There are different category cables in today’s market, and the number of the various types keeps growing with new developments. Category cables are numbered, as well as marked with a letter per their standard (for example Cat5e, Cat6a) as applicable. There are also standard, solid, shield and unshielded cables. So how does one choose the right category cable for an installation?
The difference in category cables is not a visual one, though the specifications of each cable should be printed on the actual cable. Each cable is designed to support different need. See table below for clarifications.
What does it all mean? The higher the category number is, the faster the speed and Mhz of the wire. A higher category number adds isolation between the wires and eliminates crosstalk (XT) better than the lower category number.
For best results and to support the desired speeds, not only is the use of the appropriate cable important, but also the use of connections that can carry these speeds. Otherwise there may be mixed or pure results.
To eliminate interference and allow faster speeds, wire twisting and isolation are needed. Cable twisting was developed in 1881 by Alexander Graham Bell for use on telephone wires that were run parallel to power lines. Bell discovered that by twisting the cable every 3-4 utility poles, interference is reduced and range is increased. The method of twisted pair became the basis for all Ethernet cables in order to eliminate interference between internal wires (XT), and external wires (AXT).
The two key differences between Cat5 and Cat6 cables include the number of twists per centimeter throughout the wire and the sheath thickness.
Typically, a Cat5/Cat5e cable has 1 ½ – 2 twists per centimeter and a Cat6 cable has 2 or more twists per centimeter. Each color pair has different twist lengths. This method is designed to eliminate any two twists to ever align.
A nylon spline may or may not be introduced in Cat5 and Cat6 cables. While it is not required to have a nylon spline, it helps reduce crosstalk in the wire. A thicker sheath protects against near end crosstalk (NEXT) and alien crosstalk (AXT), both of which may occur more frequently as the frequency (Mhz) increases.
Shielded (STP) vs. Unshielded (UTP)
To further protect the cable from interference, shielding is used. Unshielded twisted pair cables are suitable for use outside the walls, such as connecting your computer to the wall. A shielded cable is needed for high interference areas, outdoors and inside walls.
Ethernet cables are typically shielded by putting some type of shield around each pair of wires. This keeps the pairs from internal crosstalk.
Solid vs. stranded
The copper conductor in the pairs can be solid or stranded. An Ethernet cable with a solid conductor encloses a single piece of copper, while a cable with a stranded conductor encloses a bunch of twisted copper cables.
The main difference in application between the two is the cables’ flexibility. A stranded cable is more flexible and can be used outside the wall and at the reach of the end user. It can be easily bent and moved around with no harm to it. A solid cable lacks the flexibility of the stranded cable, which makes it ideal for use inside walls and for permanent installations as well as outdoor ones.