Cables

Have you ever wondered what it is that connects computers and networks to one another? Network cable in conjunction with the associated hardware (network switches, hubs, demarcation equipment) is responsible for computers being able to connect and transfer data across intranets (internal network) and the internet. Network cabling today is used for many other purposes besides computer networking. It can be used to carry video for security camera systems as well as video for cable TV and AV (Audio/Visual) applications. Network cabling is also used as control cable in Building Maintenance Systems and Access Control Systems. There are several different types of cables that are used for this purpose, including unshielded twisted pair, shielded twisted pair, fiber optic and coaxial. In some cases, only one type of cable is used in a network, while in other cases, many different types are used. Wireless systems are becoming more and more popular but always remember you still need network cabling for the wireless system. There is still two things that make network cabling better than a wireless network: it is much more secure and reliable.

Understanding Cable Type

Before you can really understand how cable networking works, you need to know about the various cables and how they work. Each cable is different, and the type of cable used for a particular network needs to be related to the size, topology and protocol of the network. Here is a rundown of the cables that are most commonly used for network cabling:

Unshielded/Shielded Twisted Pair - This is the type of cable that is used for many Ethernet networks. There are four sets of pairs of wires inside the cable. There is a thick plastic separator that keeps each pair isolated through the run of cable. Each pair of wires are twisted so there will be no interference from other devices that are on the same network. The pairs are also twisted at different intervals so they will not cause interference between themselves. In an application where there is a lot of Electromagnetic Interference (EMI), such as a mechanical space, you may choose to use shielded twisted pair, which has an outer shielding that adds extra protection from EMI. Category 5e, 6, 6A and 7 are the general choices today. Twisted pair cable is limited to 295' on a horizontal run. Twisted pair cable is used for many applications. Standard station cabling for computers and VOIP phones, wireless access points, network cameras, access control and building maintenance systems are just a few. This is one of the most reliable types of cables, and when used, network failures are less common than when other cables are used.

Fiber Optic - Fiber optic cable is primarily used as backbone cable although it is being used more and more as station cable (think FIOS). By backbone cable I mean it connects Telecommunication Rooms within a space to each other. Fiber optic cable has huge broadband capacities which allow it to carry large amounts of information as super fast speeds. Fiber cables can cover great distances(hundreds of meters) as opposed to copper cable. Because these cables must work so hard and the information travels such distances, there are many layers of protective coating on fiber optic cables. Fiber cables transmit light as opposed to electrical current. Fiber optic cable requires much less power than high speed copper does. Fiber optic cable is a great choice for high speed reliable communications.

Coaxial Cable - Coaxial cable usually falls under the scope of work of the network cabling installation contractor. Coax will be used for the cable television locations within the space you are cabling. The service provider will drop off the outdoor cable at the point of entry. The contractor will run an extension (usually RG-11) to the local telecom closet within the space. The individual station runs(RG-6) will terminate on a splitter to connect to the service cable. The center of this type of cable has a copper conductor and a plastic coating that acts as an insulator between the conductor and the metal shield. This cable is covered with coating, which can vary in thickness. The thicker the coating, the less flexible it is going to be. There are a few types of terminations for coax. Compression, crimp and twist on are the three types of terminations. The best method is compression as long as they are performed correctly. Crimp terminations are also reliable and require the right tool for the particular connector you are using. I would not recommend twist on as they are not reliable and prone to problems. A few types of coax connectors are F connectors, BNC connectors and RCA connector