Lighting – just a matter of common sense? Part Two
In this article split over three parts, Dr Richard Brown looks at effective lighting at work and how it enables safe working. This second part discusses minimum lighting levels and temporary lighting strategies. You can catch up on part one here.
It is perhaps a matter of ‘common sense’ that effective lighting at work is required and enables safe working. However, common sense very often isn’t common, and this article sets out the legal requirements, good practice, associated hazards and some tips on lighting strategies. Dr Richard Brown, Head of Expert Services at Finch Consulting, muses over his experience with lighting over his well-established career.
The legal requirements are detailed in part three of this article and referred to throughout the body of it. The article does not discuss lighting requirements in explosive or potentially explosive atmospheres.
Minimum lighting levels
WHAT IS LUX?
Lux is the unit of measurement for illuminance. The difference between lumens and lux can often cause confusion. It can be most easily explained by thinking of luminance as the amount of light emitted from a light source whereas illuminance is the amount of light at a particular point away from the light source. 1 lux means 1 lumen per square metre.
Lighting at Work Guidance HSG38 provides guidance on minimum lighting levels for everyday use inside and outside of buildings and covers the illuminance on the task and illuminance ratios.
Illuminance on the task
The amount of lighting required depends on the amount of detail that a person needs to see and can also depend on the age of the worker and the speed and accuracy by which the task needs to be undertaken. Lighting is measured in the unit, Lux.
Examples of lighting requirements in different work environments and situations
Further details on specific lux levels in different work environments are detailed in the CIBSE “Code of Lighting” A summary of these specific lighting levels for different work environments has been summarised by Kellwood Lighting, see link below. These could be used to highlight the differences in different work environments.
This is explained in HSG 38 on page 30, ‘The relationship between the lighting of the work area and adjacent areas is important. Large differences in illuminance between them may cause visual discomfort or even affect safety in places where there is frequent movement. This problem arises most often where local or localised lighting indoors exposes an employee to a range of illuminances for a long time, or where the movement between interior and exterior working areas exposes an employee to a sudden change of illuminance. To guard against danger and discomfort, the recommendations in the table below need to be followed”
Temporary lighting strategies
This article has not concentrated on fixed lighting requirements, but the design of these can be aided by legislation and design specialists. I have provided a few anecdotes from the industry to provide some content on lighting issues and some solutions that I have found to be useful.
For any queries related to what you have read here please email [email protected].
Look out for part three coming soon.
 This is provided at a cost of £150 by the CIBSE