twisted pair

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twisted pair

[′twis·təd ′per]
A cable composed of two small insulated conductors twisted together without a common covering. Also known as copper pair.

twisted pair

twisted pair
Two insulated electrical conductors, twisted together without a common covering.

twisted pair

A type of cable in which pairs of conductors are twisted together to randomise possible cross-talk from nearby wiring. Inadequate twisting is detectable using modern cable testing instruments.

twisted pair

A thin-diameter wire (22 to 26 gauge) commonly used for telephone and network cabling. The wires are twisted around each other to minimize interference from other twisted pairs in the cable (Alexander Graham Bell invented this and was awarded a patent for it in 1881). Twisted pairs have less bandwidth than coaxial cable or optical fiber.

Twisted pair cables are available unshielded (UTP) or shielded (STP), with UTP being the most common. STP is used in noisy environments where the shield around each of the wire pairs, plus an overall shield, protects against excessive electromagnetic interference. A variation of STP, known as ScTP for "screened twisted pair" or FTP for "foil twisted pair," uses only the overall shield and provides more protection than UTP, but not as much as STP.

Standed and Solid
Both UTP and STP come in stranded and solid wire varieties. The stranded wire is the most common and is also very flexible for bending around corners. Solid wire has less attenuation and spans longer distances, but is less flexible than stranded and cannot be repeatedly bent.

   Cable      Band-      Data#  Type       Width      Rate

 1  UTP       Analog voice

 2  UTP                 1 Mbps

 3  UTP/STP   16 MHz,   4 Mbps

 4  UTP/STP   20 MHz,  16 Mbps

 5  UTP/STP  100 MHz, 100 Mbps

 5e UTP/STP  100 MHz,   1 Gbps

 6  UTP/STP  200 MHz,  10 Gbps (<10 m)

 6a UTP/STP  500 MHz,  10 Gbps (>10 m)

 7  STP      600 MHz   10 Gbps

 7a STP     1000 MHz   40 Gbps (<15 m)

Shielded and Unshielded Twisted Pairs
The metal shrouds on shielded cable add protection against external interference.

The Twisted Pair