DCC Wiring Advice Needed

[DMU-Fan]

Hello All! Some quick questions for the group. I’ve done quite a bit of reading on the excellent “Wiring for DCC” website, and near as I can tell, I’ve followed all of the recommendations there. The layout in question is 4’ x 8’. All Kato Unitrack. All turnouts are Kato #6 or Kato Crossovers. I’m using a small 5amp DCC system with no boosters (as I only plan to run two or three trains at a time, and usually a single or two locomotives per train). I’ll be using 14ga stranded wire as my power bus, with 22ga wires for feeders. I plan to use track bus feeder modules built by RPC-Electronics (https://www.rpc-electronics.com/mrrtrackfeeder.php). For reference in the diagram, the “Track Bus Feeder Module” will support one feeder (one positive and one negative) from the bus, the “Track Feeder Mainline Module” will support two feeders (two positive and two negative) from the bus, and the “Track Feeder Hub Module” will support six feeders from the bus.

With all of that in mind, some questions:
1) It looks like in certain situations the track bus wires should be twisted, and some should not. I’m thinking of twisting them, I don’t think that will be an issue, correct?
2) My wiring design is a loop out of the DCC command station and back in. From the “Wiring for DCC” website, it seemed like that was the best option. He also mentioned the option of not looping out of the command station and instead running two seperate directions out of it, with a snubber a the ends of those two branches. Does anyone have experience with these two options? Is one better than the other?
3) I think I’ve got the feeders in the right spots (red line on the diagram) to accommodate the need to have feeders every 3’-6’ AND have a feeder on either side of a turnout, but could someone just double check and make sure I haven’t missed anything?
4) I don’t think I’ve created a reversing loop, but (again), can someone look at the diagram and make sure I’m right on this one?


(Link to diagram below, apparently I’ve lost the ability to add photos directly to my posts)
https://share.icloud.com/photos/02aDMYoVtYYiV29pvuP59ao6A

[GaryHinshaw]

Please see below.  Have fun!

With all of that in mind, some questions:
1) It looks like in certain situations the track bus wires should be twisted, and some should not. I’m thinking of twisting them, I don’t think that will be an issue, correct?

This is a small layout, so twisting is optional.  I would say it is a matter of personal preference, as it should function fine either way.

2) My wiring design is a loop out of the DCC command station and back in. From the “Wiring for DCC” website, it seemed like that was the best option. He also mentioned the option of not looping out of the command station and instead running two seperate directions out of it, with a snubber a the ends of those two branches. Does anyone have experience with these two options? Is one better than the other?

I would probably opt not to close the loop.  You don't really need the Track Bus Feeder Module, you could just route the bus clockwise or counterclockwise around the full layout and terminate the bus at the end.  You don't really need snubbers here either unless you run into reflection problems.  (This would manifest itself as confused commands to your locos, but I have never found that to be an issue on my pike, which has long bus lines that terminate un-snubbed.)

3) I think I’ve got the feeders in the right spots (red line on the diagram) to accommodate the need to have feeders every 3’-6’ AND have a feeder on either side of a turnout, but could someone just double check and make sure I haven’t missed anything?

This seems fine, but I am not familiar enough with Kato switches to know for sure where the feeders need to be on those items.  I'd be willing to bet that it's fine as shown.  (Note that you don't show any feeders coming off the module on the lower left.)

4) I don’t think I’ve created a reversing loop, but (again), can someone look at the diagram and make sure I’m right on this one?

There are no reversing loops to worry about here.

[Maletrain]

The usual OEM advice is to not make a loop back to the command station with the track power feeder bus.

The technical concern is that the DCC signal could have multiple paths that would cause individual square wave ends to overlap.  Because the sharp rise and fall of the DCC square wave is what is detected to provide digital data communication, the concern is that the transmission of commands might get garbled.

On relatively small layouts, that has usually not been a real problem.  The electrical signals travel so fast that the overlap is insignificant until you get to very long bus wires.

People seem to love to argue about the need to avoid loops, putting electronic "snubbers" on the ends of track buses, and twisting the wires of the track bus.  So, doing a search on these subject usually doesn't provide a clear picture for beginners.

With the small size of your layout, I don't think there will be any problem with making the closed loop that you show.  But, it is just as easy to not attach both ends of that loop to the track power output of your command station.  If you decide to attach both and then later think you have a problem that might be caused by that, just detach one end of the track bus, so that it becomes a linear bus, and see if that helps.  You get very negligible benefit with respect to  track voltage drop by having both ends connected instead of just one end connected.

[DMU-Fan]

Thank you both for your comments and suggestions! Very helpful! I guess this means I actually need to start a Layout Build thread!