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Layout Wiring – Standardizing

 Standardize your Layout Wiring

While every layout can be wired in many different ways, there are numerous advantages to standardizing some elements of your wiring.

By opting to follow some Best practices, you can avoid potential electrical issue. Wiring issues on Smaller layouts are less of an issue, but can still derive advantage from some level of standardization.

By planning ahead and taking an engineering point of view to the wiring design as well as an operation point of view, you will know the large layout will work reliably from the start and maintain a high level of reliability over its entire operating life.  This applies to both large fixed layouts and modular layouts

Wiring for Larger Layouts

While there are numerous similarity in wiring small and large layouts, there are a number of potential electrical issues that can be encountered when using DCC on a large layout (which small layouts typically do not encounter)

What is a large Layout?
While I am not aware of any official definitions in this regard, it is commonly accepted that a Large Layout is any layout that is larger than a typical 2 car garage (30 m2 / 300 Sq Ft).  Most club layouts in the UK are larger than 30 square meters, whereas club layouts in other countries vary).

Other things that Large Layouts tend to need:

  • long bus runs (Cab Bus, Booster/Control Bus and Track Bus)
  • more power (current) to run more trains
  • power management using “DCC Circuit Breakers” to create “Power Districts” to control short circuit issues
  • a Track Bus with large gauge wire to carry the high current over long distances with minimal voltage drop
Such layouts can start to have track bus wire runs longer than 9m (30Ft) which is the beginning point at which problems can start to appear.
Some modellers claim they have long bus runs and have no problems.  The problem with such statements is:
  • Each Layout is wired differently.  The quality of the wire and installation will vary greatly along with the routing and bundling (intentional or not) of various wires together.  It is as unique as the individual who built it
  • Most people do NOT know what to look for in terms of potential electrical problems.
  • If it runs, it must be OK….wrong!
By planning ahead and taking an engineering point of view to the wiring design as well as an operation point of view, you will know the large layout will work reliably from the start and maintain a high level of reliability over its entire operating life.  This applies to both large fixed layouts and modular layouts

ANECDOTAL WIRING ENGINEERING does Not equal Good engineering

Many DCC list always have people often citing “anecdotal evidence” that DCC wiring can be done this way or that way.  This leads to layout design decisions that are Anecdotal Engineering based.

“Hey I wired my layout this way and it worked!”  The hidden assumption is that DCC wiring is a go or no-go situation and since this wiring worked it must be a go.   The ends justified the wiring means thinking.

Collectively the wide range of different anecdotal comments comes across to the other listeners like it does not matter how you wire you layout.  At the same time it does not help them because the person who may be asking how to do the layout wiring is not given a clear answer that will give the best results.  Instead they must choose among opinions and use their own experience to guide them.

Anecdotal comments in layout wiring are easily believed because the experience with wiring DC layouts was not so critical.

This does turn out to be true for small DCC layouts, the 4’x8′ plywood layout is the most common, simply because there is not enough wire length or poor wiring quality to really get yourself into any type of electrical trouble.

Indirectly supporting that “does not matter” position is the DCC industry simply because they do not want to scare away the customers.  It is not in their interest to talk about wiring especially since MOST of the customers will not have any problems….the small layout customers.

However this anything goes wiring belief starts to fall apart with large layouts using DCC.

One of the big sources of error in anecdotal wiring advice is the FACT that no two layout are the same size nor wired exactly the same.

The wiring is as unique as a finger print.   Wire type, wire gauge, wire routing, wire bundling, wire connection quality.

The same is true about the engines running on the layout, the power levels involved and the different DCC systems involved.

Hence even the operations level expected of the layout is also as unique as a finger print.

In other words there are way to many variable involved such that there is no way one can guarantee the anecdotal suggested wiring system will work for your large layout.

Just like a house, a layout is only as strong as the foundation that it is built upon.  In this case we are talking about the electrical foundation of the layout…the DCC wiring.  The wiring a large layout has a lot more design considerations that need to be taken into account than that of a small layout.

The quality and consistency of the wiring needs to be raised to account for the potential problems that one can encounter up front in the wiring design process.

Some DCC vendors have started to recognize this and added comments about large layout wiring in the manuals.

It has been said:  “Quality of product is the result of knowing and anticipating how the all of the different types of user will actually expect to use the product.”  These goal can be met by implementing a WIRING STANDARD for the layout that is based on good engineering and operational practices.  The wiring standard will consist of (not in any order):
2) Consistent high quality installation.
3) Easy Of Trouble Shooting.
4) Flexible Installation.
5) Takes into account the properties of the wires to maintain maximum DCC signal fidelity.
6) Takes into account the properties of the wires to minimizing known electrical problems.
7) Controlling the effects of short circuits on the rest of the layout.
 Item #1 deals with standardizing the wire and the connection system used with the wiring.  By using just a few wire sizes and connectors the allows the inventory of unique wiring supplies to be small and allow bulk purchasing to lower the overall cost.

Item #2 deal with using the right tools and test equipment use to make consistent high quality wire assemblies.

Item #3 mean that with a standard way of wiring things, you will always know what wire does what when you get under the layout.  Less guesswork and quicker problem solving.

Item #4 means a wiring system that is flexible in adapting to the local track wire requirements before you know what the final track plan may be.  It also related to Item #7.

Item #5 and 6 deal directly deals with the properties of wiring related to DCC.  See Track & Wire Properties

Item #7 involve the partitioning of the DCC power such that a short circuit will have minimal effect on other operators on the layout.
Layout wiring can be divided into two areas: Control wiring and power wiring.
Control wiring at a minimum is concerned about Throttle and Cab wiring.  But it can be expanded and include control panel wiring.
Power Wiring at a minimum is concerned about the wiring to the track itself.  But it can include power for accessory devices that are to be controlled by DCC.
Below is a list of various wiring topics that deal with these concerns in both of these categories.  Click on each catagory to learn more:
Control Wiring
  • Command Station Needs
  • Cab Bus Wiring
  • Control Panel Wiring
  • Accessory Wiring
  • Occupancy Detection Wiring
Power Wiring
  • Boosters Power Needs
  • Booster/Power District Wiring
  • Accessory Power Needs
  • Occupancy detection Wiring


Article Credit: Mark Gurries, Wiring for DCC

Posted in DCC
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