Hook-up Wire
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Layout Wiring
No matter what kind of layout you have, large or small, DCC or conventional you will have to do some wiring. We carry a number of items that you will find invaluable to your wiring efforts. We are also open to suggestion so if you feel we should add some more items please send us e-mail or give us a call and we will investigate.
Wire is one item that every model railroader will need meters and meters of! Even if you are using DCC you will have lots of items that must be wired on your layout. RailTronics has a complete selection of hook-up wire available for the model railroader. There are a few key topics you should review prior to selecting your wire. These topics, which are reviewed below, include:
- The architecture of your overall wiring system
- Wire size
- Wire Type - solid vs. stranded
- Wire colours
Wiring Architecture
As a result of the way current and resistance are related (Ohm's law) you want to construct your wiring in such a way that it can handle the current demand (Load) of your layout while minimizing the losses due to resistance, all this balanced against the cost! As you push more current through a greater distance of wire the voltage drop increases. Voltage drop means your locomotives appear to slow down, or your lights are not as bright. This voltage drop is directly related to the resistance and the current (E = IR). There are two strategies to solve this problem
Run more wires to split the current load.
Run bigger wires to reduce the resistance per unit distance.
These two options are the reason your wiring system should
have a hierarchical architecture. At a minimum your wiring system should
consist of two levels and for a very large layout possible three
levels. This architecture is similar to way your home is wired.
The diagram below shows the typical two-layer architecture for layout wiring. In this architecture the layout is broken down into:
The bus system that supplies power to the various feeders in your layout and
The feeders
that supply the various devices on your layout that require power.
Wire Sizes
Wire comes in different diameters that are sized in AWG units (American Wire
Gauge). The smaller the AWG number (i.e. 8 vs. 14) the larger the
diameter of the wire. A wire with a larger diameter has a larger
surface area and thus a lower the resistance per unit distance meaning losses
are reduced. A wire with a larger diameter thus has a higher
current (load) capacity.
Returning to our architecture:
Your power bus should be a larger size (diameter) of wire depending on the layout size and current consumption. The wire size is recommended to be somewhere between 12 AWG and 18 AWG again depending on size. A large HO/O scale layout should work at the upper end (12/14 AWG), while a larger N scale layout could work in the middle of range (14-16 AWG) and a small layout at the bottom end of the range (18 AWG).
For the power feeders smaller sizes are recommended. Again depending on the current load and the length of the feeder the use of 18 AWG to 24 AWG is recommended. For heavy current consumption (i.e. a large G/O scale locomotive) or for very long feeders you are better at the larger end of the range (18 AWG) while for smaller N scale locos or short feeders the lower end of the range should be sufficient.
Wire Type
Wire is available in stranded and solid forms. Both forms of wire have inherent advantages and disadvantages that mean a model railroader has to choose the appropriate wire for the application.
- The advantage and disadvantage of solid wire is its rigidity. The rigidity means the wire is does a neat job, can be bent and will stay in place. The rigidity also means the wire will tend to break if bent often or if the wire is damaged in the process of removing (stripping) the insulation. Solid wire is an excellent choice for power busses of your layout. Once built the bus system should be solid/rigid, look neat and tidy, rarely undergoes significant change and is isolated from the actual layout elements so there should be no movement. As a caution solid wire in 24 and 26 gauge is readily available in the surplus market from old telephone systems. From bitter personal experience we recommend against using this wire in the feeder side of your layout!
- Stranded wire is constructed from a number of strands of much smaller solid wire. This construction is described by two numbers that look like a fraction where the first number represents the number of strands and the second number the AWG of the strands. For example 7/30 is constructed of 7 strands of 30 AWG solid wire. As a result of this construction the wire is flexible and can thus be used to snake around the bottom of your layout and up through small holes in the layout. Stranded wire is generally easier to solder (many times it comes pre tinned) and is less likely to break (even if damaged during stripping). Stranded wire is our recommendation for the feeders in your wiring architecture.
Wire Colours
Wire is available in a rainbow of colours. The key element in your selection of colours is to be consistent. There are also some wire colour standards that have been defined by the NMRA and MOROP (more info at their web-sites). Listed below are some typical colour schemes you could employ, however as stated earlier define your own standards, document them and then stick to them. If you religiously adhere to your standards you will be much happier if and when you have to troubleshoot your wiring system.
Wire Colours & Typical Uses |
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|
Colour |
Typical Use |
Colour |
Typical Use |
Black
|
Ground
wire DC |
Green
|
Switch
Machine Normal Route |
|
Brown |
Märklin Ground Wire Alternate
Ground DC |
Blue |
Switch
Machine Diverge Route |
|
Red |
Power
wire DC / Märklin |
Violet |
|
Orange
|
|
Grey
|
|
|
Yellow |
Power
Wire for Lighting |
White |
|
Wire Specifications
The chart above lists the size and specifications of wire currently available from RailTronics. Our wire is only available in stranded form and aimed at the feeder (consumer) side of the equation. For your power busses we recommend you use a solid wire and the best available solid wire is used in house wiring. You usually can't beat the price at your local hardware so we don't carry it.
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Hook-up Wire Specifications |
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|
Wire Size (AWG) |
Type & Composition |
Area (mm2) |
Current Capacity (A) |
Resistance (Ω mft) |
|
24 |
Stranded 7/32 |
0.227 |
4.9 |
25.7 |
|
Stranded 7/30 |
0.355 |
6.3 |
16.6 |
|
|
Stranded 10/30 |
0.507 |
8.4 |
11.4 |
|
|
Stranded 16/30 |
0.810 |
8.5 |
7.15 |
|
|
A = Ampere
= Current capacity of this wire Ω
mft or Ohm/mft = Resistance per 1000 feet in Ohms All wire
is CSA/UL approved for 90oC and 300 Volts All wire
is stranded and tinned 7/32 means 7 strands of 32 gauge wire |
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last updated this page on September 13,
2006.