H&S Reference
Health and safety legislation has always placed an absolute or strict duty on employees to ensure that all parts of a workplace, both internally and externally, are adequately illuminated.  This has entailed the provision of both ambient or background lighting to maintain safe working areas and specific lighting at machinery and workstations where a higher level of lighting may be required because of the hazards arising from work activities.

The duty to provide and maintain light

The WHSWR impose and absolute duty on an employer to ensure that every workplace has both ‘suitable’ and ‘sufficient’ lighting.

  • Lighting shall, so far as is reasonably practicable, be by natural light.
  • Suitable and sufficient emergency lighting shall further be provided in any room in circumstances in which persons at work are specially exposed to danger in the event of failure to artificial lighting.
  • Lighting must be ‘suitable’ in terms of freedom from various forms of glare.  It must also be adequately distributed and maintained.  ‘Sufficient’ lighting, on the other hand, is considered to be he amount of light necessary to generally ensure safe working and to enable people to undertake specific tasks without suffering visual fatigue or eyestrain.
  • The ACOP on this mater must be read in conjunction with these general duties under the regulations.  HSE Guidance is also available on the subject.
  • These regulations further place an absolute duty on employees in terms of maintenance of lighting arrangements.  In this case, there is an absolute duty on the employer to ensure the workplace, equipment, systems and devices are maintained (including cleaned as appropriate) in an efficient state, in efficient working order and in good repair.  Moreover, where appropriate, devices and systems to which this regulation applies must be subject to a suitable system of maintenance.
  • The Provision and Use f Work Equipment Regulations 1998 also impose an absolute duty on employers to ensure that suitable and sufficient lighting, which takes account of the operations to be carried out, is provided at any place where a person uses work equipment.

All these requirements must be taken into account in any risk assessment process undertaken by the employer.

Assessing workplace lighting

Any assessment of lighting in the workplace should take account of the following aspects:

  • The adequacy of natural and artificial lighting, particularly where work equipment is in use;
  • Procedures for measuring levels of illumination;
  • The presence of glare in its various forms;
  • The efficiency of light distribution;
  • Lighting maintenance and cleaning arrangements; and
  • Emergency lighting arrangements.

HSC approved code of practice

The ACOP makes the following points about lighting in the workplace.

  • Lighting should be sufficient to enable people to work, use facilities and move from place to place safely and without experiencing eye-strain.  Stairs should be well-lit in such a way that shadows are not cast over the main part of the treads.  Where necessary, local lighting should be provided at individual workstations, and at places of particular risk such as pedestrian crossing points on vehicular traffic routes.  Outdoor traffic routes used by pedestrians should be adequately lit after dark.
  • Dazzling lights and annoying glare should be avoided.  Lights and light fittings should be of a type, and so positioned, that they do not cause a hazard (including electrical, fire, radiation or collision hazards).  Light switches should be positioned so that they may be found and used easily and without risk.
  • Lights should not be allowed to become obscured, for example by stacked goods, in such a way that the level of light becomes insufficient.  Lights should be replaced, repaired or cleaned, as necessary, before the level of lighting becomes insufficient.  Fittings or lights should be replaced immediately if they become dangerous, electrically or otherwise.
  • Windows and skylights should where possible be cleaned regularly and kept free from unnecessary obstructions to admit maximum daylight.  Where this would result in excessive heat or glare at a workstation, however, the workstation should be repositioned of the window or skylight should be shaded.
  • The normal precautions required by these and other regulations, for example on the prevention of falls and fencing of dangerous parts of machinery, mean that workers are not in most cases ‘specially exposed’ to risk if normal lighting fails.  Emergency lighting is not therefore essential in most cases.  Emergency lighting should, however, be provided in workrooms where sudden loss of light would present a serious risk, for example if process plant needs to be shut down under manual control or if a potentially hazardous process needs to be made safe, and this cannot be done safely without lighting.
  • Emergency lighting should be powered by a source independent from that of normal lighting.  It should provide sufficient light to enable persons at work to take any action necessary to ensure their, and others, health and safety.

The quantity of light

The current criteria for deciding what is sufficient lighting are the recommended average and minimum measured illuminance published in HSE Guidance Notes HS(G)38: Lighting at Work.

Light flow or ‘illuminance’ is the quantity of light emitted from a light source such as fluorescent strip or a bulb.  Lighting is measured quantitatively in Lux.  Average and minimum measure illuminances (in Lux) are based on both the general activity undertaken and the type of work location and/or work carried out.  No maximum illuminance level is specified.  See tables 5 & 6 below.

Table: Average illuminances and minimum measured illuminances for different types of work.

General activity Typical locations/types of work Average illuminance (Lux) Minimum measured illuminance (Lux)
Movement of people, machines & vehicles Lorry parks, corridors, circulation routes 20 5
Movement of people, machines and vehicles in hazardous areas, rough work not requiring any perception of detail (1) Construction site clearance excavation and soil work, docks, loading bays, bottling and canning plants 50 20
Work requiring limited perception of detail (2) Kitchens, factories, assembling large components, potteries 100 50
Work requiring perception of detail Office, sheet metal work, bookbinding 200 100
Work requiring perception of fine detail Drawing offices, factories assembling electronic components, textile production 500 200
 

Notes

  1. Only safety has been considered, because no perception of detail is needed and visual fatigue is unlikely.  However, where it is necessary to see detail, to recognise a hazard or where error in performing the task could put someone else at risk, for safety purposes as well as to avoid visual fatigue, the figure should be increased to that for work requiring the perception of detail.
  1. The purpose is to avoid visual fatigue, the illuminances will be adequate for safety purposes.
Table : Maximum ratios of illuminance for adjacent areas
Situations to which recommendation applies Typical location Maximum ration of illuminances
-working area
Maximum ration of illuminances
-adjacent area
Where each task is individually lit and the area around the task is lit to a lower illuminance Local lighting in an office 5 1
Where 2 working areas are adjacent, but one is lit to a lower illuminance than the other Localised lighting in a works store 5 1
Where 2 working areas are lit to different illuminances and are separated by a barrier but there is frequent movement between them A storage area inside a factory and loading bay outside 10 1

Lighting of the work area and adjacent areas is important.  Large differences between them may cause visual discomfort or even affect safety in places where there is frequent movement of traffic.  This problem arises most often where local or localised lighting in an interior exposes a person to a range of illuminances for a long time, or where there is movement between interior and exterior working areas exposing a person to sudden changes of illuminance.

To guard against danger and discomfort the recommendations in the Table should be followed.

Recommended lighting levels

The Chartered Institution of Building Services Engineers (CIBSE) recommend the following lighting levels (measurements in Lux):

Table : Recommended lighting levels

Commercial offices
General offices
Computer workstations
Conference rooms, executive offices
Computer and data preparation rooms
Filing room

500
300-500
500
500
300
Banks and building societies
Counter, office area
Public area

500
300
Hotels
Entrance halls
Reception, cashiers and porters' desks
Bars, coffee bars, dining rooms, grill rooms, restaurants, lounges
Cloakrooms, baggage, rooms
Bedrooms
Bathrooms

100
300
50-200
100
50-100
150
Retailing
Small retail outlets
Grocery/vegetable stores
Showrooms
Covered arcades and malls

500
500
1000
500-700
50-300


The quality of lighting

Average illuminance and minimum measured illuminance relate to the quantity of lighting for a particular task.  For lighting to be suitable, it is necessary to consider the qualitative aspects of lighting and the design of lighting.

The following aspects are significant in the design of lighting for work stations and installations.

Glare

This is the effect of light which causes impaired vision or discomfort, and is experienced when parts of the visual field are excessively bright compared with the general surroundings.  Glare, in its various forms, can be a contributory factor in accidents

Glare is experienced in three forms:

a)    Disability glare-the visually disabling effect caused by bright bare lamps directly in the line of sight;

b)   Discomfort glare- the visual discomfort caused mainly by too much contrast of brightness between an object and its background; and

c)    Reflected glare-where the reflection of bright light sources on wet or shiny work surfaces, such as plated metal or glass, can almost conceal the detail in or behind the surface which is glinting.

Distribution

The way in which light is distributed or spread is an important feature of lighting design.  The British Zone Method classifies luminaries (light fittings) according to the way in which they distribute light from BZ1 (all light down in a narrow column) to BZ10 (light in all directions).

This is particularly important where it may be necessary to illuminate danger areas and hazards arising from machinery.

Colour rendition

This refers to the appearance of an object under a given light source compared with its colour under a reference illuminant e.g. natural light.  Colour rendition enables correct perception of the colour.  Incorrect perception of colour by an individual can be a contributory factor in incidents involving, for instance, electricity supply e.g. incorrect wiring of a fitting.

Diffusion

This is the projection of light in many directions with no directional predominance.  Diffused lighting, in many cases, will reduce or soften the output from a particular source and so limit the amount of glare that may be encountered from bare fittings.  To be effective, diffusers must be cleaned on a regular basis.

Lighting maintenance

There is an absolute duty on employers to maintain the workplace, equipment, systems and devices ‘in an efficient state, in efficient working order and in good repair’.  This includes lighting systems and fittings.

A planned preventative maintenance programme, including the keeping of records of assessment and maintenance, is necessary to ensure compliance with this general duty.  On this basis, lighting maintenance should feature in an organisations planned preventative maintenance programme.  This should include regular cleaning and replacement of lamps, maintenance of systems and fittings, together with regular assessment of illuminance using a standard photometer (light meter) in order to ensure these illuminances are maintained.

Emergency lighting arrangements

Emergency lighting may be necessary in any part of a workplace where danger can arise from a failure of the lighting system.  In the event of the artificial lighting system failing, the emergency lighting arrangements should come into operation.  This takes two forms:

a)    Standby lighting – which enables essential work to continue; and

b)   Escape lighting – which enables a building to be evacuated safely.

Current fire safety legislation requires the lighting of escape routes.

Standby lighting

Much will depend upon the nature of the work undertaken and the risks arising form same.  It may be between 5% and 100% of the illuminance level currently provided.

Escape lighting

The general recommendation is that escape lighting should reach the necessary illuminance level within 5 seconds of the failure of the principal lighting system, although if the occupants are familiar with the layout of the premises this may be increased by 15 seconds.

Escape lighting may take the form of battery-powered installations designed to operate for between 1 and 3 hours according to the size of the premises and problems arising from evacuation.  Other systems powered by generators will operate for as long as the generator functions and should at least match the operating times of the battery-powered installations.

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