Twisted-pair cables vs. Fiber-optic

Fiber Optic - Twisted pair Cable Network

In today’s networking technology, two types of cables are most common. The most abundant one is Twisted-Pair cables with a copper core. These cables are generally cheap and the installation is relatively easy. The second type is Fiber-optic which is more expensive but it has the advantage of higher transmission speed

More will come about the technical features of these types of network media.

Twisted-pair cables

The twisted-pair cable consists of multiple, individually insulated wires that are twisted together in pairs. For a better performance, a metallic shield is wrapped around the twisted pairs, as the name suggests, to make a shielded twisted-pair (STP). Another type is Unshielded twisted-pair (UTP) which doesn’t have the aforementioned shield around the cores.

Let’s take a look at why these cables are twisted. We know that an electric current creates an electromagnetic field around the cable. The more powerful the current is, the wider the electromagnetic field around the cable will be.

Now when two wires are in proximity to each other, their electromagnetic fields will interfere with each other, affecting the flow of the current and in sever cases, interrupting it. This technically is called Crosstalk.

To solve this issue, engineers have found out that twisting wires in pairs (with different twist-per-length radio for each pair) will greatly reduce the crosstalk. This will also degrade the electromagnetic interference that’s caused by power cables running in proximity of network cables in the building.


Twisted-pair categories

There are couple of categories for Twisted-pair cables:

Category 1: It has two twisted-pairs (four wires) inside. The cables in this category are generally suited for transmitting voice communication not for data. The oldest example of these kinds of cables is UTP which is frequently referred to as POTS or Plain Old Telephone Service.

This was the standard & predominant cable throughout the North American telephone system until 1983. POTS cables still exist in parts of the Public Switched Telephone Network (PSTN).

Category 2: Has four twisted-pairs (eight wires) in it. This cable is suitable for transmission speed of up to 4Mbps.

Category 3: Comes with four twisted-pairs (eight wires). Wires are twisted three times per foot. These cables are able to properly supply a transmission speed of 10Mbps. This was a popular choice since the mid-80s.

Category 4: The cables in this category have four twisted-pairs (eight wires) and are rated for 16Mbps of data delivery.

Category 5: Probably the most common media used for LAN networks. Also known as Cat-5, has four twisted-pairs (eight wires) and is capable of transmitting data up to 100Mbps.

Category 6: This category has become popular since a few years ago and taken over the Cat-5 cables. It also holds four twisted-pairs (eight wires) and can send/receive data with a speed of up to 1000Mbps.

Twisted pair connectors

The standard connector used for Twisted-pair cables is commonly called Registered Jack (RJ) connectors. As the picture shows, these connectors have 8 pins and each pin will punch and hold down one wire.

Now you might have seen that there’s a similar but smaller connector attached to your telephone line, where it plugs into your phone. These connectors are also RJ but they can only hold four wires under their pins.


The connector that is used for network cables is called RJ45 and the smaller connectors used for telephone lines are called RJ54. These connectors can be punched with a particular pliers called Crimper.

Fiber Optic cables

Another type of the cables that is being frequently used in today’s computer networking is Fiber-optic cables. The core part of these cables is built of glass or transparent plastic.

Rather than electricity, these type cables use light or laser beams for transmitting data. Fiber-optic cables normally come in a pair of fibers. One fiber is used for sending and the other is for receiving.

Fiber-optic cables use different types of connectors, but the two most popular connectors are the Subscriber Connector (SC) and Lucent Connector (LC). There are also two types of optic fibers available. Fist type is known as Multi-Mode (MM) and the other one is called Single Mode (SM).

MM fibers are cheaper than SM fibers. MM fibers use light for data transmission and send data to a short distance (500 meters). SM fibers on the other hand, use laser beam for transmitting signal and are capable of sending data to much longer distances (more than 10KM).


Ethernet cable types

Naming Ethernet cables involves using the following format: N<Signal>K

  • N denotes the rate of the signaling in megabits/sec.
  • <Signal> shows the type of signaling, which is baseband or broadband.
  • K is a unique identifier for that specific Ethernet cabling scheme

Let’s show an example to understand it better. For instance, the first two digits in 10BaseT cable means the speed is 10Mbps. Based indicates this cable is using Baseband signaling method. The last letter “T” shows this is a Twisted-pair cable.

In the below table you can find the most common Ethernet cables with the maximum speed and maximum distance they support:

Cable types

We have other types of Ethernet cables and we’ll go through them later in another article.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.