Wire marking can be interpreted several ways. For example, UL has a variety of labels used to identify wires and cables certified for specific purposes. For other applications, insulation color coding schemes are used to identify wires. However, the wire marking we'll be talking about are the labels used to number or mark both ends of wires such that they can be identified.
The purpose of this type of wire marking is to help ensure the wires are correctly terminated when installed, and to simplify maintenance, repairs and upgrades in the future.
Not all wires are labeled. For example, wires in electronic devices and vehicles are not marked with labels, although they may use color-coded insulation that allows the wire to be identified and traced. Wires in residential homes are typically not labeled, but wires in most other types of buildings are. Wire marking is most commonly used in commercial buildings and industrial applications, as well as on wires used to connect components in a large system, such as the wiring in aircraft.
Wire Marking Standards
There are no overall standards that require wire marking. However, some industries have codes or standards that require specific types of wire marking.
In some cases, such as for some aircraft wiring, laser marking of the wire is required. International standards for laser wire marking equipment include:
- SAE AS5649 - Wire and Cable Marking Process, UV Laser.
- ASD EN4650 - Wire and Cable Marking Process, UV Laser.
- SAE ARP5607 Rev A - Legibility of Print on Aerospace Wires and Cables.
- ASD EN3475 Part 706: Aerospace series Cables, electrical, aircraft use - laser markability.
- ASD EN3838.
- FAR 25 - Permanent, Non-Aggressive Wire Identification.
However, in most cases either shrink tube labels, or self-laminating wire wraps are the appropriate wire marking methods.
Telecommunications Wire Marking
An application for which there is a labeling standard is telecommunications wiring used in commercial buildings. The standard that applies is ANSI/TIA/EIA-606-A (Administration Standard for the Telecommunications Infrastructure of Commercial Buildings). This standard specifies that wire markings must be suitable for the environment in which they are used, be made using a mechanical printer, and the standard provides a specific color coding scheme to be used.
Selecting the Right Wire Marking Material
Wire markers can be made from different materials and printed in various ways. Even when there is no published standard, the wire marking materials must be suitable for the environment. The environmental factors that must be taken into consideration include temperature, moisture, exposure to chemicals and salt water spray, and exposure to sunlight. Using wire markers that are resistant to all of these, such as DuraLabel shrink tube wire markers, ensures your wire markers will last under any circumstances.
Wire Marking with Shrink Tubes
Shrink tube wire marking has a number of advantages:
- They provide long-term, permanent wire marking, that, when DuraLabel shrink tube sleeves are used, is resistant to most environments. (When greater chemical resistance is needed, DuraLabel offers a special ribbon for printing shrink tube labels with high chemical resistance characteristics.)
- Shrink tubes are easy to print and install, just slip them over the end of the wire and use a heat gun to shrink them to a tight fit.
- DuraLabel shrink tubes are available in eight colors, providing an easy way of color coding wires.
The disadvantage of shrink tubes is that they cannot be installed on wires that are already terminated, and they will not fit on larger size cables.
Wire Marking with Self-Laminating Wire Wraps
The alternative to shrink tubes are self-laminating wire wraps. These are adhesive labels with a long clear tail. An opaque section is printed with the wire identification information, then when applied to a wire, the clear tail wraps around the wire covering and protecting the printed label. Wire wraps can be applied after the wire is terminated, and they are available in larger sizes so they can be used on cables as well as wires. Self-laminating wire wraps are available in a wide range of colors, providing flexibility for color coding wires and cables. The disadvantage of self-laminating wire wraps is that they do not work well on small wires.