As a starting point, it is useful to think of a structured wiring system in terms of a house’s electrical system. Electricity flows into the house through a main power cable. This cable connects to a circuit breaker box, where it is separated and sent down smaller electric lines. These lines wind their way through your walls, ultimately ending at power outlets throughout your home. You then plug devices into the outlets and use them.
In a structured wiring system, all external data lines (such as cable television, telephone, or internet) come into the house and are connected directly to a central control box. This box is usually the size of a large electric circuit breaker panel, and is placed in a similar location, such as in the basement or a utility closet.
Within the control box, each incoming signal is split and sent down wires to multiple rooms in the house. In a good-quality central control box, the splitter will also contain a signal amplifier. This device makes sure each outgoing signal is as strong as the single incoming signal. Without an amplifier, the power of the incoming signal gets split among each outgoing wire, often resulting in significant performance loss. In layman’s terms, this means a snowy TV or staticy phone line.
From the control box, bundles of wires run through the walls of the house to different rooms. With a good structured wiring package, these wires will be installed in a “home run” or “star topology” configuration. This means that each set of wires runs to only one outlet. This is in contrast to “daisy chaining”, which means one line goes first to your kitchen, then to your living room, then to your bedroom. Although daisy chaining is less expensive, it introduces problems as the signal quality in your bedroom (the last stop) is much poorer than that in your kitchen (the first stop).
The wires included in the bundle vary by manufacturer, but you should look for at least two coaxial cables of RG-6 quality and two twisted pair cables of CAT-5 quality.
“Coaxial cable” is just a fancy name for the typical black cable you use for purposes such as connecting your VCR to your television — the type with the copper wire sticking out the end and the annoying screw attachment. RG-6 is a rating of quality; some manufacturers use RG-59 or lower grades, but you should avoid these as your picture quality will not be as good.
“Twisted pair” is another fancy name, referring to the telephone cable that runs to the phone jack on your wall. It is called twisted pair because it consists of two wires that are twisted around each other. (As strange as it may seem, the twisting actually improves the quality of the signal!) CAT-5 is a an abbreviation for Category Five, another indicator of quality. Generally higher numbers indicate better quality, though CAT-5e is one step better than CAT-5.
These cables are often bundled together and covered with a plastic coating. This is advantageous as a bundle is easier to install, and the stronger wires (RG-6) help to protect the weaker wires (CAT-5) during the installation process. (With good-quality wires, there will be no loss of performance or interference from bundling.) This bundle is run through the walls of your house, and terminated at a wall plate. These plates are about the same size as a normal wall face plate.
Depending on the wires included in the bundle, it will have two to eight different outlets. For example, with the four-wire bundle described above, the wall plate would have two cable jacks and two phone jacks.