# DCC wiring question



## Aminnich (Nov 17, 2014)

Hey guys, the semester is coming to the end and its about time to get back to the layout. 

This week I have been doing some wiring. The layout consists of 2 4x8 sheets of plywood. I was originally just going to run a bus wire circle around the table. Im rethinking doing that. 

Should the bus wire be a loop? or should it have an end to it?

Also, should I have 2 separate power districts? (one for each table)

I have the command area centralized so i can see the whole layout fairly easily, I could have the bus wires separate coming straight out of the command each going to a different table. 

Thanks


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## mesenteria (Oct 29, 2015)

For a layout that small, place your controller unit mid-ships along one side, and make your bus, two 14-16 gauge wires, run T'd out in both directions under the long axis of the layout...centered. From there, cut into the insulation here and there and solder wrapped 22 gauge feeders up to about 3' long.


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## Aminnich (Nov 17, 2014)

I think a picture always helps describe what you are talking about. 










The sections of table are shown in orange. The 2 big rectangles and the 2 sheets of plywood, the other sections are fairly small.

Where the command is, is not changing. The length of wiring going to the right is a little shorter because of the section actually has more track for it to supply. 

Is this ok? Should the wires be connected? Should the sections of wire be simpler and shorter? Are those lengths ok?


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## Mark VerMurlen (Aug 15, 2015)

I think it's fine the way you have it. For the size layout you have, I don't think the little difference in wire length will matter. I wouldn't tie the 2 ends together, but it probably doesn't matter either. After all, the rails form a loop themselves on many layouts.

Mark


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## Lemonhawk (Sep 24, 2013)

No reason to tie the loop together and in general its not recommended. You may want each side on its own power district. If you don't want to mess with soldering to the buss wires you could use this connection







https://www.amazon.com/gp/product/B003JUVGLK/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1

Their wago luminaire connectors made for chaining a light bus.
You can see the black is one rail and the white the other rail with a connector going off to the actual rail which allows you to easily disconnect it to trouble shoot.
As far as power districts, its nice to isolate places where shorts typically occur (yards) so they don't affect the mainlines.


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## mesenteria (Oct 29, 2015)

I have no comment about the wisdom or necessity for looping the bus. I don't think it should matter because the rails it energizes could ostensibly be two parallel contiguous loops of nickel-silver metal, essentially 14 gauge wires themselves. But, I'm not sufficiently schooled in electronics to say.

I will say, though, that I have never done anything more than to tack up the two bus wire ends safely apart and to leave them exposed with the plastic insulation protecting them. This has worked flawlessly and consistently reliably on my buses running 20+ feet in each direction.


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## CTValleyRR (Jul 26, 2014)

mesenteria said:


> I have no comment about the wisdom or necessity for looping the bus. I don't think it should matter because the rails it energizes could ostensibly be two parallel contiguous loops of nickel-silver metal, essentially 14 gauge wires themselves. But, I'm not sufficiently schooled in electronics to say.
> 
> I will say, though, that I have never done anything more than to tack up the two bus wire ends safely apart and to leave them exposed with the plastic insulation protecting them. This has worked flawlessly and consistently reliably on my buses running 20+ feet in each direction.


I put a wire nut on the end to cover it, but otherwise I do what you do. My controller is in the middle of the U, and one bus runs in each direction.


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## mesenteria (Oct 29, 2015)

I just had a horrible thought. I hope nobody reading thinks the two wires of the bus can be wound and have a Marrett placed over them. 

Just in case some of us are as fuzzy as I am at times, we mean forming a closed loop of EACH OF the two wires comprising the bus, but separately. Just as you wind one colour wire with another of the same phase/colour in a light fixture box, and cover that wind with a Marrett (wire nut), you don't form a loop between the 'positive' and 'negative' wires of the bus wound together. That's vewy, vewy bad! Instead, the wire issuing from one of the two bus polarity terminals can only loop back onto itself...NOT over to the other polarity wire.

From there, we can debate whether or not making each wire loop back onto itself is a good idea.


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## DonR (Oct 18, 2012)

There have been many discussions of whether
to loop or let the DCC buss go to dead ends.

Allan Gartner is one of DCC's leading gurus. He
does not recommend it.

http://www.wiringfordcc.com/

Don


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## Mark VerMurlen (Aug 15, 2015)

DonR said:


> There have been many discussions of whether
> to loop or let the DCC buss go to dead ends.
> 
> Allan Gartner is one of DCC's leading gurus. He
> ...


I think the fact that there are so many discussions proves that it doesn't much matter. If it was clear that forming the loop doesn't work, there wouldn't be any debate and discussion about it. I'm also sure each side of this argument has some technical merit, otherwise again there wouldn't be any debate about it. So I would recommend following the leading guru's advice and not tie the bus ends together. But I also wouldn't lose any sleep if I had already done so.

Mark


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## Aminnich (Nov 17, 2014)

The only thing I can see why making a loop would be beneficial is if one sections need more power and the other has that power, but can't supply it to the needed section because they are not connected. 

Can you guys tell i am not good with wiring?

ALSO, this layout has 3 total "reverse loops" so, i am going to need help with those

Thanks for all the comments guys!

EDIT;

I wanted to include some pictures of wiring I got going on










Picture above shows how I have the bus wires separating. The wire going toward the top of the picture will be going into my command. And of course the other 2 sets of wires are my bus wires (no feeder connected yet)










Second picture shows how I have the wiring set up for between tables. Since I move a lot, I wanted all the wiring to not get in the way when I move again. So the terminal blocks are set up for between the sections of tables. The short piece of wire that goes between the tables goes through a hole in the tables. All my wires have spade connectors on them for easy removal and reconnecting them. 

Moving is a pain in the


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## Mark VerMurlen (Aug 15, 2015)

Looks good. Another suggestion is to come up with a color code for your wiring and stick to it. Looks like you're using red & black for your main DCC bus, which is standard. When you add circuits for switch machines or lights in your buildings, use different colors so you can tell them apart easily. Its also good to label your wiring so that you remember what it is several months or years later when you need to figure out some problem or you move.

Mark


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## Suncat2000 (Oct 23, 2016)

There may be some specific circumstances where tying the bus wires into closed loops would be useful, generally it's a bad idea because it will make troubleshooting power shorts harder. Especially if your bus wires are tied directly to the tracks instead of through some other device like a reverser. If you have reversing loops, those sections must be isolated anyway. My recommendation is not to make closed loops and make the distances from the power source to all bus ends approximately equivalent.

Sent from my SM-G930V using Tapatalk


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## DonR (Oct 18, 2012)

Aminitch

Post a drawing or photo of your whole track layout.
That's the only way we can efficiently determine what
needs to be done with the 'reverse loops' you say
you have. Three is a lot. 

Don


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## Aminnich (Nov 17, 2014)

Before I made a drawing of my track plan to scale (to the best of my ability)

Since my layout has 2 layers, I drew it in 2 drawings. The pink is the main loop. And the pink are what im calling reverse loops (I may be wrong calling them that)

Anyway, it looks like a wiring nightmare to me. 

First level;









Second level;









Thanks for all your help guys!


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## Mark VerMurlen (Aug 15, 2015)

You've properly identified where your reversing blocks are located. I would shorten the reversing block on your second level so that it doesn't include the 2 side tracks, if I were you.

One other thing for you to check, have you calculated the grade you need to get from level one to level 2? That might be a problem depending on the height difference between your 2 levels.

Mark


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## Aminnich (Nov 17, 2014)

Thanks for your reply Mark. The upper level reverse loop is as small as it can get. From where the loop begins and end is what i have marked. I just have sidings inside and off of the reverse loop itself. 

As for the grade, we talked about that in my layout topic. The link to it is in the bottom of this post if you would like to check it out. Ill send you a PM instead of getting this topic off topic.

http://www.modeltrainforum.com/showthread.php?t=53481


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## DonR (Oct 18, 2012)

Aminich

You have correctly identified your first level
reverse loop isolated sections shown in Yellow.

I agree with Mark that I would permit the track leading
to the two spurs in upper right to be part of main and
begin the isolated section a foot or so around the loop
from the spurs turnout and continuing to before the turnout mid right. However, there is no reason why you can't have the
track leading to the spurs, and the spurs themselves
as a part of your isolated section, just as you have
shown in yellow. 

You need 3 reverse loop controllers.
You might want to consider the Digitrax PM42. It
has 4 sections, each of which can act as a
DCC reverse loop controller. 

Don


Don


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## Aminnich (Nov 17, 2014)

would the digitrax pm42 work with the bachman easy command? 

In the past i have talked about getting digitrax, but for this layout, im going to stick with what i have and save the high expense for digitrax for the next layout.


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## DonR (Oct 18, 2012)

Yes the Digitrax PM42 would work with EZ command.

The input to it would be your DCC buss, each output
then goes to each of your 3 isolated sections.

Don


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