Structured cabling design and installation are governed by a set of standards that specify wiring data centres, offices, and apartment buildings for data or voice communications using various kinds of cable, most commonly category 5e (CAT-5e), category 6 (CAT-6), and fibre optic cabling and modular connectors. These standards define how to lay the cabling in various topologies in order to meet the needs of the customer, typically using a central patch panel (which is normally 19-inch rack-mounted), from where each modular connection can be used as needed. Each outlet is then patched into a network switch (normally also rack-mounted) for network use or into an IP or PBX (private branch exchange) telephone system patch panel.
Cabling standards demand that all eight conductors in Cat5/5e/6 cable are connected, resisting the temptation to ‘double-up’ or use one cable for both voice and data. IP phone systems, however, can run the telephone and the computer on the same wires.
Optical fibre (or “fibre optic”) refers to the medium and the technology associated with the transmission of information as light pulses along with a glass or plastic strand or fibre. Optical fibre carries much more information than conventional copper wire and is in general not subject to electromagnetic interference and the need to retransmit signals. Most telephone company long-distance lines are now made of optical fibre.
Transmission over an optical fibre cable requires repeaters at distance intervals. The glass fibre requires more protection within an outer cable than copper. For these reasons and because the installation of any new cabling is labour-intensive, few communities have installed optical fibre cables from the phone company’s branch office to local customers (known as local loops). A type of fibre known as re is used for longer distances; multimode is used for shorter distances.