SELECTING A FIBER OPTIC PATCH CORD
I receive many questions when it comes to the topic of Networks and Datacom, but one subject I believe many can benefit from is how to determine the differences between one fiber optic patch cord and another. Now, fiber optic patch cords come in a variety of cable and connector types. In order to obtain the proper patch cord you need to determine several attributes:
Cable Type — Fiber Optic cable comes in two general types, Single-Mode and Multi-Mode fiber.
Single-Mode fiber cable generally has a 9 Micron diameter glass fiber. There are two sub groups (referred to as OS1 and OS2) but most cable is "dual rated" to cover both classifications.
Multi-Mode fiber cable can have several different diameters and classifications of fiber strands.
The two diameters currently in use are 62.5 Micron and 50 Micron.
Within the 50 Micron diameter Multi-Mode cable, there are three different grades (referred to as OM2, OM3, and OM4). The cable types used in the patch cord should match that of the network cabling to which they are attached via the patch panel.
The fiber cable may be available in different "jacket diameters" (such as 2mm or 3mm). Thinner diameters (1.6 or 2mm) may be preferable in dense installation within a single rack since they take up less space and are more flexible.
Cables that route from rack to rack (especially via cable tray) may be more suitable if they have the thicker jacket that results in larger diameters thus making them more rigid.
Flammability of the jacket material could become an issue if the area they are in has special requirements for flame spread or products of combustion in case of a fire. In these cases, patch cords may have to be classified as "Plenum Rated" (OFNP) rather than "Riser Rated" (OFNR).
Simplex or Duplex — Unlike copper patch cords which send information in both directions (having multiple pairs of conductors with which to do so), most fiber patch cord cables have a single strand of fiber allowing for signal flow in one direction only.
Connecting equipment so that it can send and receive information requires two strands of fiber (one to transmit and one to receive information). This can be accommodated by using two "Simplex" (single strand of fiber) cables for each equipment interconnection or a "Duplex" cable, with conductors and/or connectors bonded together in pairs.
Length — Overall length of the patch cord may be specified in feet or meters, depending on your preference.
Connector Type — See the connector type descriptions below. Some patch cords may have different connector types on each end to accommodate interconnection of devices with dissimilar connectors. In some cases, there may be a connector on only one end, and bare or unterminated fiber on the other. These are usually referred to as "Pigtails" rather than "Patch Cords".
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