How to use a Fiber Patch Cord

Fiber optic patch cables are a very important part of any network. They are used to connect different network devices of various types with each other. These cables are produced in many different colors so they are easily distinguished and combined. Generally they are used for short range connections and usually they are no longer than 2 meters in length. Every patch cord is fitted with a specific connector at each end. When installing patch cords there are some key steps and things to note:

 

Be careful with the bending. The bending of a cable is measured as bending radius. There are 2 relevant minimum bending radii, one is for patch cord installation and one is for the patch cord once it’s installed. During the installation of the patch cord the minimum permited bend radius is greater than it is when the cable is placed in its final position. This is mainly because during the installation there is a lot of pulling and tension over the cable.

Make sure not to go beyond the maximum pulling forces during its installation. This will ensure the cable is not damaged and its performance impaired during installation.

Minimize the twisting and bending of the patch cord during its installation.

During patch cord installation, cable management precautions that should be observed include the elimination of cable stress caused by excessive tension, tightly bunched cords and sharp bends.

Always make sure not to exceed the temperature variations because more than often attenuation increases with temperature, typically 0.4% per oC for Cat 5e cables. The temperature variations can be found in the table below.

 

It is highly advisable to keep the cables in place using zip ties or other kind of patch management systems. For easier cable management and identification always keep the groups of cables as small as possible.

 

Always label the cables for easier identification. In a professional network infrastructure the cable labeling is covered by the latest labeling standard, ANSI/TIA/EIA 606A. This standard recommends that a printed self-laminated wrap around label should be used whenever possible.

 

Keep in mind that Alien crosstalk (AXT) may occur and it should be minimized if possible. The Alien crosstalk is an electromagnetic noise that can occur in a cable that runs alongside one or more other signal-carrying cables. This is most commonly found with 10G cables. This crosstalk is especially important because it can cause a lot of problems and it can’t be eliminated by the conventional phase cancellation techniques. The Alien crosstalk degrades the performance of the connection by reducing the signal to noise ratio (SNR). Alien crosstalk can be minimized by avoiding installation in which cables are bundled together or run parallel to one another in close distance. The use of patch panels that leave additional space between the racks is recommended. Another way of reducing the Alien crosstalk is by using shielded patch leads.

 

Avoid mixing cable types and bundling them into groups. If there is no other choice but mixing them, leaving at least 15mm space between them is a must for a stable performance.

Keep in mind that beforehand planning and designing is the initial and critical step in installing patch cords. Properly designing the whole cable infrastructure and properly labeling it will eventually save a lot of time and finances. The practices mentioned above will ensure a stable network and a solid ground for future network upgrades.