Bus Wiring (Demystified!)

I may be the dumbest model railroader around.  Or I may just be a normal guy who doesn't quite understand the language of electronics that I'm often confronted with in this hobby.   Thank goodness for the internet where I can find people to explain and clarify concepts that I don't quite understand!

One of those concepts, as you can probably predict from the title of this post, was the topic of "bus wiring".   For a long time I really didn't understand what this was or how it would benefit me.   I recall reading some manufacturers DCC instructions and coming across explanations like "Connect the red wire to the main track bus" etc....  Utterly confusing to me.

For the first several years of my layout (fully DCC), I was, in fact, able to get by just fine without really having to worry about this.   My wiring 'system' (if it can be called that) was to essentially use the Kato 3-way connectors in sort of a 'hub and spoke' arrangement to distribute power around my layout.   Imagine the below with three more 3-way connectors branching off to power the track.  This was my system and, for the most part, it worked.

For the most part ....because I was having some problems which I now know were due to my above wiring scheme.  I have three separate lines on my layout, all essentially concentric ovals that traverse the diameter of my rectangular layout (before my latest expansion anyway).  This gives these lines a total running length of about 15 feet or so.  The exception to this is the 'Blue Line' which uses gradients to double under itself and is effectively twice as long as the others....about 30 feet.   On this line I had been noticing some peculiar behavior with my locomotives....mainly a lack of responsiveness to commands.   I initially attributed this to dirty track, crappy Trix Mobile Station, poor decoder connection, or a variety of any number of things that could be potential causes.

As I started my expansion....and looked to add another 15 to 20 feet of running length to my main line, I started to question my 'lazy Unitrack' wiring scheme.  Fortunately, a post on the JNS forum was able to explain, demystify, and encourage me to do the 'right thing' and move to a real 'wire bus' (after first reading other members postings on what exactly it was!).

As I discovered, "Bus Wiring" has nothing to do with buses, trams, trolleys, etc.... it really is (as far as I understand anyway) the simple fact of laying down a 'main' power supply around the layout and then 'tapping' into this 'main' power line for your track feeders.  The below illustration is how I ultimately moved to a bus wired layout from the above 'lazy Unitrack' version:

For each of my four 'power districts' (the original 3 lines mentioned above, plus a new, separate section for all of the new yard tracks), I picked up 14 or 16 gauge stranded wire from the local automotive stores where I was also able to locate some handy 'suitcase connectors' which attach to the 'bus lines' and feature companion connectors that get crimped on to the 20-22 gauge 'feeder lines' that go to the track.

For installation, I usually tried to keep the length of my feeders about the same length as the average Kato power feeder.  I tried to do this consistently (for reasons that I'll try and explain below).  The below photo shows a Kato connector that is drastically shortened and I don't use on my layout, but it illustrates how you could continue to use the Kato connectors with this system if you choose to do so.

THE RESULT:
These electrically inclined people really do know what they are talking about!  My issues, particularly on the "Blue Line", with poor responding locomotives have disappeared!  The reason for this (covered in much more detail on the JNS Forum) is that on my longer routes, the actual DCC signal reaches the track at different times ---- granted this is in milliseconds---but it still (I believe) is enough of a delay for the decoder to get some sort of garbled signal from the DCC controller. 

Note that this 'responsiveness' issue I had on the "Blue Line" was not a problem on my shorter routes (I elected to upgrade them to a 'wire bus' anyway) so I do think this problem probably only comes up when you reach a certain threshold in terms of route length.  For small ovals, this will probably not be a problem, but as I experienced as I continued to add length, it was time for a better approach than the simple approach I was initially able to take.