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UL Cable Harness Design: Low-Risk Wire Options

Steven J Goodman
Written by Steven J Goodman
Posted on February 26, 2020 at 10:44 AM

One of the first steps in designing a custom cable assembly is selecting the wire. There are lots of options to choose before the design can be frozen. Selecting a UL spec wire can be challenging if you are unfamiliar with the standards but knowing just a few options allows for a simplified design.

This means a faster quote; a defined wire standard allows manufacturers to provide firm pricing and lead times for an evolving design. With a faster quote, and wire that is readily available, custom designs can be brought to market quicker with less sourcing and design risk.

Learn 10 Ways to Select the Correct Connector for Your Custom Cable Assembly!

Benefits Using UL Wire in Your Cable Assembly

UL wire is extremely common, and in many cable assembly designs, it is the preferred wire choice. Most of the name brand North American wire manufacturers have their own wire specifications that point to UL wire specifications. For example, there are several manufacturers that make UL1007 wire, and they each have their own assigned P/N scheme, but it all is derived from the primary UL specification.

Another benefit to using UL cable is that the wire specifications are printed along the perimeter of the wire jacket. If you have spent time working with cables, you may have noticed the text printed along the outside jacket.

Examples of wire jackets clearly indicating the UL markings

Examples of wire jackets clearly indicating the UL markings.


Typically, this is a small-font, finely printed label that runs the entire length of the cable. Hopefully your cable section is long enough to ascertain the entire sequence. Otherwise, you may be left with only a portion of the information. If you look carefully, you should see a series of letters and numbers. You should see a UL specification that is sometimes defined as Appliance Wiring Material (AWM) and other times defined as Machine Tool Wire (MTW).

Many UL specs are dual use, and by slightly increasing the jacket thickness, one can realize a dual rating such as UL1007/1569 or UL1015/1230. This text printed along the jacket may also define the flammability rating such as VW-1 or FT-1. Another valuable piece of information that is typically printed along the wire jacket is the maximum rated voltage and temperature. Some jackets carry a different maximum rated voltage that varies with temperature, so it’s not uncommon to see two different temperatures and voltage printed along the wire. It’s always best to refer to the wire manufacturer to clarify the performance specifications.

If you are stuck searching for a wire option, here are a few common wire standards to start the process.

UL1007/1569

One of the most common wire standards is UL1007/1569. This specification covers single conductor “hook up” wire in sizes from 30AWG to 8AWG with two different temperature ratings: 80°C and 105°C. All the standard wire colors are typically available with this specification. The PVC jacket thickness drives the temperature rating with a thicker jacket, allowing for high-temperature exposure of up to 105°C. UL1007/1569 also features a UL VW-1 flame test rating while offering a voltage rating of 300VDC.

UL1015

A single conductor with PVC jacket is another simple “hook up” wire, but this is ideal for higher wire AWG and high-voltage applications. UL1015 is offered up to 10AWG, which is one of the larger sizes of these common “hook up” wires. At less than 0.2” in diameter, the cable is still stout and minimum bend radii should be considered. This is rated for high-temperature applications of 105°C and can support voltages in excess of 600VDC. UL1015 offers a horizontal flame test rating.

UL2725

Four conductors bundled together in one jacket ranging from 26-30AWG. Usually, this includes one twisted pair to improve signal quality. The internal jacket colors are commonly red, black, green, and white, with a black outer jacket. These are rated for very low-voltage applications up to 30VDC. Their temperature is typically rated for applications up to 80°C. UL2725 spec offers a shielded overall cable and vertical flame rating of VW-1. Ideal for USB cable type applications, this UL spec is appropriate for a low-voltage supply and twisted pair for signal.

Summary

If you’ve visited an electronics distributor’s website and searched wire, the options can be overwhelming. This is especially true if you are searching for a multiconductor wire with a specialty rating. The different options seem endless: wire jacket material, shielding, drain wire, jacket color, wire lay pattern, etc. But if your application is relatively benign, and the environmental requirements aren’t severe, consider using UL1007/1569, UL1015, or UL2725 wire options to get your project moving. Afterall, most projects just need a functional prototype to verify the electrical schematic and design. Accomplish this by using standard, readily available wire that can be quoted and built quickly.


Topics: Cable Assemblies


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