# dc layout coversion to DCC



## tr1 (Mar 9, 2013)

1.)Does the common rail wire have to be eliminated completely?
2.)should the 18 AWG bus wires be replaced with a up to12AWG

power bus wires. with 22AWG drop wires around 6to 8 inches

long?
Thank you!
Regards,tr1


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## CTValleyRR (Jul 26, 2014)

What kind of trains are you running? Marklin 3 rail? Because in either DC or DCC, you need one wire per rail for 2 rail track.

I personally use 16 AWG for my bus, but unless you have a very large layout, 18 should suffice.


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## DonR (Oct 18, 2012)

Tr1

A properly wired DCC layout has track drops
every 6 feet or so for BOTH rails. There is no
so called 'common rail' used. Eliminate all
of the insulated joiners you used to create 
the blocks you set up to run multi-trains on DC.

All of your tracks should get the same power.
You can temporarily set the 'DC power pack' selector switches
to one power source which will be the output
of your DCC controller. When you get the time
remove all of those switches and wires. They'll
just be in the way and could be a potential source of
electrical conductivity problems.

The only exceptions would be if you have any
reverse loops or you have a very large layout and
want to establish 'power blocks'.

Don


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## tr1 (Mar 9, 2013)

*dc to dcc layout conversion/wiring?*

The layout I'm working on to up grade to DCC was/is an all
Atlas controlled layout. It is a double mainline figure eight.

The two dc power supplies(MRC)supply power to the double

mainline. It was started before DCC existed.
And consequently the 18 AWG wire used to wire up the table were
sufficient to use single engine operation. I thought I had to put a heavier bus wire that follows the track under the table
with drop wires staggered in places. And do the quarter test to check the circuit breaker. The 18 AWG wires are of different lengths~5' TO 9' in length. Or so the long lengths vary because
the table is 9'x5'
Thank you for any comments on my up grade to DCC.

Regards,tr1


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## DonR (Oct 18, 2012)

Disconnect both power packs from all track
connections. Then connect your new DCC controller
to the Atlas switches per my previous post. Remove
all insulated joiners.

Save your DC power packs to power your turnouts
lights or any other layout accessories.

Have you installed DCC decoders in your old locos?
While some can run on a DCC track it is not
advisable since the DCC AC track power can burn
out the DC coils in the loco motors. Do not let them
sit idle on the DCC track ever.

Don


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## traction fan (Oct 5, 2014)

*Atlas "Controlers" ,"Selectors", etc.*



tr1 said:


> The layout I'm working on to up grade to DCC was/is an all
> Atlas controlled layout. It is a double mainline figure eight.
> 
> The two dc power supplies(MRC)supply power to the double
> ...


tr1;

If your Atlas track plan used their flat green,or yellow slide switch controls in fat flat black cases, then it probably did use common rail. Many Atlas track plans did use common rail. 
However, DCC is a different animal. What the common rail was common to in those Atlas plans was that it was common to the two DC power packs, and common to all the blocks on the railroad, since only one rail had insulated rail joiners. Does my description sound like it fits your layout? If so, you can disconnect both Dc power packs(and save them as DonR suggested.) You can also disconnect any and all Atlas controllers, selectors, and such. You won't need them for running trains on a DCC layout, but they might be useful for other purposes. 
DCC could be thought of as using "two common rails" though it's not usually described that way. Electrical blocks, and insulated rail joiners are not needed on a DCC layout as the same two, electrically continuous, rails are used by multiple trains. So you can either jumper around, or physically remove the insulated joiners and have one common track. I recommend leaving the insulated rail joiners in place, and jumpering them. At some point you may decide to split your now-DCC railroad into power districts, or just want to temporarily 3isolate a section of track for troubleshooting purposes. If you have drop wires on both sides of an insulated joint, just connect them to the same bus wire and that will bypass the insulated rail joiner(s).

Bus wire for a small layout doesn't need to be 12ga. 14ga. down to 18ga. will work. Bigger wire won't hurt though. Your choice. Your 5' long bus wires are fine, and even the 9' ones should be OK. If you actually have problems, you can always add a few drop wires.

The file below describes the differences between DC and DCC control systems.

View attachment How to build a better model railroad the first time 6.pdf


regards;

Traction Fan:smilie_daumenpos:


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## traction fan (Oct 5, 2014)

*Common rail*



DonR said:


> Tr1
> 
> A properly wired DCC layout has track drops
> every 6 feet or so for BOTH rails. There is no
> ...


 Don;

Just F.Y.I.

There is a DC control system called "Common Rail." It breaks up only one, of the two rails, into insulated electrical blocks. The other rail is continuous, unbroken electrically, and common to all the blocks and to both DC power packs. This common rail system isn't used much today, with one notable exception. Atlas, in their published track plans, usually does use this common rail system.

Atlas sells electrical control switches called "controllers", and "selectors" to operate on their common rail layouts. These are SINGLE POLE switches, not the double pole variety that we're more familiar with. As such, they connected/disconnected only the ONE running wire to each block. They shouldn't be necessary on a DCC layout since, with DCC, both rails are unbroken, and there are no blocks. 

regards;

Traction Fan:smilie_daumenpos:


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## DonR (Oct 18, 2012)

Hi TF

Yep, I knew about the common rail tho I had never
used it. The OP should eliminate the insulated
joiners used in that system.

Don


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## CTValleyRR (Jul 26, 2014)

DonR said:


> Hi TF
> 
> Yep, I knew about the common rail tho I had never
> used it. The OP should eliminate the insulated
> ...


I didn't. Good to know.


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## tr1 (Mar 9, 2013)

*Thanks once again for all the good information*

The dc blocks will be made into DCC power districts.
Thank you gentlemen!
Regards,
tr1


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## DonR (Oct 18, 2012)

You'll want to install insulated joiners in both
rails going from one power district to another.


Don


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## wvgca (Jan 21, 2013)

any luck getting two power packs hooked up ??
are you running common rail [one is unbroken] or not ?


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## tr1 (Mar 9, 2013)

*common rail op.*

One rail is common throughout the entire layout. block sections are insulated per Atlas wiring direction drawings. All wire is 18 AWG.
Regards,tr1


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