Wiring Questions from a Novice

Model Railroader Electronics and DCC
1

Hi,

I am in the process of building my first permanent layout and I have decided to use DCC. I have already purchased a Digitrax Super Chief and plan to use radio control. My layout is 19’x23’ with a 10’ peninsula “around the room” layout for continuous running. I have also purchased the wire for the track bus and feeders and am about ready to install. However, this process quite frankly scares the wits out of me, because I know next to nothing about wiring and electricity. But I want to do it right so that my layout runs smoothly. So I need help. I have searched this and other forums for information but I’m a bit confused.

  1. Do I run just one set of bus wires continuously around the room, or do they need to be divided into sections for multiple power districts?

  2. What do I do with the end of the wire furthest from the controller?

  3. Does the bus connect directly with my Digitrax system?

  4. I’ve seen some mention of using ordinary light bulbs to isolate shorts. How does that work? Do you recommend this?

I apologize - I know for most of you that these questions are elementary and they have probably already been addressed. But, as I said, the more I read the more confused I’ve become. Thank you in advance for your help - and for those who do answer my questions, assume I know nothing about wiring…and you’ll be correct. :slight_smile:

Pierce

2

Pierce,

I’m replying (I’m not a regular poster) because I was in exactly the same position as you. I bought a Digitrax Zephyr some time ago and knew nothing about wiring, electricity, digital control and this was my first layout, so I know where you’re at.

  1. You can have one set of bus wires go around the room if you like. More advanced readers here have implemented dividing their power supply and wiring into power districts. It is far simpler to initially have a set of bus wires.

I bought lengths of 14 gauge RED and 14 gauge BLACK wire for my power bus. I picked one rail to be the left rail and one rail to be the right. I dedicated Black wire to supply the left rail and RED to supply the right rail. I ran this wire underneath my layout directly under the rails. I purchased 18 gauge separate strands of Red and Black wire to connect my rails to the bus wires. I soldered (do you know how to solder - a useful skill!) pieces of the 18 gauge wire from the track down to the bus wire underneath (every 3 feet or so on the track).

  1. Nothing. The bus wires do not have to be capped or run in a continuous loop or anything like that.

  2. Yes. Your Digitrax system has several connections. The connections marked TRK A and TRK B are to be connected to your black and red bus wires. Please refer to your Digitrax documentation. It provides a pretty good explanation.

  3. I’ve read about it but not used this technique. No opinion, really.

We’ll help you out!

Dave

Note that I do NOT have a reversing loop in my track.

3

Pierce,

I may have a bit more experience than you and Dave but I am certainly no expert. First, I would encourage you to take a look at two web sites: 1. DCC for Dummies (http://www.members.optusnet.com.au/nswmn2/DCC.htm) and 2. Wiring for DCC (http://www.wiringfordcc.com/). Both sites are rich resources for DCC info. The DCC for Dummies site contains a discussion of using auto lamps for short detection.

I respectfully disagree with Dave’s statement that “It is far simpler to initially have a set of bus wires.” Simpler initially, yes, but more complicated/difficult in the long run. For a layout the size you describe I would strongly recommend segmenting the layout into a few electrically isolated sections (commonly called power districts). This will make troubleshooting much easier since you will only have to look for a problem in one section rather than the whole layout. And if there is a short, it will only shut down the section in which the short occurs. And going back later to retrofit power districts will not be simple.

With regard to your third question, if you do set up power districts, you would have the two track output wires go from your command station to some sort of electrical panel where the power would be distributed through a circuit breaker for each power district. (If I knew how to attach a photo to this post I would show you my panel.) Then two bus wires would leave each dircuit breaker and run under the tracks for the respective power district.

Good luck!

4

I’m a DCC newbie with a question regarding circuit breakers. What rating should these breakers be? Does someone make a circuit breaker panel specifically for DCC? My layout is much smaller (7X4 HO). Do I really need to do this or should I just run 2 wires to the track?

Not trying to hijack the thread!

Thanks

Todd

5

Thanks for the excellent advice.

How do I separate the bus wires into sections?

Pierce

6

Pierce, probably good to do some additional reading first. Power districts are electrically isolated areas of not only the bus but of the track. There are typically additional components involved such as boosters and district managers (take a look at the Digitrax site since you have their products) which are configured in such a way as to supply power to all sections of the track and if there is a short in one section, power is not interrupted to the other sections.

Anyway, best for me not to add anything more in this area because I don’t have the experience. Others can probably give you a better explanation.

Dave

7

Pierce,
I’m a 10-year Digitrax DCC user, and I’ve wired both my home (25’ x 50’) and my club (1/3rd of an eventual 6300 sq. ft.) layout. Electrically, my club layout is as complicated as can be, while my home layout is as simple as can be.

For starters, let’s be clear that there are two busses used, one for track power and one for throttles and accessories (which is essentially 6-wire phone cable). This is all about the track bus, which should probably be around 14AWG.

1). On my home layout, I have a 200’ long mainline. I ran 200’ of 14AWG red and black wire under the main, and dropped feeders every 9 feet. I have no circuit breakers, no extra boosters (I’m using a Zephyr system only), and no extra wires. The downside is that if there’s a short anywhere on the layout, everyone knows because all the trains stop. However, that’s not so bad because it lets everyone know that someone messed up, so it can be a lot of fun, too.

At my club, we have 8 boosters and 36 or so Power Shield circuit breakers. We have it set up so that each breaker protects 4 blocks (and each block is approx. 15’ long), and each booster powers approx. 4 or 5 breakers. Usually, a short only effects the small area around the derailment, and most people don’t know if something is awry.

2). Nothing, although some folks like adding a filter to help reduce noise on the bus. However, this is nothing one should worry about unless one starts to have problems.

3). Yes, of course. The Rail A and Rail B (we use B = Black, A = Red) connectors on the front of your DCS100 tie directly into the track bus.

4). I would not recommend using lightbulbs for circuit protection. We found that they caused too much drain on the system. We quickly switched to PowerShields and have used these exclusively every since.

8

Here’s my view on the subject. [:)]

1. Do I run just one set of bus wires continuously around the room, or do they need to be divided into sections for multiple power districts?

It’s more about how much load current your layout will need to provide, and where? This is determined by the number and type of locos and rolling stock you operate at one time.

On my similar sized layout my booster

9

This is why most people recommend starting something small and working with it until they understand it.

Depends on the layout and what you are trying to accomplish with it. Things like - are there locomotive facilities where lots of locomotives will be sitting around, are there large yards, how many operators, how many simultaneous trains, how many industrial areas with simultaneous switching, etc. NEED is probably the operative word here. No it does not NEED to be, but I am guessing there are several reasons one would WANT to.

Which wire. There are probably going to be three. The DCC power bus, the DCC throttle bus, and the DCC control bus (runs from the main controller to all the boosters - if any).

Yes on all three counts.

There have been whole threads on this topic. If they have been read as you indicated and don’t understand it from them, anything we add here will not help.

So, as I’ve said, start with something much smaller than your whole layout. Start trying to apply what you are reading. When you come across something that doesn’t seem to work, re-read with the new knowledge of your application and it might make more sense. Ask specific questions, re-try, re-read, repe