central under the layout. Off each output, run more 14 gauge wire, or you can safely drop to 16 gauge if you aren't going to be powering each district with more than about 6 amps. Your feeders will come off the four sub-buses. So, the subs provide you the reach you feel you are missing.
Yes, physically isolated by gaps in the rails so that the power supplying that district can only supply that district. You can use plastic joiners or simply have the gaps with the rails non-joined. This is best done on tangent track because curved rail wants to straighten, and cut rail on a curve will have a kink unless you can figure out how to prevent it. One way to do that is to actually place a permanent bend in the rail by bending it enough that it wants to stay curved when you let it go. When you go to cut it, either with a jeweler's saw or a diamond cut-off disk, it will not want to splay so much.
I use a Digitrax PM42 for power districts on my HO layout. Some are almost 30' long using #14 wire with feeders on every piece of rail. The PM42 is centered on the layout(20' by 25' area). I have maybe .5 volt drop at the most on those long power districts. As others have mentioned, do not rely on rail joiners to conduct power, and use feeders. Jim
