Wire and Cable Coding Explained

Wire and cable fall into two primary categories: Electrical power and communication.

Electrical power cable

Types of electrical cabling can range from conventional house wiring, high voltage and current wiring for industry, to power transmission lines. Each of the types has a multitude of specialized coverings and sizes based on applications and use. Electrical underground power transmission cables and undersea optical communication cables are at one end of the spectrum for size and protection. Aviation and aerospace are at the other end of durability and specialization.

Communications cable

Data along optical cables transmits electrical signals or data using light rays. Data and communications cables have their standards but also can fall under the same electrical code's references for labeling installations. Communications or data transmission cables designed to transmit data signals are much different than electrical wiring. These cables range from twisted pairs and coaxial for networking, USB for computers, and bundled fiber optic cables for transmitting large volumes of information across greater distances.

Common types of cable

Some of the more common types of cable are named according to end-user requirements. These include:

  • armored cable;

  • sheathed cables;

  • metallic sheathed;

  • coaxial;

  • insulated;

  • NM (non-metallic) cable;

  • UF (underground feeder) cables;

  • underground or undersea cable;

  • electrical vehicle cable (EV);

  • high voltage;

  • submersible;

  • solar; and

  • mining cable

How Are Different Types of Cable Manufactured?

  • Optical wire is manufactured by drawing glass into fibers. The glass or optical cable must remain in a semi-molten state at very high temperatures to be drawn and annealed by external heating into thinner individual glass tubes. Metal or copper wire is forced through dies of smaller dimensions and annealed by passing electricity through the metal to create a thinner wire.

Covering

  • The process of covering and labeling/coding bare wire and glass filaments is generally quite similar.Some factories draw the metals, primarily copper, and cover it during the drawing process. Most of the methods for covering wire or creating the cables originate with the bare drawn wire and extrude the specialized coverings onto the individual wires, stranded, or bundled cables.

Stranding & Sheathing

  • Metallic wire and ribbon fibers require secondary operations for stranding and sheathing. These operations wind or strand multiple wires or optical ribbons into bigger bundles with sheathing and jacketing needed for the final use of the cable.

Labeling/Coding

  • Both types of wire and cable, once covered, must be identifiable by color or coding applied to their surface. The standards for these codes are set by multiple organizations internationally and nationally, depending on their end uses.

What are the Standards & Codes Used to Identify Wire and Cable?

  • There are seemingly as many different standards guiding wire and cable labeling and installation as there are types of wire and cables. These standards or regulatory codes pertain to labeling the outer jacket during manufacture and installation. Some common standards include:

    • UL Certification;

    • Mil-Spec requirements;

    • NFPA and NEC;

    • EIA;

    • TIA;

    • IEEE;

    • NEMA; and

    • SAE standards

Let’s take a look at the NEMA standard for PTFE (polytetrafluoroethylene) insulated wire.

Example: NEMA HP3 PTFE

The image to the right depicts an example NEMA HP3 PTFE code broken into its individual components. All PTFE insulated wire codes begin with ‘HP3.’ After a hyphen, a series of letters and numbers represent properties of the wire such as its gauge, the material it’s made from, and the color. Before investigating what each of these characters represents, it’s important to note that all PTFE insulated wire begins with ‘HP3.’ The rest of the code differs based on the wire’s properties.

1. NEMA Type

The first letters after the hyphen represent its NEMA type. Possible NEMA type values include E, EE, and ET. In this example the NEMA type is EE, which is intended for high-temperature applications and can withstand up to 1,000 volts RMS. Wire with this NEMA type is well-suited for use in high-frequency circuitry.

2. Construction

The second element after the hyphen represents one of two types of construction: wrapped (W) or extruded (X). In the example above, the letter W indicates that this wire is wrapped.

3. Conductor Material

The next letter is the conductor material, represented by a single letter in the range B to G. Possible conductor materials include copper, copper alloy, and copper-clad steel. These conductor materials may be either nickel- or silver-plated. The example above uses silver-plated high-strength copper alloy (SCA), represented by the letter D.

4. AWG Nominal Diameter

After conductor material, the wire’s AWG nominal diameter from 32 gauge to 4/0 is indicated by a single letter in the range A to Z. The closer to the end of the alphabet the letter is, the larger the diameter of the wire.The example above shows a value of D, indicating a 32-gauge wire.

5. Number of Strands

The next character represents the total number of wire strands included in the cable. The number of strands ranges between 1 and 2,109, depicted by letters in the range A to W. The example above has 7 wire strands, represented by the letter B.

6. Color

The last character is a single digit between 0 (black) and 9 (white) representing the color of the wire’s outer jacket.

How Are the Codes Printed on the Outside Cable Coating?

There are numerous challenges for printing high-quality, long-lasting codes on the outer jackets of cables. Some jacket material is different in color to indicate amperage/gauge or gray for underground cable. Any printing must have a contrasting color to be visible. Materials covering wire vary greatly depending on the applications or end-use, providing even more variables for the inks and printing equipment. Some coatings could be metal-clad or metallic mesh. Other materials, like Teflon, are non-porous. Manufacturers should take the printing ink and application into consideration. The coding must endure the same types of conditions as the jacket. For more information, read our post about other factors affecting print quality that you must be mindful of, such as the type of jacket material, process line speed, and more.

What Equipment Is Used for Printing the Codes?

Manufacturers understand that the speed & quality of applying the label must not slow down the process line. Likewise, changing over the inks, maintenance, and programming must have minimal effect on production. Today, most high-volume cable manufacturers use continuous inkjet (CIJ) equipment to apply their codes to the cable’s outer jacketing. This type of printer can meet the demands of high-speed manufacturing. CIJ printers expel electrically charged ink droplets through a print head that doesn't require direct contact with the wire coverings. Without direct contact, the printers can print on varying contours, sizes, and materials. Computerized controls of these devices allow quick programming, different printing fonts, symbols, logos, and variable coding at high speeds. Newer CIJ printers have increased the interval between required printhead cleaning and simplified the cleaning process to improve uptime. industrial printing equipment must also be able to operate in demanding, ever-changing environments in factories. If the printer fails, the extruding process won't stop the run until the coating material runs out. Lack of labeling or poor quality causes waste and reworks that increase costs. Manufacturers understand that capital investment in printers only makes sense if process efficiencies improve to maximize uptime and minimize costs. CIJ printers fit those requirements. One of our most popular models, the DuraCode CIJ printer, excels at non-contact printing on curved surfaces covered with nearly any type of substrate.

Does the Ink Being Used Change with the Cable Jacket Materials?

The type of ink used in wire and cable coding has an impact on the printer operation and quality of the printing. Inks should be tested individually for the equipment and types of cable jacket materials specified. There are several important factors to consider to avoid downtime, maintenance, and quality issues, including:

  • Whether the ink is formulated specifically for the intended use case;
  • Whether the ink is compatible with the printing equipment or surface; and
  • The purity of the input materials used in formulating the ink.

Cutting Corners Costs Money in the Long Run

Home and office inkjet printers have similar requirements. The printer must adjust for the type of paper, such as standard bond vs. glossy. Off-brand ink can save costs initially, but it may clog the print heads or produce low-quality letters or photos. Industrial printing is much more demanding, and the long-term costs associated with cutting corners are much higher.

Specially Formulated Industrial Inks

Look for guaranteed compatible industrial ink. Specially formulated inks are necessary for high-temperature applications, no-transfer, and abrasion-resistance, and printing intense colors on colored cable jacketing or coatings requires specially formulated inks. Specialized inks are even available to comply with DOD military specifications for moisture, chemicals, solvents, and abrasion resistance. Whatever your specific requirements may be, inks can be custom formulated for new or unique applications.

Contact InkJet, Inc. for More Information About Cable-Marking Printers

Whether you need help finding the right printer for coding and marking wire/cable, or the perfect ink for your industrial print job, the experts at InkJet, Inc. can help. Fill out our online contact form or call (936) 856-6600 to get started!

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