radio frequency interference (RFI). To further reduce crosstalk between the pairs in UTP
cable, the number of twists in the wire pairs varies. Both UTP and shielded twisted-pair
(STP) cable must follow precise specifications regarding how many twists or braids are
permitted per meter.
UTP cable is used in a variety of types of networks. When used as a network medium,
UTP cable has four pairs of either 22- or 24-gauge copper wire. UTP used as a network
medium has an impedance of 100 ohms, differentiating it from other types of twistedpair
wiring, such as that used for telephone wiring. Because UTP cable has an external
diameter of approximately 0.43 cm, or 0.17 inches, its small size can be advantageous
during installation. Also, because UTP can be used with most major network architectures,
it continues to grow in popularity.
Here are the categories of UTP cable: