Identifying Installed Fiber Optic Cables

Cable ID

Identifying Installed Cable

You’re on site and need to match an installed fiber optic cable. Unfortunately, the actual spec is long gone, and you’re not sure what you’re looking at. Labeling conventions, plus the TIA/EIA Standards, can help you narrow the field if you can’t locate a part number.

We’re also available to help with cable identification – contact us at any point. Looking for fiber? Find our bulk cables here.

Key Steps for Cable Identification

  1. Check the jacket color. In non-military applications:
    • OM1/OM2 = orange
    • OM3 = aqua
    • OM4 = violet or aqua
    • OS2 = yellow
  2. Read the print legend
    • Look for OM1 (62.5/125), OM2 (50/125), OM3 (50/125), OM4 (50/125) or OS2 (9/125)
    • Look for a rating, such as OFNP or OFNR
    • Look for any notes about the construction (duplex, tactical, etc.)

Check the Jacket Color

First, always look at the color of your cable. Per TIA/EIA standards, the following color coding applies for non-military fiber optic installations:

  • Multimode OM1 = Orange or Slate (Watch for this! OM1 is not compatible with connectors for OM2/OM3/OM4)
  • Multimode OM2 = Orange
  • Multimode OM3 = Aqua
  • Multimode OM4 = Aqua or Erika Violet (Magenta)
  • Single Mode OS1/OS2 = Yellow

However: Per TIA 598-C, it is permissible to use different jacket colors as long as the cable is identified in the print legend. Please check the print legend or contact the manufacturer before trying to make a positive ID!

Print Legends

Print Legend

Even if you have already looked at the cable color, check the print legend. It may immediately solve your mystery. However, since print legends can get detailed, read on for a breakdown of key abbreviations in an example SSF™ cable. While print legends vary by manufacturer, notation for cable type and rating tends to be fairly consistent.



MMF (50/125) : Multimode Fiber, 50/125

In this case, 50/125 corresponds to the core (50 µm) and cladding (125 µm) measurements of the actual optical fiber. These measurements are not the actual outer diameter of the cable; they correspond directly to the optical fiber itself.

This notation indicates that you are looking at either OM2, OM3, or OM4, as they all have this core and cladding measurement.

Other abbreviations you might see:

  • SM (9/125): Single mode fiber with a 9 µm core and 125 µm cladding. This is either OS1 or OS2 graded glass.
  • MMF (62.5/125): Multimode fiber with a 62.5 µm core and 125 µm cladding. This is OM1 graded glass, which is not compatible with 50/125 multimode.


In our case, this is a code indicating the type of optical fiber. The OM3 notation indicates that this cable is multimode grade OM3.

On other cables, you might see codes like this incorporating -OM2, -OM4, or -OS2, which also correspond to the grade of optical glass.

DUPLEX: Cable Construction

SSF™ cables often note the type of cable construction on the print legend. You might also see cables marked “Micro Distribution,” “Direct Burial, or “Tactical,” etc.

OFNR FT4: Jacket rating, indicating where the cable may be safely installed.

You might also see:

  • OFNR FT4: Optical Fiber Nonconductive Riser (FT4 is the Canadian equivalent)
  • OFNP FT6: Optical Fiber Nonconductive Plenum (FT6 is the Canadian equivalent)
  • OFCR: Optical Fiber Conductive Riser
  • OFCP: Optical Fiber Conductive Plenum
  • LSZH: Low Smoke Zero Halogen
  • OSP: Outside Plant

Conductivity (Nonconductive vs Conductive): Fiber optic cables, being glass, are nonconductive when by themselves. Any cable noted to be conductive includes a metal or other conductive component in the jacketing. This would apply to armored cables.

Riser cables have less stringent fire rating requirements, as they are intended for riser spaces, such as elevator shafts and vertical conduits between buildings. While plenum cable can be used in place of riser, under no circumstances should riser be substituted for plenum.

Plenum cables are constructed to be the safest of the listed cable options in case of fire. As a result, they can be run in plenum spaces, which include open spaces above the ceiling or below the floors of a building (and sometimes ductwork) used for air circulation.

In Europe, LSZH (Low Smoke Zero Halogen) cables are similarly designed to be less toxic in case of fire.

OSP: The cable is suitable for outside plant applications, such as direct burial. These cables are often unsuitable for indoor installation due to fire code regulations.

While this print legend does not state the part number, from the data above there is a reasonable chance of tracking down a matching or similar cable.

Further Reading:

Identifying Installed Fiber Optic Cables