# Wiring!



## alienbob

Hey guys I'm new to this forum and to model trains. I'm currently working on a layout using DCC. How do you guys do the wiring for the tracks and accessories? I think I know what to do but I would like to some expert help. Whats the best and safe way to wire everything? Sorry if this is the wrong place to ask this question. I'm new to forums too!


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## tr1

*DCCwiring best practice?*

From my research.14AWG wire is the minimum for the power buss.NMRA says left side of rail is BLACK(-). RIGHT side of rail is RED. Red=(+)Black=(-)NMRA sets the standards.Drop wires or feeder wires can be20 AWG. There length's here, are~ 6 inches or less. Buss wire lengths over 30 feet must be twisted 4 times per one foot.
your running of the single red and black wire power buss (NMRA standard). At the end of the power buss run. Filters should be added (snubbers an R/C circuit)the resister=120ohms 1/2 watt. The capacitor, is ceramic=0.1microfarad(uf)This R/C snubber circuit is soldered to the red and black ends of the twisted pare power buss pare end wires. If you follow these simple instructions which can be found on the web your decoder's may have a longer life span
Good luck wiring14 AWG minimum for power bus. 
Regards,
tr1


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## D&J Railroad

Yeah, what TR1 said.


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## DonR

Tr1 and Ken are right on. That's the way to do it right.

But, guys, you can scare the daylights out of noobies who perhaps
may have only a 4 X 8 layout and need only 2 to 4 track drops
to a simple red/black pair of buss wires from the controller.

AlienBob

Tell us the size and scope of your layout plans. It may be you'll want
to follow every suggestion that has been posted. But, if you are
going to start small, DCC wiring is utter simplicity... little more than a connection
from your controller to your track.

Don


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## Gansett

tr1 said:


> Buss wire lengths over 30 feet must be twisted 4 times per one foot.
> 
> tr1


Ok, why does the wire have to be twisted 4 times per foot?


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## raleets

JackC said:


> Ok, why does the wire have to be twisted 4 times per foot?


Keeps the juice dizzy?


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## alienbob

Tr1 is the man! thanks for responding to fast to my question! but i have a few more  what do you mean twisted? And I'm not sure about the whole snubbers thing is. Mind explaining that to me like like I'm stupid?


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## alienbob

My layout is 4x8. It has two lines. Looks like a beltway highway. One inner loop and one outer loop.


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## tr1

*DCC wiring best practices NMRA standardization*



alienbob said:


> Tr1 is the man! thanks for responding to fast to my question! but i have a few more  what do you mean twisted? And I'm not sure about the whole snubbers thing is. Mind explaining that to me like like I'm stupid?


I am delighted to further ex-
plain. And hopefully I can explain it for you to easily under stand. I'm just repeating what was said here and around the web. If these instructions are followed to the "T" Complications,
that may arise, will be greatly reduced. Down the road. Twisted means two items,like 2 ropes of...............

hemp,lets say. Now these 2 pieces of rope are wrapped around each other or(Twisted) until the the 2 pieces of rope becomes a single object. This object is a length of rope 30 feet long lets say.In this case the 30 foot length of rope wrapped(twistedtogether) to form one piece of30' length of rope).
The rope we are talking about here is actually to pieces of 14AWG. wire. One black(-) and one red(+).Now, at the end of the twisted pair, It is highly recommended that a filter is added soldered together. For when shorts occur(derailments) the energy produced is snubbed or minimized to where the high current(spike) will not destroy or ruin the electrical component's.


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## gunrunnerjohn

The primary reason for twisted pair wiring is to minimize radiated noise from the signals on the wire.


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## timlange3

Hi AlienBob, What TR1 says is correct. In practice, on your 4'x8' two oval railroad, running two power drops to each oval with an 18g bus and 20-22g drops would be quite sufficient. No need to twist the wires or use a filter at the end of the bus. DCC boosters react quite fast to shorts.

If your booster/command station is in the middle of the 8' side, I would run a 18g pair of wires from it to the left end and another pair to the right end. Then a 20g feeder pair up to the rails, with the feeder being no longer than 6". This assumes all your rail joiners are tight. Add more feeders as you think are necessary. I would suggest all your wire to be stranded wire, not solid. It will bend easier and carry slightly more current than solid of the same gauge.


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## NIMT

alienbob,
On a 4x8 layout there is no need for snubbers or twisting, completely worthless to you, now if you run a 100 x 40 layout then we'll talk. If you were to push a signal a great distance then you need twisting, snubbers, repeaters, and boosters!
Run a pair of #14 wires and put in #22 drops off the main lines and any sidings and a min of every 3 feet of track run and you'll be golden. 
Do not make the bus loop, just run it out and stop at the farthest point.


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## tr1

*Twisted pair of wires*

Also, I believe that twisting the pair of wires cancels out any inductance(noise, signal interference that will occur over a 30 foot length of parallel wire spaced to closely together.
the twisting assures a neater appearance, beneficial for trouble shooting at a later time.
Regards, 
tr1


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## tr1

*Best Practices*

Also you have to take in account for any possible future expansion. Lets say, in the future,
the 4x8 is expanded into a module, now what do you do. So that's why NMRA best practices should be followed. Cause no one knows what the future brings. I'm just saying,
better to be safe than sorry
Regards,
tr1


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## gunrunnerjohn

tr1 said:


> Also, I believe that twisting the pair of wires cancels out any inductance(noise, signal interference that will occur over a 30 foot length of parallel wire spaced to closely together.
> the twisting assures a neater appearance, beneficial for trouble shooting at a later time.
> Regards,
> tr1


Well, twisted pairs will add capacitance and probably inductance. However the major noise canceling property is the fact that the induced currents that might radiate from the wire are cancelled by the twisted pair. That's why when you look at communications cables, virtually all of them are twisted pairs or coax.


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## alienbob

Ok so a filter like a fuse? and at the end of the bus wire is where it goes?


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## prinefan5

Total newbie here. I have my 4 x 8 table done. Before turning it over on its legs, I was thinking to get some wiring done-- just BUS wiring now. Layout will be the KATO HO Unitrack WGH Plan set . Want to do DCC with NCE Power Cab. My question is, is this video on You Tube sufficient as far as simply doing BUS wiring? 16 gauge wire? Just zip tie the ends at the end? I worry wiring is going to be my nemesis. Many thanks.

http://youtu.be/ErgANuavh5s


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## DonR

Wiring for a 4 X 8 DCC layout is utter simplicity.

All you need for a layout that size is about 4 
evenly spaced drops
from the main oval, connecting to a buss which
I would run straight across the long axis. Connect
the buss at ONE end to your controller. As noted in
the video leave the other end unconnected.

This is not to say that the example in the Youtube
video was wrong, it's a slightly larger layout. 

Unless you have special circumstances there is no
need for further wiring complications. 

However, if you are going to have power operated
turnouts you might also run the control wiring for
these while you have your table bottom available 
for easy access. If you have several, run a black
common wire buss to tied them together. Each would
also get a Red and a Green wire from your 
turnout control panel buttons or switches.

Don


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## prinefan5

If I use foam board on top of the plywood, how do the feeder wires get through the foam? Just drill a small hole?


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## michael cuneo

To get wires through foam I've used coffee stirrer straws or any small diameter tube put wires in tube and push through.


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## flyboy34

We have talked about 4' x 8', I am in the planning stages of a 8' x 18' layout(DCC) and would appreciate the instructions as well. Feeder wires every 3' or what is suggested. What gauge wire is required for feeder? What gauge for bus? Solid or stranded?

Thanks for any feedback.


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## DonR

The NMRA standards many go by say, 14 ga for your buss, preferably red and
black, and if longer than 30 ft, should be twisted to avoid inductance
and electronic interference. It should be terminated at it's
far end. Do not make a circle.

The drops should be 20 ga. and some say every 3 feet. Mine support
6 locos running at the same time even tho they are spaced more widely
than that.

You might consider dividing your layout into two divisions each of which would
be powered through a booster. These would be isolated by insulated 
joiners. A layout of the size you are planning could have a number
of sound locos which soak up power quickly. If you plan ahead for
that they'll run smoothly from the outset.

Be sure to read the pertinent threads in the DCC forum

Don


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## flyboy34

Thanks for the info Don. Could you explain what you mean by a booster? Additionally, the gauge of wire you recommend should this be solid or stranded?

Thanks again for your assistance.


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## DonR

A booster is a power supply for your DCC layout. It takes the
digital signals from your controller and adds extra amps to
power your big locos with sound.

Until you have those big boys you may not need a booster.

When you have your layout split into to power districts, the usual
reason is to avoid shutting down the entire system if there is
a short in one district. This is done with either a circuit breaker
or a simple 12 Volt car tail light bulb in series with the track
in each district.

My room size layout is only one power district. Even tho I do at
times have up to 6 DCC locos (non sound) running at the same 
time my stock Bachmann controller handles it smoothly without
a booster.

I have always preferred stranded wire because the likely hood of it
breaking is nearly nil. A slight nick on a solid wire weakens it
and can result in an untimely break off and an uncomfortable crawl
under the table. 

Don


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## tr1

*Dcc guidelines for large layouts?*

I thought I read that twisting wires "when" the total length exceeds 30 feet....... twisting, cancels inductance between wires(Unwanted noise) and voltage drop. With longer lengths of wires, the suggestion has been made to add filters or snubbers. These filters are a resister, capacitor circuit that lessen the voltage spike reflection(noise). I hope this may be of some help. All these tips and hints can be found on DCC guidelines.
Regards, tr1


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## DonR

tr1 said:


> I thought I read that twisting wires "when" the total length exceeds 30 feet....... twisting, cancels inductance between wires(Unwanted noise) and voltage drop. With longer lengths of wires, the suggestion has been made to add filters or snubbers. These filters are a resister, capacitor circuit that lessen the voltage spike reflection(noise). I hope this may be of some help. All these tips and hints can be found on DCC guidelines.
> Regards, tr1


I get emailed postings from the forum Wiring for DCC. There are extensive
posts regarding end of buss run snubbers or terminations and the
reasons for them. They go into very complex electrical theories.
It is mostly pertinent to large layouts.

Don


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## tr1

*cheap insurance?*

I just mentioned about the snubber's. They supposedly reduce failures of electrical components, IC chips and such, decoders also. They absorb the spikes in current flow
(short circuits and derailments, things of that nature current spikes that shorten a electrical components life span. You see, I'm operating with a strict budget. I think the
snubber's/filters are a form of cheap insurance. Regards,tr1


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