As an approach to helping building-services engineers reduce the cost of projects, Mark Redfern of Wieland Electric suggests the broader use of structured-wiring systems — and touches on safety issues.
There is constant pressure from end clients to reduce the cost of building services projects, and it’s clear that the specification will make an important contribution to this — not just in terms of the major plant that is specified but also measures that will deliver reduced installation costs.
An example is the use of structured wiring with ‘plug-and-play’ connectivity. This has been shown to deliver savings in installation time in the region of 70%. Even when slightly higher capital costs are taken into account, it is still possible to achieve savings of 30% on final installed cost.
These figures are based on averages across many projects, and clearly there will be some variation from one project to another. For instance, where access is difficult, such as with high-bay lighting, the savings on installation time will be considerably higher because less time will be spent working at height.
In addition, many buildings that use high-bay lighting are factories, warehouses or retail outlets — where any work on the lighting will require scaffolding or the of use mobile elevating work platforms for access. So in a situation where existing lighting is being replaced, anything that saves time will also reduce disruption at ground level.
Additionally, structured wiring enables the installer to make more effective use of multi-skilled operatives. Mechanical operatives working at high level on pipework, for example, can also plug in the connections for the lighting. The plugs are configured so there is only one way to connect them, avoiding the risk of wrong connections being made. Of course, it is essential that connections at the board are made by qualified electricians, but a simple plug-in operation is well within the scope of any multi-skilled operative.
As well as the time savings that can be achieved during installation, structured wiring provides an inherent flexibility that delivers benefits throughout the life of the installation. This is because any subsequent changes to the configuration of lighting or other small power are easily accommodated without the cost and disruption associated with conventional wiring.
Also, the components of a structured wiring system can be re-used, whereas with conventional wiring there is considerable waste during a re-wiring project. Consequently, structured wiring helps to reduce waste and to meet recycling targets.
As with any electrical system there are safety implications to be borne in mind. For example, there have been occasions where we have received requests for male-to-male connectors for plug-and-play ring main circuits. This is something that my company will not supply — for very good reasons. The convention is that only female connectors should be live, and the point of a convention is that if everyone follows it there can’t be any mix-ups.
There are two points to emphasise. The first is that the convention should always be observed. The second is that plug-and-play systems are intended for radial circuits only, not for ring-main circuits. Although there is a huge amount of safety built into the higher quality plug-and-play systems, using them in ring-main circuits could compromise safety under certain circumstances.
Experience shows this is an area of some confusion, possibly because of the need for compliance with BS 61535, whereby connectors intended for permanent installation must comply with IP2X when engaged, and the socket (female) part shall also be IP2X when disengaged (IPX2 is the ‘standard’ European finger test).
The emphasis is on the extra protection for the female connector, but many manufacturers play safe by designing their male connectors to comply with IPX2 as well. There’s nothing wrong with this, of course, but it may have given the impression, erroneously, that live male connectors are acceptable.
Structured-wiring systems have been on the market for some time, and they have continued to evolve. Recent innovations include 6-pole circular structured wiring systems that use a patented coding system for different applications, combined with round connectors to minimise space requirements and facilitate installation through firewalls. There are now also compact ‘micro’ connector systems that have been specifically developed for use with LED lighting in confined spaces such as display cabinets.
Given that such systems are continually being improved, it also makes sense to work with a supplier that can ensure you are specifying the most appropriate structured-wiring system, as well as providing the necessary design and technical support.
Mark Redfern is managing director of Wieland Electric.