DCC Bus questions.

**josef86** · August 7th, 2007, 09:28 PM

I have an nscale layout that is being upgraded to dcc. I'm not sure how to run the bus lines. I as thinking of using 16 awg (or do you think 14 awg is better?) for the bus lines. Feeders will be 22 or 24 awg. Would stranded or solid core be better? thanks. I have an idea how to run them but I'm not sure where to start or stop them.

**jlbos83** · August 7th, 2007, 10:41 PM

Originally Posted by josef86

I have an nscale layout that is being upgraded to dcc. I'm not sure how to run the bus lines. I as thinking of using 16 awg (or do you think 14 awg is better?) for the bus lines. Feeders will be 22 or 24 awg. Would stranded or solid core be better? thanks. I have an idea how to run them but I'm not sure where to start or stop them.

As far as the size of the bus wires, it depends on how long they are going to be. So it depends on the size of the layout. You can't go wrong with 14, and it is easy to come by. But 16 will be fine if your layout is smaller rather than larger. Stranded or solid doesn't really matter. Stranded can be easier to work with, as it bends more easily. Electrically it doesn't matter, so choose what works best for you. As far as where to start and stop, again it depends onthe layout. The objective is to minimize the length of the run from your booster to any point on the track. Think about that and work from there. If you post a pic of your layout design someone would probably make suggestions.

Jeff

GM · August 8th, 2007, 01:01 AM

Originally Posted by josef86

I have an nscale layout that is being upgraded to dcc. I'm not sure how to run the bus lines. I as thinking of using 16 awg (or do you think 14 awg is better?) for the bus lines. Feeders will be 22 or 24 awg. Would stranded or solid core be better? thanks. I have an idea how to run them but I'm not sure where to start or stop them.

Josef,

Point your browser to Mark Gurries DCC Presentations. Then select DCC Wiring for an exhaustive dissertation on the science of wiring for a DCC layout. Mark covers all of your questions and more.

Towards the end of the PDF file you will find a very easy to read discussion of the subject of selecting wire size for buss lines and feeders.

I hope this helps.

**josef86** · August 8th, 2007, 03:04 AM

I will have to check that out. Its a 4x10 layout. Its a single mainline, but is looped around in such a way to simulate double main. It has changed so many times, before I found a design I wanted to stick with. The pictures I have show this.

http://s98.photobucket.com/albums/l259/lordjoechu/

If could likly draw it out if it would help. One of the picture shows 4 track wide. Two of them are Eastbound and two are Westbound. (eletrically speaking).

**jlbos83** · August 8th, 2007, 08:04 AM

At 4x10 16 gauge would most likely be fine. Remember, the bus does not have to follow the rails, and there can be more than one coming from the booster. One idea would be to run a spine across the middle of the layout the short way, and then three or for double ended lines off of it a foot or so apart. Then just put feeders from the track to the closest pair of bus wires. No place would be more than about 6 inches from a bus, and no bus would be more than about 9 feet long, at the very most.

Ignore the dots, they just get things lined up.

__________________|__________________
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..........................Booster

**josef86** · August 8th, 2007, 06:23 PM

Okay, I will do that.

**josef86** · August 9th, 2007, 03:28 AM

Okay, I read everything and I have a couple of questios to make sure I read it correctly. If I choose to twist my bus cables I would be twisting the commen and main bus cables.

I am using red for main and black for commen. Or I guess we can call it a rail and b rail buses. So A is red and b is black. I would be twisting the red and black togather? (I would assume it the same idea as network cables having twisted pairs).

Now the real question I have is how do I terminate the end of a bus? Are the ends of the buses (Red and Black) connected by a RC coupler? Or did I mis understand that.

From what I can tell DCC to need extra attention to detail then dc layouts.

**mfm_37** · August 9th, 2007, 04:27 AM

Originally Posted by josef86

Okay, I read everything and I have a couple of questios to make sure I read it correctly. If I choose to twist my bus cables I would be twisting the commen and main bus cables.

I am using red for main and black for commen. Or I guess we can call it a rail and b rail buses. So A is red and b is black. I would be twisting the red and black togather? (I would assume it the same idea as network cables having twisted pairs).

Twisting the red and black bus wires is not really necessary on your layout. Won't hurt though. Red for Rail A and Black for Rail B is a good choice, NTRAK uses the same color code and it matches NMRA color standards for decoder rail pickup. Be careful that you follow each rail especially when the main loops back.

Now the real question I have is how do I terminate the end of a bus? Are the ends of the buses (Red and Black) connected by a RC coupler? Or did I mis understand that.

No need to terminate. Just tape the ends of the bus wires to keep them from shorting or connect them to the last feeds on the run. Good advice previously to locate the booster as close to center of the bus as possible. Keeps voltage drop to a minimum.

From what I can tell DCC to need extra attention to detail then dc layouts.

Not really. It's still two wires connected to two rails, same as always. Reducing voltage drop and using enough feeders is good for analog and DCC.

Martin Myers

**Gats** · August 9th, 2007, 04:37 AM

Red and Black or A/B for the DCC bus is fine. As long as you connect the track feeders the same, ie red to outside rail, throughout the layout so you don't have any shorts. For the bus I would twist them 6-8 times per metre for good measure. It doesn't need to look like a plait and if it's untwisted for 1/2 metre don't worry overly.

For the length of run indicated I don't see the need for a RC coupler. From what I understand it's needed for long runs where the possibility of 'ringing' or an echo is increased causing commands to become garbled and rejected.

Josef, look at it as more attention to detail for less overall wiring.

**josef86** · August 9th, 2007, 06:31 AM

I have started with the feeders. By doing the feeders first I can make sure I keep their lenght down. I remembered that in one place two of the tracks have a different polarity then the two tracks next to them. My booster is about as close to the center as I can make it.

I need to go out and by some 16 awg for the buses. My main priority at this time is to get all the power wiring done. So I can move on to the detection stage using CTI products.

Thanks for all the help.