Cat 5 Cable – A Primer

Usually known as Cat 5, the Category 5 cable is basically a set of 4 twisted pair copper wires which are insulated by an outer jacket. These 24-gauge copper wires terminate in an RJ-45 jack. By and large these cables are unshielded but shielded are available too. It is designed for high signal integrity and mostly used for cabling the computer networks like Ethernet. That is why it is also sometimes referred to as the Ethernet cable. It can also be used for some other signals like ATM, Token ring and basic voice services. Today for all kinds of telephone and network wiring, Cat 5 cable is the most preferred industry standard defined by EIA / TIA – Electronic Industries Association and Telecommunications Industry Association.

The outer cover of Cat 5 cable comes in different colors. The most common being blue. There is also a standard color scheme for the plastic that protects the twisted pairs inside. Orange, blue, green and brown wires are twisted except at the termination point where the connections are made. This twisting basically preserves a high signal-to-noise-ratio by reducing any kind of interference and crosstalk. It can handle frequencies of up to 100 MHz. You can buy this cable of any length that you desire. Standard lengths with an attached RJ-45 jack are also available.

The wire pairs have two main variants. They either have a stranded or a solid core. Stranded cables are suitable for short distances. For example for patch cables needed to connect computer network card to the network jack terminus a stranded core is used. Solid cables can work with longer distances. For runs from the wall termination back to the network patch panel, solid core is used.

One variant of Cat 5 cable is Plenum Cat 5 that has a special outer cover that does not produce any toxic fumes if it burns. These are mainly used to meet fire codes of buildings.

The earlier Cat 3 cable supported data speeds of only 10 megabits per second. While Cat 5 cable can carry data speeds of up to 100 mbps. The enhanced version of Cat 5, is the Cat 5e specification that supports data speeds of 1000 mbps (Gigabit Ethernet). Its performance performance is only recommended for shorter distances that run for a maximum of 100 meters. So it may not be suitable for longer distances for Ethernet networks. Cat 5e is backward compatible with the standard Cat 5 cable.

A more recent cable technology is the Cat 6 cable that has more stringent specifications for system noise and crosstalk. It is expected to support 10 gigabit Ethernet standards, with some limits on the length.

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