DCC buss feed separation.

[jwar]

I am still running DC, However as I'M building my upper level now I want to wire for DCC. I have read conflicting things on how far to separate the buss feeds.
One friend stated separate the wires and the other stated dont worry about it.[%-)]

Being the DCC signal for engines pass down the wire, would too close of a separation beteen the two buss wires cause the signal to disapate a bit, reducing the signals strenght.

I know when setting up a compus in a boat one should twist the wires to prevent compas error, due to electrical interference. Would twisted buss wires have an adverse effect on the DCC signal. Asking this question to see how much rewire to do.

Thank you[^] , Have a great day...John

[cacole]

Don't pay any attention to the advice about separating wires -- I have used speaker wire and/or lamp cord wire for the main DCC buss wiring on a 20 x 40 foot HO scale layout and we have had no signal losses because of this type of wire at all. The frequencies involved in DCC are of no concern for "crosstalk" interference in wiring.

[tomwatkins]

I use 14 guage insulated copper wire for my busses. Both wires run through the same hooks under the benchwork. I've had no problems in nearly ten years of using the system.
Have Fun,
Tom Watkins

[Anonymous]

I use standard house wireing and have no problems. Marcel

[mcouvillion]

I don't understand where the idea comes from to separate the bus wire pair. You need both wires for the circuit, so they have the same command signal on them. On DCC, unless you are running two command stations and two totally separate power supplies on the layout (which I have never heard of anyone ever doing, even on the largest of layouts), the command signal, and voltage, on bus wire pairs are the same. You are not going to induce a voltage in an adjacent wire pair if it is at the same potential. You are not going to induce a command signal on the other wire pair because the frequency is too high and the voltage is too low (and the command signal is already there anyway). Twisting the wires is how to stop crosstalk from one wire pair to another. That is why Cat5 cable for hard-wired LAN networks must be twisted all the way to termination (and why some folks can't figure out why their home-wired LANs don't have the speed they should have). If you ran one of your bus wires directly adjacent to one of the 110V power wires for a motor or something that draws a lot of current, you might notice interference in the DCC system when the 110V device was working, but who would do that?

Not an issue.

Mark C.

[ClinchValleySD40]

Pre DCC systems like Dynatrol needed the buss wires separated. However for DCC it is best to keep them together, twisted together for better signal strength if you can.

[Anonymous]

The only advantage to separating the bus wires is that it makes it easier to add the track feed drops, especially if you're using the 3M-type "suitcase" connectors to connect the feeds to the bus. If you have long runs, then twisting the wire occasionally may help, but if your bus is under 50' or so from the nearest booster, you probably won't gain much one way or the other, so do what's convenient.

[rrinker]

[#ditto]

The high number of twists in Cat5 wiring are because of the signalling frequency. The frequency of DCC is MUCH lower, and twisting the wires that much will likely cause more harm than good. Plus I wouldn't want to even try twisting a pair of #12 wires that tight [:D]. A LIGHT twist might help over a long run, but isn't required by any means. Nor is it required to seperate the two wires by a significant amount.
What IS inportant is that if your cab bus has to cross the track bus, or any other non-DCC line has to cross the track bus, like lines to signals, they should cross at as close to a 90 degree angle as possible. 90 degree crossings result in the least amount of induced current flow from one source to the other, in technical terms, minimal inductive coupling. And it's probably not a good idea to bundle your track bus and cab bus wires together. But they don't have to be 4 feet apart, either.

--Randy