# DC To DCC Rewiring Questions - HELP !!



## rrman497 (Aug 8, 2016)

I'm considering rewiring my medium sized layout (150' double track main line, ten 15' double ended staging/storage tracks, etc) from DC common rail block wiring to DCC and I have a couple of questions. Will I have to cut additional gaps in the common rail to isolate sections? Will my 1990's Walthers #6 and #8 "non-DCC friendly" turnouts cause me problems? The frog is already gapped on both diverging tracks isolating it on that side but not the point side. I have NO reverse loops or any kind of reversing tracks. I need to know how much trouble I'm going to get into. Thank you in advance for any assistance you can provide.


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## mesenteria (Oct 29, 2015)

If you have gapped rails after the frogs, you'll probably be fine. I am not familiar with common rail, but generally what you have to do to keep trains running in DC is the same for DCC. Where there is a short in DC, there'll be a phase conflict in DCC...a short.

At the points end of turnouts, if the metal wheels make contact with the stock rail that is out of phase with its partnered point, you'll get a short. So, with DCC, it tends to get finicky. The NMRA gauge becomes quite necessary to ensure metal wheels don't make inadvertent contact with metal of opposite phase.

If you have power-routing turnouts (modern DCC-friendly Insulfrog Pecos are like that) at both ends of a siding, you are likely to have a short if one of the two is not lined for the siding. I have learned to connect the siding tracks to one of the turnouts and to leave the one at the other end gapped.


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## Cycleops (Dec 6, 2014)

Hello and welcome to the forum


You'll probably be fine keeping everything as it is, I should just try it and see. You won't need to isolate sections. DCC is much less fussy and simpler than DC. If your turnouts are the insulating type you might want to put a power feed beyond a turnout to keep it "live".

Good luck.


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## DonR (Oct 18, 2012)

Actually DCC wiring is much simpler than that
for DC with power blocks controlled by
panel switches.

The way I interpret your 'common rail' is that
one rail of the entire layout is electrically
connected. You then have insulated joiners or
a rail gap on the other rail between power
blocks.

Unless you intend to use DCC Boosters in
some of your power blocks, you really don't
need that extra wiring and you would replace
those insulated joiners with metal ones.

My room size DCC layout is a little smaller than
yours but it is essentially all one single power
block. I have track drops about every 6 feet
or so. They connect to a 2 wire power bus
from the DCC controller. That's all there is.

All turnouts are 'friendly' to DCC, yours
will be fine. If you have plastic frogs, nothing
need be done. If you have metal frogs and frog
power is switched when the points are
thrown, you will need insulated joiners in
the frog rails.

As with DC, if you are using 'power routing'
turnouts such as Peco Insulfrog, you will need
to provide a drop from the track frog rails
connected to them. Some prefer to permit a
spur track to lose power so they can park
locos with no power. The power routing does
that.

Don


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## Lemonhawk (Sep 24, 2013)

If your happy with the panel that controls the blocks, I would leave it as it might come in handy to isolate a problem. Essentially you unplug the main DC feed to your layout tracks and plug in the DCC track output. I would not suggest using a switch to make it "easier" to switch back and forth between DCC and DC. Too easy to get the wrong position and due damage (mainly DCC power damaging a DC only loco). This all assumes a non gargantuan layout. you can power 4-6 loco's with a Digitrax Zephyr or NEC unit (can't remember the unit as I don't use NEC). You may want to post a your track layout just so we have a better idea of what you really need. do you have some local experts?


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## MtRR75 (Nov 27, 2013)

DonR said:


> Unless you intend to use DCC Boosters in some of your power blocks, you really don't need that extra
> wiring, and you would replace those insulated joiners with metal ones.


You can leave the insulated joiners in place -- if swapping them to metal ones would cause major disruption of track and ballast to accomplish. As other have said, just connect the DCC power supply to the pair of wires that used to go to one of the DC transformers (say Cab A). Then switch all of your block switches to Cab A and leave the there. No need to remove or add wires -- other than those required by turnout issues.

If you have your block switches and your turnout switches on the same panel board (as I do). You might want to remove the block switches to neaten up your panel board. You could simply cut them out and jump a wire across where they used to be behind the panel board.


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## rrman497 (Aug 8, 2016)

*DCC Rewiring Questions*

Thanks everyone for the great answers. You have convinced me that it shouldn't be too difficult to make the switch to DCC. Can I ask a couple more questions? 1) I'm thinking of breaking up the layout into 4 power blocks, 2 for the main line, 1 for the hidden storage tracks and 1 for the yard area. I'm hoping that will help me narrow down problems when they arise. Should each of these be protected by a circuit breaker? 2)I typically will have 12 - 15 locomotives on the railroad at one time, with only 4 or 5 actually operating at once. Will I need a booster(s)? Sorry I have so many questions but you've given me more info than the train store I go to or the books I've read. Much appreciated.


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## DonR (Oct 18, 2012)

Some do like to break up a layout into power blocks.
I have found no need for it on mine. jThe reason some
with very large layouts use them is to permit trains to
continue running in some blocks even though there is a derail short circuit in another block.

But if you do go that route you will want to have
individual breakers on each. Many use the
Digitrax PM 42 which has breakers for 4 different
blocks in one device. You must have gaps or insulated
joiners in both rails between the blocks. No common
rail.

Incidentally, any of the PM42 sections can also be used
as a reverse loop controller.

http://www.digitrax.com/products/power-management/pm42/

My DCC controller uses a 1 amp power supply. I often
run 5 DCC locos at the same time. The power supply
temp does not rise.

Most HO locos made in the last 10 years or so have
efficient motors. Each will typically draw less than
half an amp and the slower you run them the less
they draw. Most DCC controllers can handle 5 or 6
locos running at the same time. Since you have
a large number of locos, you may want to
wire your loco storage tracks with an on/off switch
so their decoders don't draw any current.

However, if you plan to run sound locos or many
of your locos are older, you would want
to add a booster. A booster may be needed if you
don't shut off the power to your loco storage tracks
also.

Don


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