A Guide to Cable Types and their Identification

In this article we are going to take a brief look at the three main types of cable; fiber optic, coaxial and twisted pair. Additionally, information on the classes and rating of each of these types of cable will be covered.

Where appropriate, we will also discuss the various markings that can be found on these cables, and various other identifying marks.

Fiber Optic Cable

The main distinguishing factor between different types of fiber optic cables is the physical color of the sheathing that covers the actual cable strands. Cables of the same color, will always be of the same type. The most common of these are:

  • Aqua Blue – This is a multimode (50/125) (850 nm Laser-optimized) (TIA-492AAAC) (OM3, OM4) cable. It’s more common, short form code is 850 LO 50 /125.
  • Orange – This could be a Multimode (50/125) (TIA-492AAAB) (OM2) cable. It’s more common, short form code is 50/125.
  • Orange – This is a multimode (62.5/125) (TIA-492AAAA) (OM1)) cable. It’s more common, short form code is 62.5/125.
  • Orange – This is a multimode (100/140). It’s more common, short form code is 100/140.
  • Yellow – This is a Single-mode (TIA-492C000 / TIA-492E000) (OS1, OS2) cable. It’s more common, short form code is SM/NZDS, SM.

NOTE: There are three orange fiber optic cables in the list above, this is not an error. There are three types of orange cable. In order to identify just which of the three types you are looking at, you will need to check the actual markings on the cable.

Additionally, when fiber optic cables are used in a military environment (including by sub-contractors), a different color scheme is typically used.

Furthermore, the appearance of fiber optic cable is affected by the actual sleeve the cable is housed in. Some are armored, with a much thicker outer jacket and internal metal sleeve surrounding the individual strands of fiber. There’s also a kevlar weave that helps protect the fiber stands while also increasing the tensile strength of the cable. These armored fiber cables are much thicker than non-armored cables.

There will also be markings on the fiber optic cable that tell what material the jacket is made from. Some of these markings include:

  • PVC – Polyvinyl Chloride
  • PE – Polyethylene
  • PUR – Polyurethane
  • PBT – Polybutylene terephthalate
  • PA – Polyamide

Fiber optic cable can also be rated for its fire resistant properties, and the common markings that demote this are:

  • CM – Communications Rated. This means that cable is suitable for use in any application where the building’s fire code does not require fire resistant cabling to be used.
  • CMR – Communications Riser. This is a type of twisted pair cable that has been specially designed not to propagate fires between floors, or along cabling ducts.
  • CMP – Communications Plenum. This cable is suitable for use in plenum spaces, where no other fire retardant ducts are being used. It is self-contained within a fire resistant jacket.

Twisted Pair Cables

Depending upon who you are speaking to, twisted pair cables will either be called RJ45, 8P8C or just by their category rating, e.g. Cat5 cable. In effect, all of these cables are of the twisted pair family and are the primarily type of cabling used in most communications infrastructure.

At first glance, it can be very difficult to visually distinguish different categories and types of twisted pair cables. Just like fiber optic cables, some twisted pair cables are shielded and are thus thicker than their non-shielded counterparts. For definitive identification, the actual markings on the cable will instead need to be used as a guide.

When it comes to twisted pair cable markings, there can be a lot. Some of the markings that can be found include:

  • SHIELDED – This denotes that the cable jacket contains a shield to limit RF emissions.
  • UL – The cable is listed as a conforming to UL fire standards.
  • ETL – The cable is listed as a conforming to ETL fire standards.
  • Distance Rating – An indication of how long the cable can be, before signal degradation becomes an issue. For example, most are marked as 1000FT, meaning 1,000 feet is the potential maximum length of the cable.
  • Distance Marking – An indication of how much cable is on the reel or in the box. Most reels and boxes of cable come in 1,000 foot spools but can be special ordered to come in more or less. The markings are usually separated by a few feet and the actual length of the cable can sometimes be difficult to determine so you should always check at least two consecutive markings, in order to determine if the numbers are ascending or descending.
  • Category – Most common are Cat5, Cat5e and the newer Cat6. There are others out there but nowadays they are rarely used.
  • CM – Communications Rated. This means that cable is suitable for use in any application where the building’s fire code does not require fire resistant cabling to be used.
  • CMR – Communications Riser. This is a type of twisted pair cable that has been specially designed not to propagate fires between floors, or along cabling ducts.
  • CMP – Communications Plenum. This cable is suitable for use in plenum spaces, where no other fire retardant ducts is being used. It is self-contained within a fire resistant jacket.

This is a basic list of the markings that can be found on twisted pair cable. Depending upon the manufacturer, or even where the cable was manufactured, there can be others.

Coaxial Cable

Usually shortened to just coax, this cable was invented by Oliver Heaviside in 1880, just one year before Alexander Graham Bell invented the twisted pair cable. There are three main types of coax cable currently in use, and the best way to identify these is actually from the physical diameter of the cable. The three main coax cables include:

  • RG-59 – This is the thinnest member of the coax cable family, originally used for carrying video signals. The outer diameter is 6.15mm, and the diametric is 3.7mm.
  • RG-6 – Most often used for satellite communications cables. The outer diameter is 6.9mm, and the diametric is 4.6mm.
  • RG-11 – This is the cable that is used to build BNC style LAN networks. It has an outer diameter of 103mm

Coax cable can also be shielded in different ways, effecting the overall shielding properties. There are three main types of coax cable shielding, and these are quite easy to visually identify.

Single Shielded – The shielding layer is made up of a weave of braid (much like cloth).

Duel Shielded – A layer of metallic foil is wrapped around the internal braided shielding layer.

Quad Shielded – The same as duel shielded, but with two layers of each type of shielding.

There are also some standard markings used to identify certain properties of coax cable, and this includes the material the sleeve is made from, and how it has been manufactured. These markings include:

  • PE – Solid Polyethylene.
  • FE – Foam Polyethylene.
  • FS – Foam Polystyrene.
  • ASP – Air Space Polyethylene.
  • ST – Solid Teflon.
  • AST – Air Space Teflon.

4 Responses to “A Guide to Cable Types and their Identification”

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