Now that we have the wire, something must connect it to our PC clients and servers following some basic wiring layouts and rules. Our emphasis here is on twisted pair wiring because it currently dominates the wiring used in facilities today for both LAN and telephone wiring. UTP wire in wide use is typically 19-gauge to 26-gauge. Older telephone premises wire is 24-gauge to 26-gauge (AWG) with commonly two twists per foot, while newer wiring is CAT-5 or CAT-5+.
Twisting wire pairs cancels out radiated energy from current flowing in any one wire by the radiated energy from the same current flowing back in the return wire of the same pair. Radiated energy is called Electromagnetic Radiation (EMR). Twisting effectively and inexpensively minimizes crosstalk between adjacent pairs in a multi-pair cable. Twisting also makes the wire pairs less susceptible to external noise. The noise is coupled equally into each wire in a pair, causing the noise to cancel out when the wires are properly terminated. At voice frequencies, each pair appears to be balanced, e.g., equal electrical energy is emitted from each wire within the pair to any point outside the pair of wires.
Wire can be either plenum or non-plenum cabling. Plenum cable uses Teflon or other high-temperature material for outside electrical insulation as opposed to non-plenum wire that uses PVC material. LAN wiring hardware is designed to work with specific cabling from both the electrical and mechanical viewpoints.
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