Hi, this is my first post. While i am not new to models i am a bit unsure of wiring a block system for dc common rail. I have read that droppers to the main bus wire on the positive side should only be +- 3m or 10ft apart. Then others say every section of rail should have a dropper. I am just a little confused, which should it be. Thanks Rob
budgie3 ....While i am not new to models i am a bit unsure of wiring a block system for dc common rail. I have read that droppers to the main bus wire on the positive side should only be +- 3m or 10ft apart. Then others say every section of rail should have a dropper...
....While i am not new to models i am a bit unsure of wiring a block system for dc common rail. I have read that droppers to the main bus wire on the positive side should only be +- 3m or 10ft apart. Then others say every section of rail should have a dropper...
Rob, welcome.
You will find lots of opinions, some based on personal experience, but almost no scientific studies. Thus, to answer what is the "right" or "best" way to do things is at best based on limited personal experience. Which may or may not apply to your situation.
I have found that rail joiners do a poor job of both conducting electricity and holding rails in alignment over the years. They start out fine, but eventually the grip on the rails loosens for a variety of reasons. Using tight new rail joiners when assembling and laying track can delay the inevitable. The issue is that the rail joiners that work the best are the hardest to install. Tightening rail joiners every year or two for track that is already installed can also lengthen their useful service life. Redoing your track every 2-3 years takes away the fear of rail joiner failure!
Soldering rail joiners to the rail makes a much stronger and much longer-lasting connection - both electrical and mechanical. Some solder every other rail joint - which leads to a feeder every 6ft when using flex track.
When I hand laid track, I followed the advice of a master model railroader, and didn't use rail joiners at all. This meant that every piece of rail had to have a feeder attached to it (I used 24 gauge magnet wire). I ran a common rail bus in a loop under the layout, and soldered all the common rail feeders to the bus. The bus was 16 gauge braided antenna wire. All the block feeders were tied to a terminal strip with an 18 gauge run back to the block toggle.
On my sectional track Lionel layouts, I used a similar wiring scheme for the common bus and the block runs, just heavier wire. I would attach a feeder (18-20 gauge) every 6ft or so to both common and block side to avoid voltage drops due to track pin issues (same as rail joiners).
On my current HO layout, I started with just a single pair of feeders while I experiment with track arrangements and scenery. The number of feeders will be expanded to at least every other track section when things become more permanent. Where I don't use rail joiners, every section needs 2 feeders. Where rail joiners are not soldered, I believe in every section having the 2 feeders for long term reliability. Where rail joiners are soldered, I can go 2-3 flex track sections for each set of feeders. This is based on leaving rail joiners unsoldered every 3 track sections or so to allow for benchwork expansion and contraction.
Since the reason I have feeders as close as I do is because of my expectation of failure of the rail joiners, feeders are necessary in both common and the blocked rail. Running a common rail bus is an easy solution for the common rail feeders. And sets you up for easy conversion to DCC at a later date.
my thoughts, your choices
Fred W
There really isn't a standard distance for separating track leads, but I personally think that a drop to every rail section is overkill (especially for those who use sectional track.)
My technique is to put the drop for a continuous, ungapped rail somewhere near its center. Then I solder jumpers around every uninsulated rail joint. The key is to have a solid electrical connection to every length of rail, not one which relies on slide-on rail joiners. Some folks solder all those uninsulated joiners, but climate dictates that I have to leave mine free to slide.
Even using common rail, it's a good idea to cut gaps or install insulated joiners every 6 meters or so. That can simplify troubleshooting if a mystery short develops, and can also simplify installing detectors for a signaling system if you ever decide that you want one. My own layout design is such that my longest un-gapped length of rail is just about six meters long, on a layout that's 4.3 x 6 meters in extreme dimension with about 45 meters of first main track.
Chuck (Modeling Central Japan in September, 1964 - analog DC, MZL system, common rail)
I use flex track and put a pair of feeders to every section. Overkill probably. But adding feeders is cheap, easy and I never have to worry about power.