Better ways to skin a CAT

There can be few sectors within the contracting industry that are currently as dynamic and diverse as the voice and data market. The UK’s ceaseless appetite for creating, transmitting and storing data means that the sector is set to grow for the foreseeable future, and technology is following this demand by evolving and developing faster, better systems apace.

It’s a market that’s not without challenges, given the rate of development as technology responds to demands to move increasing amounts of data more quickly, use the internet for telephony and distribute power over data cabling. Power over Ethernet (PoE) is already being used in many applications. PoE provides power (usually DC) over twisted pair cable, normally used purely for voice, data and video. DC enables power for devices such as IP telephones, but the number of new applications is increasing.

On site, the challenges are no fewer. Not only does one have to consider which category of cabling to use, but also the type of structured cabling and what kind of cable management system is best for the job. And don’t forget the client – their initial needs might not be what’s actually required, so always get a tight and realistic specification agreed that caters for the future.

Like any sector, voice and data cabling has its standards, and it is worth reminding ourselves what they are and what they mean. Choosing the right data cabling category is important, because to get it wrong could mean making a business’ computer system obsolete in a matter of months, or the client making an investment upon which they will never really get a return. An ‘all singing, all dancing’ installation is not generally required for the average small to medium sized company.

Cables come in a number of categories, defined largely by their performance in transmitting data. It is widely acknowledged that Cat 5e, where the e stands for enhanced, is cost effective, easy to install and supports applications including Gigabit Ethernet. If 10/100/1000 Ethernet is required, the 100 MHz bandwidth will be acceptable.

Cat 6 costs a little more. It also takes longer to install, but has greater bandwidth (200 MHz, tested to 250 MHz). However, this is not normally enough to support 10-Gigabit Ethernet (10GBase-T) beyond about 50 m. Augmented Cat 6 is the unshielded twisted pair (UTP) cabling platform being developed to support 10GBase-T, but its use must be considered quite specialised, although it is only a matter of time and technology until it becomes the everyday norm.

At the top end is Cat 7, which is an expensive and complicated fully shielded system, but boasts a 600 MHz bandwidth. Not surprisingly, only a small amount has been installed so far. As with any job, a balance between budget, performance and technology is crucial in determining the best choice for any specific application.

At present, all the talk is about Cat 6. It typically costs only 10% more than Cat 5e to purchase, but is considerably more difficult to install and, under a well-written specification, should attract a manufacturer-underwritten guarantee of 25 years.

However, adopting a policy of consistently specifying Cat 6 can be difficult, especially in incremental installations where the density of existing Cat 5e outlets is being increased, perhaps owing to earlier under provisioning. There is still a strong market for Cat 5e, quite possibly as a result of the need for this type of enhancement.

The history of Cat 3, 4, 5 and 5e, together with the increasing bandwidth requirements of applications suggests Cat 6 may be a better investment than Cat 5e for new-build installations. In its lifetime, the cabling will probably support several generations of equipment. The capital cost is higher, but the long-term cost of ownership may well be lower than Cat 5e.

On screen

It is worth reiterating the main types of cable used in structured cabling installations: UTP, screened twisted pair (STP) and fibre optic. Most computer networks are cabled using UTP, as it is a versatile product capable of supporting most system and network protocols.

STP tends to be used in place of UTP in environments where there is high ambient noise or electromagnetic interference such as in a hospital. Fibre optic cable is specified for high speed, high bandwith applications and is available in two formats – single mode, widely used in telephony and multimode suitable for network communications. Multimode fibre is capable of handling large bandwith, with high-speed data transmission. It is compact and easy to install.

Having made the choice of category and type of cabling, the question of managing the cable installation arises. Depending on the existing cable management systems, it may be a question of ameliorating existing trunking or underfloor systems, or starting from scratch if it’s a new build or total refurbishment.

Two/three compartment dado trunking is the accepted way of routing data and power around offices and buildings. It is segregated so that, usually, the power cable is contained within the central compartment, with data cable in the top and bottom, leaving the central compartment for easy installation of the accessories.

This is an attractive solution that can meet the structured cabling requirements for Cat 5e and Cat 6. Cat 6e has still to be ratified, but when it is, it will have significant implications for cable management to the workstation. However, careful management of data around corners is crucial, whether external or internal. The bend radius is critical in avoiding data corruption or loss. For the same reason, the bend radii at the data cable terminations to the data modules (located where required along the trunking) are also critical. Typically, the bend radius must not be less than 4 x cable diameter after installation.

Box clever

In terms of the invisible systems, screeded floor arrangements used to be very popular. Here, the various cables are laid in trunking set into the floor to pre-wired floorboxes. However, today this is considered to lack flexibility, especially when office layouts are constantly changing. In addition, modern office design tends to favour raised floors.

Raised floor systems are flexible and versatile, with power running in track with tap-offs located at strategic positions. There are two ways of achieving power and data to the workstation. The first is via floorboxes. The second is to use a desk module (Deskpod). Cable exits the raised floor through a grommet and joins the desk via the module. Fused or unfused modules can be provided with clean earth, power/data points, and even satellite communications.

For more complex installations where there is a high concentration of workstations, it’s prudent to use a hub arrangement, such as Ackermann’s Spider unit. This comprises a galvanised housing, power unit with MCB/RCBO protection and data hub. Each hub feeds up to eight desks. Power and data are fed to the underfloor hub.

In terms of installation, an essential aspect to consider is the number of data points. Allow for a 20% over-capacity for a degree of future-proofing.