|  | 9.3 | Basics of Cable Installation
| 9.3.1 | Basics of installing UTP cable
To connect cables as shown in Figure to jacks, follow these steps: Strip back only as much of the cable's jacket as is required to terminate the wires. The more wire you expose, the poorer the connection, and the greater the signal loss. Make sure that you maintain the twists in each pair of wires, as much as possible, to the point of termination. It is the twisting of the wires that produces the cancellation that is needed to prevent radio and electromagnetic interference. For CAT 4 UTP, the maximum amount of untwisted wire that is allowed is 25 mm. For CAT 5 UTP, the maximum amount of untwisted wire that is allowed is 13 mm. If you must bend the cable in order to route it, be sure to maintain a bend radius that is four times the diameter of the cable. Never bend cable to the extent that it exceeds a 90º angle. Avoid stretching cable when you are handling it. If you exceed 11.3 kg of pull, the wires inside the cable can untwist, and as you have already learned, that can lead to interference and crosstalk. If multiple cables must run over the same path, use cable ties to cinch them together. Position the ties at random intervals, then tighten them carefully. Never tighten the ties too much, as that can damage the cables. Minimize the twisting of the cable jackets. If you twist them too much, the jackets may tear. Never allow cables to be pinched or kinked. If this occurs, data throughput will be reduced, and the LAN will operate at less than optimal capacity. Never be stingy when determining the amount of cable that you will need for running cable. It is important to leave ample slack. Remember, a few feet of extra cable is a small price to pay to avoid having to redo a cable run because of problems caused by stretched cable. Most cable installers avoid this problem by leaving enough slack for the cable to reach the floor, and extend another 60-90 cm at both ends. Most installers follow the practice of leaving what is called a service coil, which is simply a couple of extra meters of cable left coiled up inside the ceiling, or in another out-of-the-way location. When securing the cable, use appropriate and recommended techniques for using cable ties, cable support bars, wire management panels, and releasable Velcro straps. Never use a staple gun to position cables. Staples can pierce the jacket, causing loss of connection. As always, remember the do's and don'ts for installing cable.
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