Structured cabling - the hidden hero of the IT system

Rosemary McGlashon, 3M

Rosemary McGlashon Cabling is one of the most important elements within any IT network and is one of the biggest IT investments that companies make. Selecting the right cabling system can have a tangible impact on a range of issues, including network performance, the speed at which data can pass through the network, power consumption and even green IT strategies. Therefore, making the right choice of cabling system is too important an issue to be ignored. Rosemary McGlashon shines a light on the often forgotten world of cabling.

Understandably, since cabling is an occasional rather than a regular purchase, most IT managers cannot be expected to be experts in this area, but this does mean that they often need to rely on advice from contractors, consultants, installers and suppliers. This can be dangerous, depending on the quality of the information being distributed. Poor-quality or inadequate cabling systems can bring a network to a standstill.

There have even been occasions where it has been necessary to rip out large sections of structured cabling, due to faults that need to be located and repaired, costing the companies involved vast amounts of money, as well as lost time. These faults may not be immediately obvious, potentially causing the user company considerable disruption at a later date.

The good news is that with a basic understanding of the cabling market and installation issues, IT managers can make more informed choices. The first question is: structured or not? Direct cabling is cheaper, but it is essentially a blind network, without any means to manage or configure it easily. This is particularly important when changes need to be made, for instance switching around connections to end-users, should there be a reorganisation in an office.

When correctly labelled, the patch panel of a structured cabling system makes it easy to see at a glance every connection, so changes can be quickly and easily made, usually without requiring a specialist visit from a third party. Moreover, efficient installation means that any potential EMI or crosstalk options can be minimised, for instance by ensuring specified distances between cables, minimising bend radius and using techniques, such as dual-pathing with diverse routing of cables. Given how often most companies will need to make changes to their cabling systems, however small, structured cabling is these days the sensible option.

Copper v fibre

Most people will be aware that there are two main options for cable material available today: copper and fibre. Within copper, cabling systems complying with Category 5e and Category 6 will probably be the most familiar, as these are the predominant choices for typical enterprise applications. In recent years, copper's capabilities have been extended with the introduction of a standard that enables it to support up to 10 GB/s Ethernet, commonly known as 10G BASE-T. Copper cabling is perfect for most existing desktop applications, but the new standard really pushes its limits: it is hard to argue the case for copper much beyond 10 GB/s, certainly not at the lengths required in most cabling systems. Not only do problems, such as managing EMI, become exacerbated at higher data rates, far greater installation skill is required and the faster the data rate, the more power is required, pushing up operational costs.

Fibre optic cabling, on the other hand, requires a lot less power than copper. Estimates vary, but all are within the range of 10-15 watts per copper port, compared to just 1-5 watts per fibre port. With most companies keeping a close eye on power consumption, or focusing on their green credentials, this is an important consideration. In terms of production, fibre is arguably more environmentally responsible overall: it does not need to be mined and, although it cannot be recycled, it has a much longer lifespan.

Fibre also provides higher density, weighs less and uses less space; plus, unlike copper, it is virtually impossible to 'hack' and is resistant to EMI. Furthermore, since it is a non-conductive material, fibre can also be used in environments where electrical isolation is needed, for instance between buildings. Fibre also does not pose a threat in potentially hazardous environments, for example, in chemical plants where a spark could trigger an explosion.

While it is hard to predict data traffic speeds of the future, fibre's limit is a long way from being reached. Certainly, for any organisation looking at making a long-term cabling investment that will support rising data traffic volumes and transfer speeds for years to come, it makes economical sense to consider the business case for fibre, whether for storage area networks, data centres or even general desktop connections, and particularly for any mission-critical applications.

When fibre is not the best fit

So are there any instances when fibre is not the best choice? Frequently, copper cabling is perfectly adequate for current local area networks (LANs) where the focus is on supporting typical desktop applications. Although the cost of raw copper has risen and fibre is becoming less expensive all the time, copper is still more economical to install and equip with NICs and switches. Furthermore, it typically requires less skill to install, although this advantage is being eroded with 10G BASE-T, which requires far greater precision in order to meet its performance promises.

Fibre is much trickier to get right and currently there are fewer trained expert installers around at the moment, though this is likely to change as fibre becomes more prevalent. Typical errors include incorrect polishing of fibre ends, which can mean that a good contact is not established between two cables, thus impairing performance and since we are talking about a tiny surface area, the chances of getting the curvature wrong are quite high. Fortunately, new product developments are helping to simplify fibre installation and bringing it within reach of more contractors. Examples include no-polish connectors, which eliminate the need to polish fibre ends on site, and integral connector covers that ensure ambient particles - such as dust - do not get into the connection during installation and impair the signal.

Installation issues

However, installation problems are not contained to fibre by any means. Indeed, over the years I have witnessed many network problems caused by poor cabling installation. The issue is that many installers are either not trained at all or have not received regular refresher training over the years. 'Old hands' pass on bad habits to junior members of the team. Understanding the specific installation requirements of different cabling brands is important too. This is why when choosing a cabling system installer, look for the following:

Proven track record in the right technology
This is not just in cabling, but in the format chosen. For instance, if a fibre network is involved, the company should be able to cite reference examples of previous fibre installations.

Recognised training
Ideally this should be a combination of NVCQs, which cover the overall basics of cabling installation, plus specific training from the vendor whose brand of cabling system is being installed. For example, at 3M we run training courses specifically for cabling installers using our Volition cabling accessories and systems. Manufacturers' instructions vary, so training on one brand may not apply to others.

Use of appropriate tools and products
What is available on the market has come a long way in recent years. There are new products, such as the no polish connectors mentioned earlier, that can radically improve consistency of installation. Other products can help to speed up installation time, or reduce the need for specialist tools. When specific tools are required, these should be evident: there is no excuse for installers to use standard craft knives to prepare cables (which can lead to cable nicking, leading to future faults).

Understanding and appreciation of industry standards
These are there for good reason. They provide installers with a guide to best practice, as well as providing the end user with a level of protection. There is a range of industry standards governing cables, but as far as the UK market is concerned, the CENELEC (the European Committee for Electrotechnical Standardisation) standards are probably the most applicable and widely recognised. These standards have been revised in the past couple of years and change regularly, so it is vital that the chosen installer is up to date on recent developments, particularly regarding the main CENELEC 50173 standard, which was updated in 2007 to include specific parts for different environments, for example, the office, industrial environments and data centres.


By using these guidelines and developing a basic understanding of structured cabling, IT managers can ensure they are better equipped to make more informed and accurate decisions about what cabling systems - and most importantly, which installer - best fits their needs.

Rosemary McGlashon is European technical manager, telecommunications, at 3M and has over 20 years experience in structured cabling. Rosemary is currently on the UK national committees for both cabling standards and fibre components, and attends IEC and CENELEC working groups as UK expert for fibre connectors, closures and testing. She is secretary of IEC SC86B working group 6 on optical fibre connectors (