Lighting - Working in the light fantastic
March 1st 2004

While it is very easy to take lighting for granted when its working, paying more attention to the lighting in a factory, assembly area or warehouse can have a significant effect on productivity and overheads. Cliffe Tribe of Wirefield Lighting explains

As with most services in a

building, people rarely give

lighting a second thought until it goes wrong. Yet the quality of the lighting has a significant effect on many aspects of every business particularly the productivity and safety of staff and the overall cost of running the facility.

Because of its importance, the design of a lighting system has to address a wide range of issues, starting with what needs to be achieved and then which products will achieve the objective in the best way. In the

industrial sector there is rarely a need for anything fancy to look at, as there would be in a retail environment, but it is important that the fittings are reliable and provide long, trouble-free life. The lighting also needs to address the varying needs of each area, so it is usually necessary to use different types of light fitting in different areas.

For example, in an area with a high roof the light has a long way to travel from where the fittings are installed to where it is needed at the working level. This requires powerful light sources and luminaires that direct the light to where it is needed usually in the form of high bay luminaires.

In most cases, high bay luminaires will use high intensity discharge lamps such as high-pressure sodium, metal halide or mercury-blended fluorescent. High pressure sodium has long been the mainstay of high bay lighting as these light sources offer proven energy efficiency, reliability and longevity and meet the needs of most applications.

For areas where better colour rendering is required, a decision may be taken to use metal halide, as it provides a higher colour-rendering index but there can be issues with lamp life and general reliability. So it will really depend on what you need and which lamp is right for your application your lighting supplier will usually be able to provide advice on this issue.

Maintenance is a particularly important consideration for high bay fittings because of the difficulty of access. Special access towers will often be required and any re-lamping and cleaning work will generally be performed out of hours. Inevitably, this leads to disruption and higher costs for maintenance staff or sub-contractors as well as all of the associated health and safety paperwork.

All of which reinforces the need for reliability and long life and there are strong arguments for choosing luminaires that incorporate a self-cleaning feature using natural convection currents, as well as digitally timed ignitors to prevent the harmful effects of lamp cycling.

It is also vital to get the light distribution right, so that the light goes to where it is needed and none of it is wasted. While much of this light will be directed towards work or picking areas, there is a benefit to directing some of it to light coloured walls, so the light is reflected back into the space. This creates an airier, more spacious feel and a more pleasant working environment, all of which makes a positive contribution to staff morale and productivity.

The same principles apply to all areas of the facility. Where ceilings are lower, on mezzanine floors perhaps, high bay fittings will not be appropriate but low bay or mini high bay fittings can provide the same benefits. Or for even lower ceilings, such as in offices, robust fluorescent fittings may be a more suitable choice.

Outdoor areas like loading bays require special consideration because, as well as providing effective, glare free lighting, it is also necessary to minimise light pollution from these fittings. Again, precise photometrics that direct the

light to where it is needed will ensure that drivers are not blinded by glare

and no surplus light is projected into the sky.

While a combination of standard high bay, low bay and fluorescent fittings will meet most needs; there are times when something special is required. In low or high temperatures, for instance, it may be necessary to use special fittings that are designed to operate at extreme temperatures. Similarly, where there is a lot of dust there is an explosion hazard if the dust penetrates into the light fitting

and is ignited by a spark. This danger

can be avoided by the use of fittings specially designed for hazardous

areas.

In many factories and warehouses in the past, there has been a tendency to sacrifice the quality of the lighting in some areas for the convenience of using a limited range of luminaire types. A

better solution is to source the lighting from a supplier that can meet all of the varying needs, as well as meeting the criteria for efficiency, performance and reliability.