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Installing the Track Power Buss
Getting sufficient "juice" to the tracks is important for successful operation with DCC.  Key to that success is what I call the "track power buss".  This is simply two wires that run underneath the module from one end of the module to the other.  At each end, you wire in your favourite connector plugs so that you can easily connect the track power buss to the next module.  Here's a picture of what we're talking about. 
This is one half of the bottom side of my Irondale module.  I've run two 14 AWG wires - one yellow and one red - from one end of the module to the other.  This forms our "track buss".  At each end, I've soldered in a 2-wire trailer connector - because that's the standard for the module railroad club I belong to.  From here, the trailer connector will connect to the next module to pass the "juice" along to the next module, or it will be connected to my command station/booster. 

You can see two sets of yellow and red wires that are hanging loose that I've labelled "pigtails".  These are simply a piece of 18 AWG yellow wire and a piece of red wire that I soldered and shrink-wrapped to each of the corresponding track buss wires.  I usually install the pigtails about every two feet along the track buss. The pigtails make it easier to solder the track feeds to rather than trying to solder them to the track power buss that has been snugged against the underside of the styrofoam

I've fabricated the buss wire/pigtails at the workbench and installed them on the bottom side of the module using some wire staples to hold everything in place. 
The Tools

You can also see some of the tools I use.  From left-to-right: 
  • Drill with a 6" piece of coat-hanger with the end filed flat (there's also a 1/8" drill bit in the picture.   We'll use this to drill holes through the roadbed and styrofoam and then thread our track feeds through these holes. 
  • 40 watt pencil soldering iron.  We'll use this to solder track feeds to the rails and to the pigtails. 
  • Pair of cutters and pliers (just barely visible) to cut and strip the insulation from the ends of the wire. 
  • 100/140 watt soldering gun - the first click on the trigger produces 100 watts of heat and the second click produces 140 watts of heat.  We'll use this in those cases where the 40 watt soldering iron can't produce enough heat to melt the solder so that it flows into the wires. Typically, the 18 AWG pigtails and the 14 AWG track power buss need to be soldered with the soldering gun as the 40 watt soldering iron doesn't produce enough heat. 
  • Resin core solder flux is in the white jar.  We apply this to each joint we're going to solder before we apply the soldering iron and the solder. 
  • Resin core solder is barely visible on the edge.  It's very important that you use resin core solder and flux.  Don't use acid-core (sometimes called plumber's) solder and flux!  That will ruin your soldering iron and will corrode the wires. 

Wire Thickness - AWG
Because DCC uses a high voltage and amperage compared to analog or DC operations, the thickness of the track buss wire is most important.  In North America, this thickness is specified in terms of AWG - American Wire Gauge.  With AWG, the higher the number, the thinner is the wire.  For example, 24 AWG wire has a cross sectional thickness of 0.20 square mm whereas 14 AWG wire has a cross sectional thickness of 2.08 square mm - a difference by a factor of 10.  This means that more "juice" is able to flow down 14 AWG wire than 24 AWG wire. 
American Wire Gauge (AWG)
. Outside Diameter . Cross Section
AWG Inches mm . Sq In Sq mm
10 0.100 2.59 . 0.0082 5.26
12 0.080 2.05 . 0.0051 3.31
14 0.060 1.63 . 0.0032 2.08
16 0.050 1.29 . 0.0020 1.31
18 0.040 1.02 . 0.0013 0.82
20 0.032 0.81 . 0.0008 0.52
22 0.025 0.64 . 0.0005 0.32
24 0.020 0.51 . 0.0003 0.20

Your DCC operating manual typically specifies a minimum wire size of 16 AWG for the track power buss.  Current wisdom on DCC discussion forums advocates a minimum of 14 and even 12 AWG.  This is a case where bigger is definitely better. 
You might be used to using colour-coded telephone wire for your analog operations.  This is typically 24 AWG wire.  Take all of this wire and junk it!  It won't do!  Even for track feeders.  This thickness is 1/10th the cross section of 14 AWG wire.  With DCC, we're pumping 16 volts and 5 amps into the tracks at all times.  Anything that impedes the flow of this current into the tracks will reduce the effectiveness of your DCC system. 
Installing Track Feeds

Once the track power buss with the pigtails has been installed on the underside of the module, the next step is to install track feeds.  I like to colour code my wiring.  In this case, I've cut about a dozen pairs of 20 AWG stranded wire.  I use a wire with a white insulation for the bottom rail and a red insulation for the top rail.  I've stripped and tinned about 1/4" of each wire, then bent the wire so that it fits snugly alongside the track.  I've drilled holes on the outside of each rail through the roadbed and styrofoam.  I next threaded each wire through it's respective hole and soldered the bent part of the wire to it's respective track.  
Here's a schematic of what I've done.  

But we're getting ahead of ourselves.  The photo below shows the installed track feeds soldered to their respective rail and hanging below the underside of the module. All we need to do now is solder the track feeds to the ends of the closest pigtails. 

Soldering the Track Feeds to the Pigtails
The next step is to gather the track feeds to the nearest pigtail, cut strip, solder and shrink-tube the track feeds to their respective pigtail.  In the photo below, we've gathered the red track feeds to one of the red pigtails and the white track feeds to the yellow pigtail (because that's the colour scheme I wanted to follow). 

Here's another photo which shows things a bit more clearly. 

And this is what the final job looks like.  From start to finish, it took me about 30 minutes to fabricate the track power buss and pigtails, and an hour to install the 12 pairs of track feeds and connect them to the pigtails. 
And that's all there is to wiring for DCC!
On the next page, we'll show you some tips for wiring turnouts. 
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