But are they fair? Not at all, according to BSRIA scientist Mark Roper and his team of specialists who have just compiled the comprehensive Fibre optic lighting guide (AG 14/2000), the first such document to surface in this country.
The Guide is, above all, objective. It doesn't try to sell anything to anyone. It simply helps users answer the questions: "Is this technology appropriate for me?" and "What else do I need to know?".
Roper believes that electrical installers can play a crucial role in elevating the reputation of this highly efficient, easily maintained and very safe technology.
The system itself sounds far more complex than it actually is. It typically consists of three major components: the light source, which contains the lamp, controlgear and filters; the fibres, usually bundles of fibres formed into a harness with individual tails to each lighting point; and the end fittings, which secure and protect the end of each fibre tail and control the emission of light.
Installers must ensure that the harness lengths are right, as adding more fibre is impossible. It's also important to remember that the fibres are breakable and extremely difficult to repair. If the fibres are bent out of shape they won't transmit any light, so they should not be walked on or drawn tight over sharp edges, which could damage the outer cover and fracture the fibres within.
Also, wherever the light source is located, it must be adequately ventilated to ensure full lamp life and prevent overheating of the optical components and fibre terminals.
Despite these cautionary words, Roper insists that installing fibre optics is not as complex as normal electrical cable, and contractors are quite capable of performing the installation alongside other duties. It's worth remembering that manufacturers are now producing guides to fibre installation as well as running short training courses.
Intact harnesses present a minimal risk to installers, says the Guide. However, broken or damaged harnesses with exposed fibres do present the risk of fibre fragments. These can pierce the skin and eyes, so good housekeeping practices should be adopted to minimise the risk, and installation staff should be trained in safety procedures.
The overall route of the harness should be decided at the design stage, leaving the detail to the installer. Harness can be laid along existing cable tray and trunking, but in most cases it will be laid along the shortest route from light source to end fitting, often over false ceilings.
Roper claims that most end fittings are simple to install, in a similar manner to conventional fittings, although in some cases more room may be needed to allow the fibre to enter.
As with the light sources, end fittings may be installed before other services are finalised. Soiling by brick or plaster can reduce the light output from the emitter though, so ideally, the fibre optic system will be one of the last services installed.
Roper points out that fibre technology is not new, even though it remains unfamiliar to large sections of the building services industry. And he claims that the purpose of the new Guide is to "help the industry find out for itself", not thrust the technology in its face.
Fibre optics have been widely used in such highly specialised applications as art galleries and museums. This is because, unlike conventional lighting, they do not emit heat and, very important with delicate paintings and tapestries, there are no ultraviolet or infrared emissions.
But Roper insists fibre optic lighting also has considerable advantages in conventional buildings. Energy use, for instance, by a fibre optic system should be less than the competing technologies.
While the fibre system has additional insertion and attenuation losses, these are offset by the use of a single large lamp, with a greater efficiency than the smaller lamps used in other systems.
The Guide adds that fibre optics may allow a reduction in energy use in other areas. Conventional lighting systems may contribute a significant heat load to the occupied space, adding to any cooling requirement. If the light source can be placed outside the space, then a reduction in the cooling load may be achieved.
There are also potential savings to be made in maintenance – the greatest obtained where the end fittings are located in an inaccessible location. The Guide opines: "In such cases, expensive and disruptive access equipment would be required to service and maintain a conventional system." For a fibre optic system, any servicing should only be required at the light source, which should be located for convenient access. End fittings may require occasional cleaning depending on the environment.
Despite the benefits of fibre optics, there's no getting away from the fact that capital costs will be substantially higher than the components of a conventional system. This is mostly because fibre optic lighting systems are not currently high volume products and the harnesses are usually unique items for each application.
But Roper says there is a move by manufacturers towards producing standard multi-functional systems, which will reduce the costs. Even so, the hardware cost for a fibre optic lighting system is still likely to be significantly higher than most of the alternatives.
Roper believes that while the cost factor has held fibre optics back, many specifiers are too concerned with initial cost. With the savings on energy to be made, using fibre optics can be a much better option than conventional systems. And reduced installation times mean significant cost savings. That's why, says Roper, the UK is at last waking up to fibre optic lighting.
Source
Electrical and Mechanical Contractor
