Light is necessary to enable people to see and for this purpose sufficient and suitable illumination is require in workplaces. Good lighting is essential to prevent accidents and to ensure a safe and productive work environment. However, light consumes energy and money and should, therefore, be economically justifiable.
You may ask: “What is good lighting?”. Good lighting conforms to both quantity and quality standards.
Quantity
The desirable quantity of light, or the illumination level, depends primarily on the nature of the task. Factors such as the degree of accuracy, amount of detail and the colour of objects will determine the illumination level required.
Specific lighting levels are required or various work areas and tasks, as provided for in Environmental Regulation 3 of the OHSAct. Walkways for instance, should have an illumination level of 75 lux, cold rooms a level of 100 lux, whilst for watchmaking a level of up to 3000 lux is required.
Although the Lighting Regulation prescribe standards for a large number of workplaces, it can never be all inclusive. It is thus often left to the lighting designer or occupational hygienist to determine suitable standards for particular situations.
The said regulation is also not without controversy. For example, a minimum illumination level of 500 lux is required for offices where computers are operated. However, practical experience showed that such a high level causes troublesome reflections on computer screens and employees then tend to switch the lights of.
Quality
Quality of illumination refers to the distribution of brightness in the visual environment. For this purpose, the Lighting Regulation has a number of requirements (refer to Environmental Regulation 3(3)(a) – (d)), which are discussed below.
Uniform Illumination
In order to provide optimum visual conditions, all the objects and major surfaces in our visual field should be equally bright. The use of floodlights and High Intensity Discharge Lamps in the wrong applications often result in areas that are brightly illuminated, followed by deep shadows and areas of total darkness.
To achieve the goal of uniform illumination, it is always better to use more low powered lamps than a few high powered ones.
Glare
A second statutory requirement with regard to quality of illumination states that “glare in any workplace should be reduced to a level that does not impair vision”.
Glare may be defined as any brightness within the field of vision where such a characteristic would cause discomfort, annoyance, interference with vision and/or eye fatigue.
Glare can be direct (from an unshaded lamp) or indirect reflections (from a shiny surface).
No source of light should appear in the visual field of any worker and all light sources should be shaded. The use of reflective colours and shiny materials on machines, desks and other work surfaces should be avoided.
Flickering
Flickering is due to the alternating current of electricity and is mainly observed in fluorescent lamps. Flickering leaves the eye either over-, or under exposed as the pupil cannot cope with the rate of fluctuating brightness in the visual field. It has been shown that if two brightness levels fluctuate rhythmically, visual performance may be reduced as much as if the illumination level had been reduced from 1000 lux to 30 lux.
Flickering may also cause stroboscopic effects, in other words, it may create the illusion that moving machinery are standing still. The Lighting Regulation requires that “lighting on rotating machinery is such that the hazard of stroboscopic effects is eliminated”.
The avoidance of flickering can be achieved by using two or more fluorescent lamps, each served from different electrical phases. Rooms where people work should never be illuminated by a single fluorescent tube, but always with two or more lamps that flicker out of phase with each other.
Stroboscopic effects are avoided by covering moving machine parts and by providing an incandescent lamp above rotating machinery such as lathes.
Maintenance
Lighting systems in buildings are usually correctly designed to provide adequate illumination levels for the task at hand. However, with time illumination may fall below the required level. The main reason for this is lack of maintenance.
It is therefore not surprising that the legislator requires that “luminaires and lamps are kept clean and, when defective, are replaced or repaired forthwith”.
The following guidelines are provided to prevent the deterioration of illumination levels.
- Replace broken lamps on a regular (daily) basis. A planned relamping programme may also be considered.
- Lamps and shades should be cleaned regularly.
- Windows and translucent panels should be kept clean.
- Never obstruct windows with cupboards or by stacking material in front of them.
Conclusion
In the interest of safety and productivity the employer is required to provide illumination of a specified quantity and quality in al workplaces. It is, therefore, of little use to provide two or three floodlamps in a Warehouse in an attempt to achieve the desired quantity, but in the process deep shadows and glare are caused.
Lighting systems should be the result of proper planning, taking into consideration the visual demands o the task, statutory requirements and the availability of natural and artificial light sources.
AirCHECK conducts lighting surveys to ensure that your business
complies with statutory requirements and that the available light is used
economically and to its best advantage.
We do not only measure the amount of light, but offer a holistic
approach, which includes a full evaluation of the distribution of light, glare,
flickering, stroboscopic effects, as well as the maintenance of lamps.
AirCHECK can provide you with the following lighting surveys:
- Artificial (night-time)
lighting surveys.
- Day time lighting
surveys.
- Emergency lighting
surveys.
Comments
Post a Comment