Under the Health & Safety at Work Act 1974 an employer has a duty to ensure the health & safety of employees. The Act includes a duty to provide lighting to ensure that work can be done safely and that employees health or eyesight are not jeopardised.

The provisions contained in the Management of Safety at Work regulations, especially regulation 3 'risk assessment', are also relevant.

Regulation No.8 of the Workplace Regualtions 1992 states that employers must ensure that:

• Every workplace has suitable & sufficient lighting
  
• This should be natural light, so far as is reasonably practicable
  
• Suitable & sufficient emergency lighting shall be provided where needed
  

Guide to required light levels

The amount of light required depends on the type of work being done, but the lisr below gives an indication of the amount of light required for the different kinds of work:

Movement of people (storage area and plant room)       150-250 Lux

No perception of detail (construction, loading bays)        300-500 Lux

Limited perception of detail (factories, kitchens)              500-750 Lux

Demanding work (inspection, welding, machinery)          750-1000 Lux

Repetitive work (electronics, textile production)              1000-1500 Lux

Accurate detail (technical offices)                                     1500-3000 Lux

Precision detail (jewellers and goldsmiths)                      3000+ Lux

Typical Outdoor Light Levels

Interior levels are much lower than outdoor natural light. Some typical light levels are:

Very bright summer day                  100,000 Lux

Full daylight                                    10,000 Lux

Overcast summer day                    1,000 Lux

Very Dark Day                                100 Lux

Twilight                                           10 Lux

Deep Twilight                                 1 Lux

Full Moon                                      <1 Lux

Light Measurements

Light can be measured in many ways. Lux and Footcandles are the two most popular measurements chosen by industry. The ‘lux’ range is a European standard, and ‘Footcandles’ are a US scale.

Lux (Lux) is a unit of illumination of one square metre, which is one metre away from a uniform light source.

Footcandle (FC) is a unit of illumination of one square foot, which is one foot away from a uniform light source.

1 Lux + 0.0929FC               1 FC = 10.76 Lux