More and more contractors are turning to pre-wired cable management products in an effort to save time and money and improve the quality of their work. Andrew Brister looks at the pros and cons of off-site fabrication.
With pressure from the Egan Taskforce to improve productivity and quality, contractors could do worse than take a close look at pre-wired cable management systems. It is a relatively new concept, but one which gives safety, quality and cost advantages over on-site fabrication.

Many of the established cable management suppliers have responded to increasing customer demand in this area over the last couple of years by setting up special divisions to increase their capabilities in pre-wired systems.

Mita has its Wired Systems Division, Marshall-Tufflex has formed a Specialised Applications Division and Britmac, part of the Electrium group, also regularly puts its specials arm in to action to meet demands for pre-wired products in commercial building construction.

Dave Haskins, product manager, Britmac Cable Management Systems, puts the reason why there are more and more pre-wired systems in today's construction industry down to the following factors: "The time to install the electrical materials (or lack of it), labour costs and new working practices."

Neil Battery, manager of Mita Wired Systems Division, concurs, putting forward several key advantages of pre-wired systems: "lower costs, reduced installation time, best possible quality and appearance and guaranteed safety."

With fulsome praise from the manufacturers and seemingly nothing but benefits for the contractor, why does the whole industry not turn on to pre-wired systems? It has to be said that such solutions are better suited to larger installations: offices, hospitals, factories, and schools can all benefit from pre-wired systems, anywhere in fact where there is a lot of repetitive wiring, particularly in fast-track installations.

Another application area is where the needs of the customer may change over time: pre-wired cable management solutions can be easily reconfigured to take account of changes in office layout.

Safety is another factor. Pre-wired systems – whether perimeter trunking with standard accessories fitted and wired to specific requirements or bespoke power distribution modules – are all fully electrically tested to relevant standards before they leave the factory.

Cutting trunking under site conditions is simple in theory, but far less easy in practice. On site preparations can therefore lead to an inconsistent and less than perfect appearance. Factory-assembled units, by contrast, are prepared in ideal, standardised conditions that will ensure the final appearance is 100% as it should be with no inconsistencies.

The benefit of the reduced installation time that pre-wired trunking offers is advantageous to both the installer and the final customer. Ready-made modules are easily fitted and connected in the minimum of time, allowing the contractor to get off site quickly and enable normal operation to be resumed on the customer's premises.

Britmac's Dave Haskins says demand from clients is in the following areas:

  • floor outlet boxes used in conjunction with raised access floor systems and utilising 63 A busbar track;

  • bench/desk modules used in conjunction with raised access floor systems and utilising floor grommets and 63 A busbar track;

  • power poles;

  • pvc dado trunking incorporating 63 A busbar track;

  • 25/40 A lighting busbar track.

    An installation of Mita equipment by contractor Morris Spottiswood Group at West Calder High School illustrates the approach. The school wanted to convert one of its existing buildings into a computer laboratory and needed it done in just ten days. By using pre-wired trunking modules, designed and manufactured to fit the workbenches on which they were to be installed, the project was completed well within the timescale.

    Mita's Neil Battery argues that it would have been very difficult to match the quality of the installation if the contractor had opted for on-site fabrication. There is not doubt that time savings were made by relegating simple tasks to the factory, leaving skilled operatives to get on with more demanding matters.

    Cynical contractors will ask: what about the increased capital cost? It is true that reduced cost is not the first thing that springs to mind when receiving quotes for pre-wired systems but the savings in labour cost quickly pay for themselves. Mita's Neil Battery estimates that savings can be be high as 30% over traditional on-site fabrication.

    Perhaps the office, with its regular changes in layout, offers the greatest potential for widespread application. In a recent application for a major oil company Marshall-Tufflex needed to provide a cable management solution which would allow the end user to change the position of demountable partitions used to separate office areas within the open plan environment.

    Consulting building services engineer Wallace, Whittle & Partners required a modular system which would allow it to demount the section of trunking which fitted into each bay window. This would facilitate the reconfiguration of the cable management system in the event of future changes in the office layout and the positioning of the partitions.

    Marshall-Tufflex preassembled 2·4 m lengths of Sterling Profile 4 with the required data and power accessories. In order to cope with the high integrity earthing problems created by the large amount of computer equipment being used in the building, these units featured a busbar assembly with electromagnetic screening.

    Once on site, all the contractor had to do was to install these sections to the wall and plug in the services which were dropped down from a ceiling-mounted busbar assembly via flexible conduit contained within the wall. Once the trunking was in place, the data and communication services were wired into the outer compartments of the trunking using the accessory boxes installed. Job done.

    According to Stuart Mann, Marshall-Tufflex's senior technical co-ordinator: "As specifiers are looking to contain costs and produce a more effective cable management solution we are finding a growing demand for the services offered by our Specialised Applications Division. The ability to provide custom-designed systems which can meet the client's exact requirements is vitally important for securing major contracts in today's competitive environment."

    The final word goes to Mita's Neil Battery: "It should be emphasised that pre-wired systems are not meant to short change the contractor. Rather they can add to their reputation, guaranteeing a high quality installation and exact safety requirements. In addition, skilled personnel will not be detained on a project for longer than is absolutely necessary."

    Marshall Tufflex has introduced the Sterling Mono Plus and Sterling Mono to its trunking ranges. Mono Plus is a 140mm x 50mm three compartment design with two divider fillets clipping into place either side of the accessory box. Mono is smaller - 100 mm x 50 mm - and can be divided into two compartments.

    Ackermann has launched Acklaim, a range of multi-gang furniture designed to satisfy BS 6396. It claims that Acklaim is the slimmest, shallowest and most versatile range of socket outlets for offices, call centres and dealing rooms.

    Floorplan Systems introduces a new system of managing underfloor cables, the Takiron floor. It is a 500 mm modular system built up from triangular sections and will incorporate most electrical systems.

    Hamilton Litestat's System 45 garden power/communication posts are weatherproof to IP55. The products feature interchangeable modules which allow combinations of power, audio jacks and telephone outlets, as well as devices such as timers. The outlets for power etc clip neatly into the top of a 750 mm high post.

    Salamande has introduced a four compartment version of its Classic floor boxes. The Classic SC4 has four dedicated services outlet plates and an option to accommodate four 20-25 mm conduits for ducting. The outlets will provide standard and clean earth supplies for power, voice and data installations.

    Adaptaflex now has hinged T and Y pieces for its range of fittings for non-metallic corrugated flexible conduits. They simply snap around the conduit providing an unrestricted bore for ease of wiring. The fittings are available in black as standard.

    The Alphel DB2000 modular system is said to make it simpler to install customer distribution systems to store checkouts. Multiple parallel mounted DB2000 runs are increasingly being used in stores such as Marks & Spencer and major supermarket chains. Outlets available include power, off standard sockets, foot control switches and remote mounted CAT 5 data units.

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    Electrical and Mechanical Contractor