Twisted pair cables



Twisted pair cables are pair of wires twisted around each other form a twisted pair cable to reduce cross-talk. A number of twisted pair wires are placed inside a protective sheath to from a cable. Whenever signal passes through a wire, an electromagnetic field is generated around it called as a loop. When other wires come into the loop, the signals pass onto them. Thus, the signals of both the wires get jumbled with each other. This phenomenon us known as cross-talk. To avoid this, two wires are wounded across each other where one wire acts as a ground and absorbs the electromagnetic field of the other wire. this reduces the problem of cross-talk which is an internal noise.


There are two types of twisted pair cables

  • Un-shielded twisted pair (UTP)
  • shielded twisted pair (STP)

Un-shielded twisted pair (UTP)

A pair of un-shielded wires wound around each other is know as UTP. At UTP is a pair of copper wires wound by plastic insulator. UTP is the cheapest from of cables available for networking purposes. It is mostly used in local Area Network (LAN) environments. The installation cost of the cable is very cheap as it is easy to install.

The cables are divided into different categories :-

  • Category 5 – Defines a cable that can carry data up to 100 Mbps. The signaling frequency of this cable is up to 100 MHz. This type of cable is primarily used in today’s networking environment.
  •  Category 5e – Defines a cables that can carry data up to 1000 Mbps with a signaling frequency of 100 MHz. It is used to connect computer, hubs, switches and printer servers.
  • Category 6 – Defines a 4-pair cable that provides an improved performance as compared to cat 5e. Data is transferred at the rate of 1000 Mbps with a signaling frequency of 250 MHz.
  • Category 6a – Support 10 Gbps applications with a signaling frequency of 500 MHz. 
  • Category 7 – Defines a fully shielded twisted pair cable that operates at the signal frequency of 600 MHz. Fully shielded means  all the four pairs of a cable have additional shield over them.

Advantages of UTP

  • Cheapest from of cable available for networking purposes.
  • easy to handle and install.

Disadvantages of UTP

  • highly prone to external interference like EMI and RFI.
  • Highly prone to cross-talk.
  • Unable to provide secure transmission of data.


shielded twisted pair (STP)

A pair of wires wound around each other and each pair is placed inside a protective foll wrap to protect it from cross-talk. These wires are placed in an outer copper braid to protect it from external interference. STP is less susceptible to external interference as the shielding absorbs all the EMI and RFI signals. STP can be used in environments that are near electrical units and radio towers. STP is cheaper than fiber optical cables but more expensive than UTP. These cables are also suitable for places that are sensitive to electrical current. An example of this would be laboratories. High security buildings with various types of equipment will also benefit by using an STP cable.


Advantages of STP

  • Better protection from cross-talk.
  • Better protection from external interference.
  • secured data transmission.

Disadvantages of UTP

  • Costlier than UTP.
  • Difficult to install as co,pared to UTP.


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