Large Scale Wire Size

Last Updated: 16 February 2022


Introduction

Wire sizes are important, yet I found it very confusing to know what sizes I should use. So I had to do some research, which I’ve summarized for myself below.

Most importantly, there are two different ways to describe a certain wire diameter: the AWG (American Wire Gauge) standard, and a metric approach described in mm². You can find a conversion table below. Bottom line: the higher the AWG number, the smaller the wire diameter is.

AWG American Wire Gauge Conversion Table
Image Source: https://www.elmec.com.au

So what sizes to use for G Scale / Large Scale? To me there are two different requirements: track feeder wires (indoors and outdoors), and bus wires (e.g DCC wiring inside a locomotive).

Track Feeder Wires Sizes

After some research, I generally found the following recommendations:

  • 14 AWG – 2,5 mm² minimum
  • 10 AWG – 4 mm² maximum

The 10 AWG recommendation would be most suited for outdoors, and is potentially overkill, but the rigidity is a bonus in an outdoor environment. Of course, it’s a good idea to stick with a larger diameter for a longer wire section.

I prefer stranded wire because it’s more flexible, and the ends can easily be soldered to make them easier to work with.

Bus Feeder Wire Sizes

I found no general guidelines, so I based my “decision” on some examples I found.

  • PIKO uses 24 or 26 AWG wire in their locomotives for track power pick-up, motor connections, and lighting.
  • PIKO has a small 1 Amp transformer set which comes with a 18 AWG wire pair to connect the power supply (20 V AC, 28 VA) to the controller (0-20 V DC, 1 A).
  • I saw that an American company who provides electrical accessories for rolling stock uses 24 AWG and 26 AWG for their products.

… so I decided to go with 24 AWG for internal rolling stock connections, either for DC or DCC. At this size, I prefer solid wire instead of stranded wire to make connections easier.


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