Although recent years have seen major improvements in wireless technology, most office networks still rely, at least to some extent, on copper cabling. But there are many different standards for copper cables which can lead to some confusion. So, what are the various different types and what are their pros and cons?
In the early days of networking, the cables used were coaxial – the same type used to connect a TV aerial. But coaxial cables are bulky and stiff, leading to difficulties with installation and so have gradually been superseded by twisted pair cables, which are far thinner and more flexible. These can also be used for other functions besides networking, such as telephone connections.
This type of standardised connection is known as structured cabling. This is governed by a set of standards that outline how cabling should be laid, what type of cabling should be used and the different topologies that apply.
Cables are generally run from a central point to individual wall outlets. Using a patch panel, each wall outlet can be patched into a network switch, IP or PBX depending on what it’s to be used for. This makes for easy rearrangement of offices without the need to rewire.
Copper data cabling standards are divided into categories, usually abbreviated to ‘Cat’ (Cat3, Cat4, Cat5 and so on). The number refers to the specifications and standards to which the cable was manufactured.
Standards have evolved over the years, which means the higher the category, the faster the speeds (measured in bits) and frequencies (measured in hertz) that the cable can cope with.
The copper data cabling standards are laid out below:
is the oldest standard that was widely adopted, used for many networks in the 1990s. Also known as 10BASE-T, it offers speeds up to 10 Mbps and uses a twisted pair cable.
supports signals up to 20 MHz but was only used for a short time before being overtaken by Cat 5.
increases the number of cables to four pairs – or eight individual wires – and can handle up to 100 MHz. Download speeds are restricted by Ethernet cable length and maximum transmission speeds are measured over 100 meters, after which speed drop off typically begins to occur.
replaced Cat 5 in 2001 and is able to carry Gigabit Ethernet traffic. It can also be used for power over Ethernet applications where electrical power to run devices such as network repeaters is delivered over the Ethernet cable.
have higher standards to prevent cross-talk of data and can handle transmissions up to 250 MHz, known as 1000BASE-TX. However, Cat 6 has a lower maximum length of only 55 metres.
can handle 500 MHz, providing 10GBASE-T and increasing the maximum distance back to 100 metres.
allows frequencies of up to 600 MHz over 100 metres. This means that it can handle Ethernet at speeds of up to 10 Gbps.
is the newest standard. It can operate at up to 2000 MHz but only over distances of up to 36 metres. It’s designed for use in data centres where distances between devices are short, rather than for general office cabling.
Another factor to take into account is whether the cables are shielded. Most network cabling is unshielded twisted pair (UTP) as this is low cost and widely available. However, you can opt for shielded twisted pair (STP) cabling. The latter is preferred in electrically noisy environments – in factories for example – where unshielded cabling could be subject to interference.
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Michael Turner, ICT manager, Downend School