Last Updated: 19 May 2023

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.

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:

• 16 AWG – 1,5 mm² – accessories
• 14 AWG – 2,5 mm² – track
• 12 AWG – 4 mm² – track

The 14 AWG recommendation is probably fine for track outdoors. Of course, 12 AWG is even better, but its size and inflexibility may make it annoying to work with.

Bus Feeder Wire Sizes

I found no general guidelines, but I did investigate some stuff I own:

• 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.