sub busses : LUSENET : Wiring for DCC : One Thread

I'm considering going to dcc. Right now, I'm reading on the subject to understand it before buying anything. In the "track wiring" section of your site, you say "consider putting in sub busses ..." I just can't figure out what can be (or look like) these sub buses ? I think I need some drawing.


-- François Turcotte (, February 15, 2003



Sub buses are more of a concept that something to see. Probably not exactly what you wanted to hear. I'll see if I can help out.

Look at section 5-6 of

There is a drawing there that has sections labeled "sub bus" and it says "perhaps a town in size." I show light bulbs, toggle switches, you can use an electronic circuit breaker - or nothing at all to seperate the sub bus from the main bus. The key thing is the concept of a sub bus - a smaller section of bus that somehow can be isolated from the main bus and booster for troubleshooting purposes.

You WILL need this! I have seen too many cases where a club had to take a set of wire cutters and cut up their main bus to isolate their problem.

I see in my drawing, which is one of my earliest, that I suggest green or clear. You can still do this. I have since decided to use green for my reverse loops. What I do instead for my sub buses is use a smaller wire. In the US, I use #12 AWG for my main bus and #14 for my sub bus. I have to admit, this works for ME, but not for a lot of people who don't work with electrical things every day. To me, the difference is size between #12 and #14 is as obvious as if they were different colors. But the average person can't readily tell the difference. If you can readily tell the difference in wire size, you can use this approach. Otherwise, use a different color.

When I say that a sub bus is a concept, that means you don't have to use a wire to create the sub bus. I have several places on my layout where they there is no obvious sub bus. This occurs where I have wires coming to a terminal strip. See my section on parts and you will see a special jumper sold for terminal strips. Jumpers going from screw to screw to screw are the sub bus.

As you might guess, your main bus could also be a collection of terminal strip jumpers. I have that, too. These things tend to happen under yards where there are a lot of tracks and a lot of wires. The terminal strips help make it easier to know where all those wires are going.

Note: I like to use terminal strips near the front edge of the layout. I can troubleshoot most problems without going under the layout. (I have a disease that will eventually make it impossible for me to bend over. So I'm planning for my future.) Terminal strips raise your cost and if you are not careful to make good connections to them, they can cause you problems. If the cost isn't a problem and you make solid connections to them, they do provide a convenient disconnect place for troubleshooting.

Look at 5-6 carefully and read this. Hopefully, this will clear up what a sub bus is.

-- Allan Gartner (, February 16, 2003.

Moderation questions? read the FAQ