Buiding a 'Ready for DCC' Layout

[AndyRAP]

I am coming back to modelling after a very long break away and would like some advice. First, let me say that DCC is the best thing that has happened to modelling while I have been away and to have a fully DCC operated layout is the end goal. The main challenge for me is that I have 30+ DC locomotives and even after thinking hard about how many of them I would need to replace with up-to-date DCC models to run the layout I am planning, I'm still over the 20 mark and that's not an investment (lottery winning aside) that I can make in a short time frame. I have read some of the comments about converting from DC to DCC and I agree that it's not really worth the effort.

 

So, based on the fact that I want to 'get trains running' sooner rather than later, I am planning on building the layout to support old-school DC operation which clearly means track isolation and switches etc. and then when the roster of DCC engines reaches that critical mass convert over. The simple question is, could that just involve making all the sections permanently live (just switch everything on) and re-direct power from DC to DCC controller? But I guess the more specific question is if there are any tips and tricks that I can adopt at this point which will make that transition much easier, in particular about choice of points (insulated v live) and the installation of point motors for them.

 

Thanks in advance...

[Oldddudders]

The conventional wisdom is that DC and DCC layouts need the exact same wiring - but the DCC layout doesn't need the section switches, so your ideas are right. Switching all sections to the DCC input is what I did more than 20 years ago to implement DCC for the first time. Do be bothered to add a soldered conductor to every piece of rail - rail-joiners can and do cease to conduct in some cases, leaving you with a dead section. 

 

Live-frog points with a separate switched feed to the frog, rather than relying on rail-to-rail contact, certainly help - with both DC and DCC. 

 

Do not be tempted to have part of the layout able to be DC or DCC at the throw of a switch. There is a great risk of a loco or vehicle bridging some gap so you send DC into your DCC system, probably reducing it to junk instantly. Disconnect completely one power system before attaching the other. 

 

Some DCC systems allow you to run one DC loco, but the excruciating sound from the poor motor should tell you it isn't happy, so if your chosen system allows this, don't run the loco for more than a few seconds, e.g. to check it runs in both directions etc. . 

 

Yes, getting DCC into a layout costs, but the operational benefits for all but the smallest, simplest layouts are worthwhile. 

[Dungrange]

40 minutes ago, AndyRAP said:

So, based on the fact that I want to 'get trains running' sooner rather than later, I am planning on building the layout to support old-school DC operation which clearly means track isolation and switches etc. and then when the roster of DCC engines reaches that critical mass convert over. The simple question is, could that just involve making all the sections permanently live (just switch everything on) and re-direct power from DC to DCC controller? But I guess the more specific question is if there are any tips and tricks that I can adopt at this point which will make that transition much easier, in particular about choice of points (insulated v live) and the installation of point motors for them.

 

Yes, that would seem to be the best way forward.  Effectively you wire for DC Cab control and then when you are ready to switch, set all section switches to one position and plug your DCC command station in instead of the previous DC controller (making sure that you then remove the other DC controller positions so that you can't inadvertently mix DC and DCC).  I think that the only thing you need to do specifically is use wires with a cross section that are suitable for carrying DCC currents (> 5 Amp) with minimal voltage drop, rather than trying to get away with small cross section wires that are used on many DC layouts on the basis that most DC controllers can't put out more than 1 Amp.

 

As for the points and point motors, that's up to you.  There is no such thing as 'wiring for DCC', there is just good wiring practise and less good wiring practise.  DCC effectively requires that you adopt good practise because the short circuit breakers in a DCC system shut down much faster than a DC controller.  Therefore wire each section with its own feed. 

[34theletterbetweenB&D]

Heretic here.  A properly wired common return 2 or more cabs controlled layout can very easily be used to run DC and DCC simultaneously - very handy indeed if you are minded to test run mechanisms on DC ahead of DCC decoder fitting - subject to having a suitable track layout, and a practised operating discipline. It's no more difficult operationally than mirror, signal, manoeuvre; so just a drill to follow to ensure no loco can run over any DC/DCC boundary.

[Dungrange]

28 minutes ago, 34theletterbetweenB&D said:

Heretic here.  A properly wired common return 2 or more cabs controlled layout can very easily be used to run DC and DCC simultaneously - very handy indeed if you are minded to test run mechanisms on DC ahead of DCC decoder fitting - subject to having a suitable track layout, and a practised operating discipline. It's no more difficult operationally than mirror, signal, manoeuvre; so just a drill to follow to ensure no loco can run over any DC/DCC boundary.

 

I agree that it is possible to construct a dual DC / DCC layout, but I would dispute the words highlighted in bold.  You can't have your DC and DCC system sharing a common return.  If you really want to have dual DC and DCC cab control with both systems live at the same time, then I think you need switched feeds and switched returns for each section, not a common return.  I agree that it is then possible to run DC and DCC locomotives simultaneously provided you have a rigorous operating procedure that ensures that the two separate control systems will never come into contact.  However, it is so easy to inadvertently throw the wrong switch or for something to derail and cause a short with the possible consequence of writing off hundreds of pounds worth of electronics that I and most people don't think its worth taking the chance.

 

Therefore if anyone new to the hobby asks for advice, I would advise against mixing DC and DCC unless you really know what you are doing, understand the risks and are prepared to take these risks.

[34theletterbetweenB&D]

2 minutes ago, Dungrange said:

I agree that it is possible to construct a dual DC / DCC layout, but I would dispute the words highlighted in bold.  You can't have your DC and DCC system sharing a common return...

Of course you can, the electrons know exactly where they have to go! The very same principle on which cab control is based and long proven that keeps two or more DC circuits each powered from independent transformer secondaries functioning independently; will keep DC and DCC inputs similarly running off separate transformer seocndaries fully independent.

 

Granted, the layout constructor has to understand the principle and follow it scrupulously. But to say 'cannot be done' is akin to saying that because some people drown, no swimming.

[sb67]

All good advice AndyRAP. On my layouts, small layouts admitedly, I've used electrofrog points, wire droppers on every piece of track and with isolating sections. I operate on DC or DCC, when on DCC just make sure all the sections are on. I've learnt that using  either power source the wiring should be generally the same, the only thing not needed with pure DCC are sections. 

In your case I would wire thoroghly for DC then just leave any sections on when you go for DCC. Personaly I wouldn't mix them though.

 

Steve.

[Izzy]

As has been said I also ‘converted’ my layout by leaving all the section switches on and plugging in the DCC command station instead of the DC one. I still use, as then, 5-din plugs sockets so it’s easy to do. I could not contemplate trying to run DC/DCC together, but then my layouts are small. Although my layouts are now wired without sections I can still plug DC in to test a loco for running qualities on the track/points should I choose. However this is easy since I don’t have locos sitting permanently on the layout/s I have.

 

As many do I also still control my points and signals manually the old fashioned way, just the same as before, and all powered separately but from the DCC output ( possible because it’s a 3.5amp system).
 

In fact you can keep control either separately or through the DCC system, but this is an area where you need to decide the actual DCC system at the beginning, as it’s either not possible or isn’t as easy with some as with others. 

 

Izzy

[JimFin]

On 23/11/2019 at 10:42, AndyRAP said:

and the installation of point motors for them.

 

For that specific issue, you could consider using ESU Servo Pilot accessory controllers and have servo operated points (and signals?). The Servo Pilot allows hard wiring of switches for DC operation via a mimic board or whatever method you choose but equally, maybe at a later date, be converted to DCC by simply plugging in the DCC controller. I have used these devices successfully in both configurations. 

[Phil S]

A consideration NOT MENTIONED in any of the answers above is related to your eventual choice of DCC Control System... What Current Capacity does it have as its NORMAL MAXIMUM  ( there will then be a higher current at which the controller then trips to protect itself.

 

Whilst you may be looking at a 'DCC Starter System with a limited output of only 1A ... ie about the same as your notional analogue controller ... you are more likely to choose a system with 3.2 A, 4A or 5Amps as the normal maximum rating    ( Using European as opposed to US examples, that is Roco Z/z21, Hornby Elite, or ESU console for common examples )

 

YOU NEED TO ENSURE that YOUR wiring can CONDUCT continuously that rated current, without producing an unacceptable voltage drop at any part of the layout, AND that a SHORT CIRCUIT occuring in any part of the layout ALLOWS SUFFICIENT CURRENT to flow, to ensure that the Controller cuts out immediately.

 

Wiring that may have been sufficient for Analogue or a LOW POWER DCC system MAY NOT Be sufficient to offer the REQUIRED level of protecton if a MORE POWERFUL controller (or Boosted output)  is used !!

[This hight-current requirement can be reduced, in the smae way that houselhold mains electrical circuits offer different levels of protection by having  'fused' circuits  ....

in the case of mains electricity, typicallly 30A (Ring Main)  and 5 Amp (lighting)  ..... or for the DCC layout:    FULL OUTPUT [ or a bit more than needed for your point motors]  for the ACCESSORY BUS,  and then PSX intellignet circuit breakers or NCE PB1/3 circuit breakers  for the track buss(es)    .... so that THEY provide the protection at LOWER LEVELS than the TOTAL output of the powerful Dcc control systtem.    [ Yout house probably has a 100A 'company fuse', but lots of 30A, 15A and 5A circuit breakers for individual areas - for the same reasoning: PROTECTION.  

 

[Crosland]

YOU NEED TO ENSURE that YOUR wiring can CONDUCT continuously that rated current, without producing an unacceptable voltage drop at any part of the layout,

 

He wants to start out by building the layout for DC. That implies lots of sections with individual feeds. When all the section switches are set to ON and connected to the DCC boster there will be multiple parallel feeds to the layout. Under normal operation, no individual section wiring will ever draw the full continuous current that he booster can supply. Planty of layouts have been successfully converted this way.

 

If starting from scratch, going directly to DCC, then things would be different.

 

 

[Phil S]

"He wants to start out by building the layout for DC. That implies lots of sections with individual feeds. When all the section switches are set to ON and connected to the DCC boster there will be multiple parallel feeds to the layout. Under normal operation, no individual section wiring will ever draw the full continuous current that he booster can supply. Planty of layouts have been successfully converted this way.

 

If starting from scratch, going directly to DCC, then things would be different."?

 

Phil: This is WRONG as their will still be ALL the INSULATING FISHPLTES in place making the feed to EACH SECTION INDEPENDANT !!!!!!

ONLY when a loco bridges a section will the current be shared between ( the two ) adjacent sections !!!!!

The SHORT CIRCUIT TEST should still be tested in EACH section.  Or the protection is not there.

After adoption of DCC multiple locos and lighting/ sound loads  may occur within a single 'analogue' section.

 

 

[Junctionmad]

Short circuit protection is being over emphasised. Even light wiring , ie 7/0.2 has low enough resistivity to allow booster trip currents to flow. If there is any issue it’s in the wire to track or track to track connections in my experience 

 

it’s hard to do it incorrectly in reality  

Edited November 25, 2019 by Junctionmad

[Crosland]

7 hours ago, Phil S said:

"He wants to start out by building the layout for DC. That implies lots of sections with individual feeds. When all the section switches are set to ON and connected to the DCC boster there will be multiple parallel feeds to the layout. Under normal operation, no individual section wiring will ever draw the full continuous current that he booster can supply. Planty of layouts have been successfully converted this way.

 

If starting from scratch, going directly to DCC, then things would be different."?

 

Phil: This is WRONG as their will still be ALL the INSULATING FISHPLTES in place making the feed to EACH SECTION INDEPENDANT !!!!!!

ONLY when a loco bridges a section will the current be shared between ( the two ) adjacent sections !!!!!

The SHORT CIRCUIT TEST should still be tested in EACH section.  Or the protection is not there.

After adoption of DCC multiple locos and lighting/ sound loads  may occur within a single 'analogue' section.

 

Please RE-READ what I WROTE, and the CONTEXT that I quoted.

 

It's BECAUSE each section is independent that they will NEVER, UNDER NORMAL OPERATION, see the full sustained booster current. There will simply never be enough locos in ONE section to draw the full booster current. DC style section wiring to each section WILL be adequate.

 

I NEVER questioned the need for a short test in each section. If that fails THEN upgrade the wiring to that section.

Edited November 25, 2019 by Crosland

[Crosland]

30 minutes ago, Junctionmad said:

Short circuit protection is being over emphasised. Even light wiring , ie 7/0.2 has low enough resistivity to allow booster trip currents to flow. If there is any issue it’s in the wire to track or track to track connections in my experience 

 

it’s hard to do it incorrectly in reality  

 

I've seen it done, for exactly the kind of reasons you mention  Large-ish setrack layout with a single power clip feed.

[Phil S]

Please Reread THE CONTEXT IN WHICh i WROTE IT TOO !!   .... iT WAS TO BE CONSIDERED AND CHECKED  .. IF A HIGHER OUTPUT CONTROLLER WAS PURCHASED (such as 3A-5A quoted) replacing the 1A or less of the original analogue.   

 

The short circuit current is higher than the maximum normal output - and therefore requires a lower loop resistance to be achieved than would be required to maintain the full current with only a few volts drop, and loco load in series.    it is then, hopefully , only momentary, and so heat build up is not a problem.

 

Really it becomes the only safe rule about layout wiring  - is it low enough resistance to ensure the chosen controller can trip. .... and that depends on your controller's output.

 

You appear to be overlooking the simple fact that each 'analogue section' would still exist in the 'converted layout' -- the switches are likely to be at the controller end, and thereofore each section is being fed by its single run of cable  - without the benefit of a larger bus.   A short circuit could occur in ANY section - and the controller should cut out, and not continue to supply the (maximum+) current ad infinitum.     

 

And the bigger the controller's output, the greater the problem   (unless you use something like a PSX to limit the track current - which would be an effective solution.

[Junctionmad]

Quote

The short circuit current is higher than the maximum normal output

Absolutely it should be checked, but Ive not seen a single case of where DC wiring wasn't sufficient to trip the booster.  Its only in very unfortunate situations where bad connections are made that I've seen anything like the issue 

 

its not quite a big deal as you say , checked yes , but lets not loose our shirt over it. 

[Crosland]

On 24/11/2019 at 18:49, Phil S said:

YOU NEED TO ENSURE that YOUR wiring can CONDUCT continuously that rated current, without producing an unacceptable voltage drop at any part of the layout reasoning: PROTECTION.  

 

 

There's the quote again. It has ABSOLUTELY NOTHING to do with short circuits. All I said was that normal DC wiring will be adequate for the continuous booster current, UNDER NORMAL OPERATION. Again, nothing to do with short circuits. I DID NOT say anything to refute your statements about testing the short detection.

 

You can have the last word, Just don't twist my words to fit your own agenda.

 

[AndyRAP]

Hi All...

 

Thanks for the feedback. In general, it looks like I am going about this in a reasonably sane way! I may even share the layout plan shortly to see what thoughts the community have on it.

[ahellary]

ok one thing that hasnt been touched on is ..... if your going dcc in the future then are you going the next step and introducing computer control if you are then you should think about needing train detection ... that then opens up a whole can of worms ... as you will need to have blocks of track so that the detector can sense a train in the block which is mostly done by detecting a current dreaw in the section of trach you can do train detection others ways to but the best is current detection... so if you have a terminus you may actually want 2 or even 3 sensors in the platform ... one at the each end then the main platform as well ... the one at the far end is so that you can stop the train accurately the main one is so you the computer knows theres a train there and the entrance one is so the computer can see another loco joining onto the coaches to wiskthem away be it to the carrage sidings or to haul them off to london

 

just my thourghts as some people (yep me) do that sort of thing

Edited December 2, 2019 by ahellary