Friday, March 25, 2011

Cable Markings

Have you examined the outside jacket of a twisted-pair or fiber-optic cable? If so, you noticed many markings on the cable that may have made sense. UL has requirements on how their designations are applied and the FCC requires that the category be placed every foot. For cables manufactured for use in the United States and Canada, these markings may identify the following:

  • Cable manufacturer and manufacturer part number.
  • Category of cable (e.g., UTP).
  • NEC/UL flame tests and ratings.
  • CSA (Canadian Standards Association) flame tests.
  • Footage indicators. Sometimes these are "length-remaining markers" that count down from the package length to zero so you can see how many feet of cable remains on a spool or in a box. Superior Essex ( is one cable manufacturer that imprints length-remaining footage indicators.

Here is an example of one cable's markings:
000750 FT 4/24 (UL) c(UL) CMP/MPP VERIFIED (UL) CAT 5e
These markings identify the following information about the cable:
  • The 000750 FT is the footage indicator.
  • The 4/24 identifies the cable as having four pairs of 24 AWG wire.
  • The (UL) symbol indicates that the cable is UL listed. Listing is a legal requirement of the NEC.
  • The symbol c(UL) indicates that the cable is UL listed to Canadian requirements in addition to U.S. requirements. Listing is a legal requirement of the CSA.
  • The CMP/MPP code stands for communications plenum (CMP) and multipurpose plenum (MPP) and indicates that the cable can be used in plenum spaces. This is the NEC flame/smoke rating.
  • The term VERIFIED (UL) CAT 5e means that the cable has been verified by the UL as being Category 5e compliant (and TIA/EIA-568-B compliant). Verification to transmission properties is optional.
  • SUPERIOR ESSEX is the manufacturer of the cable.
  • COBRA is the cable brand (in this case, a Category 5e–plus cable, which means it exceeds the requirements for Category 5e).
  • The numbers 2319 indicate the date of manufacture in Julian format. In this case, it is the 231st day of 2009.
  • H indicates the Superior Essex manufacturing plant.
Some manufacturers may also include their "E-file" number instead of the company name. This number can be used when calling the listing agency (such as the UL) to trace the manufacturer of a cable. In the case of UL, you can look up the E-file numbers online at
Cables marked with CMR (communications riser) and CMG (communications general) must not be used in the plenum spaces.

Common Abbreviations

So that you can better decipher the markings on cables, here is a list of common acronyms and what they mean:
  • NFPA The National Fire Protection Association
  • NEC The National Electrical Code that is published by the NFPA once every three years
  • UL The Underwriters Laboratories
  • CSA The Canadian Standards Association
  • PC The Premise Communication Cord standards for physical wire tests defined by the CSA
Often, you will see cables marked with NFPA 262, FT-4, or FT-6. The NFPA 262 (formerly UL-910) is the test used for plenum cables. The FT-4 is the CSA equivalent of UL 1666 or the riser test, and FT-6 is the CSA equivalent of NFPA 262.


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