Using the correct model rail wire is essential in making the wiring of model railroads easier and cheaper. But which is the most suitable type of wire size to use?

This guide aims to provide an overview of the best wire for model railways in addition to covering the O gauge wiring gauges and 00 gauges wire types needed to build safe and robust electrics on model train layouts.

Wire Sizes for Model Train Layouts

In addition to the wire itself, switches, sockets, connectors and heat shrink tubing may be required to accomplish the final result. Be sure to consider this when budgeting for your model train layout materials as these tend to mount up over time, particularly on larger layouts.

Summary of bus and dropper wire sizes

Bus Wires
Small Layouts Medium Layouts Large Layouts
1.29mm diameter – 18 gauge 1.62mm diameter – 16 gauge 2.5mm diameter – 14 gauge
Dropper Wires
0.64mm – 23 gauge

Individual types and gauges of wire behave differently when being shaped, bent and soldered. Choosing the wrong wire gauge can make simple wiring tasks more difficult and problematic than they need to be.

Be sure to get a good quality wire stripper that allows for easy removal of the outer insulating tubing - this can become a laborious task on larger layouts or if you're doing a lot of wiring.

Perhaps the greatest problem often encountered when wiring a model railroad layout is the use of the wrong wire size. This can create electrical issues around the layout meaning insufficient current being passed through the track to your model trains. This can lead to erratic running, juddering or stalling of locomotives. See our guide on why model trains run slow for more information for existing layouts.

Therefore, choosing the correct wire size for your model railroad electrics is a key part of building the best train layout possible - it also makes the build process cheaper and easier resulting in a more reliable and trouble-free experience.

Bus wiring sizes for model railroad track

In terms of bus wiring there's three sizes that are recommended depending on the overall size of the model train layout that you're building.

  • 1.29mm diameter – 18 gauge
    For small layouts 8'' x 4'' and below.
  • 1.62mm diameter – 16 gauge
    For medium-sized layouts up to 12'' x 16''
  • 2.5mm diameter – 14 gauge
    For large layouts above 12'' x 16''

Best wire for track feeders and dropper wires

Track feeders and dropper wires should only be a few inches in length, so smaller gauges are more than adequate here. 0.64mm diameter (23 gauge) should be ideal.

The advantage of using smaller gauge wiring for the track feeders and droppers is that it's a lot easier to work with during model rail soldering.

It's possible to use larger gauges of wire than recommended (e.g. 14 gauge for smaller layouts). However, remember that you'll need to connect or solder these wires to small contacts. For example, it can be difficult soldering thicker grade wire to small rails. So, ideally you'll want to stick to the recommended gauges above.

Solid vs Stranded Wire for Model Railroads

There's often large discussion among the model train community around whether solid or stranded wire is better for model railroad electrics. Some modellers champion stranded wire, claiming that it's easier to work with and more tolerant to being bent around tight corners, such as those commonly found on most baseboards. Others argue that solid wire is easier to solder, particularly to rails.

Solid core is best for straight wire runs, whereas stranded is better for wire that needs to bend, twist or frequently move.

A good rule for model railroad electric design is that if you've got a fairly straight wire run that won't move then solid core is best. However, for any wire runs that will be bent, twisted or frequently moving then stranded wire is best.

The reason behind this is that stranded wire is more flexible, allowing it to be more easily bent or manipulated from straight. Solid core wire is generally more likely to break under these conditions.

Solid is usually cheaper to purchase, however if your budget allows it can be well worth using stranded wire for all wire runs - this will significantly reduce the chance of breakage, given the increased flexibility.

What Color Wire to Use for Model Railroad Wiring

Many beginner railroad modellers often ask whether they should use a specific colored wire when wiring their model train layout.

Simply put, you can use any colored wire that you want.

The color of the outer insulation on the wire has no bearing on the electrical or physical characteristics of the conductive metal inside.

However, it's wise to always use consistent colors for similar types of wiring within the layout. For example, you may choose to use brown wire for DC wiring and red wires for DCC bus wiring. For more information on DC and DCC, see our guide to DC vs DCC model trains.

It's also advisable to always label the start and end of all the cable runs that you have on your model railroad. This will greatly aid in diagnosing any electrical problems that may be encountered in the future and will help to avoid wasting time trying to identify wire runs on the layout.

Model Train Wire Size Summary

Wiring model train layouts using the correct O gauge wiring gauges and 00 gauges wire types is an important part of designing and building model train electrics.

It's important to choose the correct model rail wire size when creating a layout or connecting wire for model railways as part of the build process.

0.64mm (23 gauge) wire is ideal for track feeders and dropper wires due to the small length of these wire runs.

The recommended wire sizes for the bus wiring can be summarized as follows:

  • Small layouts (8'' x 4'' and below) use 1.29mm diameter – 18 gauge.
  • Medium-sized layouts (up to 12'' x 16'') use 1.62mm diameter – 16 gauge.
  • Large layouts (12'' x 16'' and above) use 2.5mm diameter – 14 gauge.

There are two main choices for model railroad wire construction. Solid core wire is better for straight wire runs and stranded wire is best for any wires that need to bend, twist or will frequently move.

It doesn't matter which color wire you use for wiring a model train layout. However, it's advisable to use different colors for specific groups depending on the function of that particular wire. For example, you may use brown wire for DC connections and red wire for DDC bus wiring. Being consistent with this will help to quickly diagnose any wiring or connection issues that you may have further down the line.

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