unshielded twisted-pair (UTP) cabling

Definition of unshielded twisted-pair (UTP) cabling in The Network Encyclopedia.

What is Unshielded twisted-pair (UTP) cabling?

Unshielded Twisted-pair Cabling, or UTP cabling, is a Twisted-pair cabling with no internal shielding. The outer insulating jacket protects the cable from physical stress or damage but does not shield the cable from electromagnetic interference (EMI). Unshielded twisted-pair cabling (UTP) is the most common form of network cabling for workgroups and departmental local area networks (LANs) because of its low cost, flexibility, and good performance.

UTP cabling has an impedance of approximately 100 ohms and comes in various grades or categories based on data transmission capabilities, as shown in the following table. Category 5 cabling is the most popular form of UTP cabling in 10/100-Mbps Ethernet workgroup or departmental LANs. No agreed standards exist above category 5, but many manufacturers offer UTP cabling certified for transmission rates up to 350 MHz or higher.

UTP Cabling Categories

Category Use
Category 1
Analog voice grade
Category 2
Digital voice transmissions up to 4 Mbps
Category 3
Digital transmissions up to 10 Mbps
Category 4
Digital transmissions up to 16 Mbps
Category 5
Digital transmissions up to 100 Mbps

To ensure that category 5 UTP cabling performs effectively, you should also use certified category 5 wall plates, connectors, and patch panels. The patch panel or wall plate connections should be untwisted no more than 0.5 inches; also try to keep cabling away from fluorescent lights, motors, and other sources of EMI. Do not bend the cable sharply - the radius of a bend should not be less than 10 times the diameter of the cable. Finally, avoid pulling cable wraps too tightly or crushing the cables in any way.

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