Poor cable installation techniques and lack of experience could create many network problems. Grade of cable or crimping failure could fail the network completely or cause damage in the network that will result in future failures. This article is intended to provide cable installation tips for preventing Physical layer failures.
Twisted pair cable should not be untwisted for more than one-half inch (12.7 mm) before being inserted into the punch-down block. Also, cable should not be stripped more than one inch (25.4 mm) before cable termination. If the ends of the cable are terminated properly – cross talk and data errors will be minimized.
Each patch cord that has been created, should be tested before installation in the proper place. It can be done with a cable tester. If the test is successful, cable should be tested once again after it has been installed. This step ensures that there is no EMI sources that could affect signal nearby. Good example is the fluorescent light that affects the signal from distance less than 3 feet (0.9m). Also, it is necessary to follow grounding requirements for the cable at all times.
Cable could be physically affected in many ways. One way of affecting cable is to bend it. Cable should not be bended more than the bend radius. Each type of cable has its own bend radius – value that represents radius of the maximum arc into which cable can be looped. Exceeding this value will result into data transmission loss or interruption.
At the same time, cable should not be squeezed. If cable has been deformed by squeezing, signal may receive unpredictable data errors.
Cable cannot be stringed too much either. Network deployment crew should leave some slack for the cable. Otherwise data transmission problems would appear.
Cable should be protected if it is deployed across the room or somewhere where rolling chairs or human feet might damage it. This type of wiring is not recommended as constant network solution , but temporary cable should be protected by cable protector cover.
Sometimes the cable is installed in the plenum – area above the tile ceiling or below the subflooring. For this type of installation highly fire resistant cable is required. It is having plenum rated sheath that produces less smoke if burned.
Documentationis an essential part of any project. It is no exception for the network deployment and management. Documentation should be kept in accessible place and should be always up to date. All the modifications in the network should be recorded there as well:
locations of equipment
installation dates
lengths and types of cables
types of data jacks and connectors
cable color labeling
Additionally cables should have labels on them for management. Different purpose cables can have different colors.
Documentation must contain a plan for cabling plant expansion. Telecommunication closets should have enough space for future expansions, while backbone could be replaced by high-speed fiber in the future.
