Modular wiring devices - an introduction

Among the strongest trends in the domestic housing and small commercial building sectors is the ever-increasing demand for more socket outlets and control points, higher specifications and greater 'plug and play' functionality - all with style. Changes in legislation in terms of safety (earth bonding, extra RCD protection) and the environment (energy saving), as well as evolving building and architectural practises are also having an effect on the market for wiring devices.

A 2003 survey, commissioned by Voltimum UK Manufacturing Partner Novar Intelligent Building Systems (IBS), whose brands include MK Electric, Friedland, Bardic and ADE Security, of just over 1000 potential home buyers, showed a number of interesting trends. Importantly, the survey showed that that most home buyers rate security measures and an adequate number of electrical sockets for TV, DVD, Hi-Fi, PCs and so on, as more important features that influence their buying decisions, than floor coverings and soft furnishings. The research also revealed that for those planning to move into a newly built home, 86% rated security measures such as burglar alarms as an important factor in their purchase decision. Moreover, 69% wanted more electrical sockets to cater for all their electrical appliances. Moreover, this is a growing trend.

Today, therefore, the requirement is for wiring accessories - switches, switch sockets, dimmers and the like - being asked to look after more and more electrical / electronic equipment. Typical examples include computers and peripherals, AV, media and kitchen equipment, modern household controls such as security, lighting and H & V, as well as hobby equipment. Moreover, people want all these extra devices - sockets, light switches / remote dimmers and TV / 'phone outlets - exactly where they are wanted, not just tucked away in a corner somewhere.

All this has led to the major wiring accessories manufacturers providing good-looking and contemporary wiring accessories with greater 'intelligence' in-built. Not only do modern devices have to be stylish, they also have to match decors and other devices in terms of shape, size, style and finish.

Opportunities for electrical contractors:

For electrical contractors, these trends present many opportunities. Not only are both the public sector and private housing markets still holding up despite dire predictions, there is also a lot more electrical work involved. But what installation parameters need to be considered? At first fix stage, the types of cable, data, coaxial, power and lighting needs all need to be established, as do the number of sockets and control devices required, plus room for future expansion and/or upgrades. EMC considerations (if any) need to be worked out, as do segregation issues - both far more important today than they ever were previously. For RF devices such as TV and radio (AM / FM / satellite or all three), the type of cabling involved will need to be carefully considered as well.

The choice of the actual switching or control devices will depend upon a number of factors including function (power, non-power and control only). Traditionally, the result has typically been an ugly and often inconvenient mishmash of various sockets and control devices littered around a room - sometimes a nightmare to wire as well. Today, one increasingly common answer to the problem is to use modular wiring devices. Basically an extension of the commercial grid system, these have been evolved specifically to address all these issues and most major manufacturers now supply them. Modular wiring devices can combine all the required functions - power and non-power switching, plus the required control - in one stylish and unified housing. Modular devices also do away with the need for untidy and potentially dangerous extension leads.

There will be a range of style, finish and colour options to choose from so as to match virtually any décor. Ranges of backbox sizes, easily changed front plates and various mounting frames allow any application to be catered for, all with flexibility and with simple wiring and fixing. Combination plates, such as those supplied by MK Electric, meet modern multimedia requirements in one neat and unobtrusive data, TV, satellite and power combination plate. Euro data front plates are available, as are Cat 5 / 5E and ISDN modules.

'Smart homes':

Many of the latest developments in the so-called 'intelligent (or smart) home' were made first in mainland Europe but are finding their way here. A typical reason for smart home control is comfort - setting the right lights for mood without getting up, for example. Typically, a central control unit runs the whole system, based on information from peripherals, and on pre-set instructions. Commands can be sent through a two-wire fieldbus system, power lines, telephone lines or fibre-optic cables. Intelligent peripherals manage a variety of local tasks and functions, while the central unit acts as a supervisor. The challenge of integrating many applications, creating quite complex systems with sometimes hundreds of user controllable parameters is critical. Special human machine interfaces (HMI) are often required, but many functions can be carried out by modern modular wiring devices.

Some modular wiring examples:

The modular concept, such as that provided by ABB with its alpha bs series designs, allows most common products to be combined easily in a conventional two-gang box. Where special devices, such as an EIB unit, need to be installed, ABB provides simple adaptor plates. Full flexibility is provided by a dual box / front cover frame combination.

From Legrand Electric comes Mosaic TV Corner, product aimed at tidying up the clutter of cables that lie in the corner of virtually every living room. This multi-function panel is available in a 'pick and mix' format that allows buyers to specify the exact combination of functions they require. The compact design also ensures a neat, space-saving installation with no need to align individual accessories.

From Hager comes its Ashley system3.grid. Hager claims that it is the most comprehensive grid system on the market with a choice over 100 module variants and 56 front plates. In addition it is simple to fit and is future proofed. The frame accepts modules that are one, two, three or four modules wide so it can accept power, control, communication, detection and automation devices when they are available. Having installed a standard back box, system3.grid comprises three sections, mounting frame, 1 to 12 gang front plates in seven different surface finishes and the functional modules. The frames can also clip together allowing alignment of several frames for multi-gang applications. Installing the modules involves wiring them up before simply clipping them into the frame.

MK Electric's stylish and very slim Edge wiring accessories now include combination plates that provide sockets for power, digital and satellite TV, data and telephone in one outlet. The Edge combination plates are either rectangular or square, comprising two double switch sockets, back boxes and either a four module 100 x 50mm Euro sized aperture or an eight module 100 x 50mm Euro sized aperture respectively. The frontplates are available in a variety of finishes to suit individual choice. Installation is easy and the sockets and outlet are all precisely aligned, avoiding the possibility of an uneven or unsightly installation. The product's flexibility means that customers can order Euro TV / data / and phone modules to their own specification to fit into the Euro aperture and back boxes available separately for first fix. For 'smart home' applications,

Hager' s Tebis TS system is more than a modular wiring system and features a backbone comprising a single twisted pair cable so that any amount of control can be added without any further re-cabling. Control scenarios are also easily changed or extended without messy refurbishment work. The system commonly controls lighting, heating and motorised shutters or curtains, but can also interact with smoke and burglar alarms. Any control combination is potentially possible.

On the industrial side, and also from Legrand comes the P17 Tempra range of plugs and sockets. These provide easy maintenance, speedy installation and extra safety. The unit includes an inter-lock such that in lock position one, the switch cannot be turned on unless a plug has been inserted. In lock position two the plug cannot be removed when the switch is on. Segregation between the double and triple units enables different voltages to be kept completely separate. This flexibility enables installers to create their own special assemblies from a Legrand Mosaic socket outlet to a 63A socket, all accommodated in one unit using standard catalogue items. The double and triple units complement the single units, providing installation of up to 18 modules. The DIN rail option enables the full range of Legrand Lexic modular devices to be housed.