Electrical lighting has been a pivotal feature of everyday life for more than 100 years. Our modern lifestyle is not viable without artificial lighting. But how do we ensure it does not introduce hazards in industrial areas such as construction sites and confined spaces?
Lighting is used for many different purposes: to ensure visual work can be done accurately, safely and in comfort; to increase timely production, and to enhance security and to promote the health and wellbeing of workers; to make the workplace an attractive and pleasant environment.
Appropriate lighting and lighting controls, including the provision of emergency lighting, are crucial to enable the workforce to perform its activities and to move around safely. Inadequate lighting can make it difficult to see clearly and may contribute to hazards such as slips, trips and falls, while excessive lighting can cause discomfort and may mask otherwise obvious hazards through dazzling workers. The primary purpose of adequate lighting is to ensure that visual tasks are carried out quickly, safely and accurately. Providing appropriate and sufficient light levels and contrasts in the workplace not only helps to reduce negative health symptoms, but also aids in perception of potential hazards. Improvements in lighting conditions can result in as much as 10% productivity gains and 30% reduction of errors.
Lighting at construction sites
Adequate lighting on construction sites is vital for the workers’ safety, productivity and the quality of the work. Construction sites challenge contractors to provide adequate lighting because of the changing nature of the build process. Unlike finished buildings, evacuation routes on construction sites often contain construction materials, portable equipment and other obstacles. The client, through their principle contractor, should make electrical contractors aware of the project’s lighting requirements during the construction tendering process. These requirements should take into account various phases of the construction project where lighting may need to be relocated. The impact of the lighting on the surrounding environment should also be taken into account. Light pollution can not only have an adverse effect on wildlife, but can also be a nuisance to local residents, especially at night.
Employers need to ensure that any artificial lighting provided does not change the apparent colour or visibility of any safety signs or other safety related items such as fire extinguishers. Temporary lighting should be equipped with heavy-duty electric cords with connections and insulation maintained in safe condition. Temporary lights may not be suspended by their electric cords unless cords and lights are designed for this means of suspension. Splices shall have insulation equal to that of a cable.
Lighting in confined space
Adequate and suitable lighting is essential for entry and work in a confined space. Confined spaces generally have poor natural lighting available, requiring artificial lighting. Portable lighting and personal work lights used in confined space require special consideration due to the nature of hazards and must meet the required industry standards to avoid potential risks. Non-sparking tools and specially protected lighting are essential where flammable or potentially explosive atmospheres are likely. There are different standards used for hazardous areas and electrical equipment designed for use in those environments, depending upon where in the world they are to be used.
Access and passage into a confined space should be provided with illumination of not less than 50 lux. All portable hand-held lighting provided in confined spaces should be operated at a voltage not exceeding 55 volts (AC) between the conductor and earth or 110 volts (DC).
Lighting and health
Both natural and artificial (local) lighting influence our health and wellbeing. It directly affects our mood and alertness. The effect of lighting on vision is the most obvious impact on the workforce. Depending on how the illuminance is delivered, the result can either be comfortable or uncomfortable. Visual problems and discomfort occur when the lighting makes it difficult for workers to see what they are supposed to see while performing their jobs, which in turn can affect their performance negatively. Aspects of lighting that can commonly cause visual discomfort are insufficient or excessive lighting, shadows, veiling reflections, glare and flicker.
“working in inadequate light levels triggers the release of the sleep hormone melatonin, which in turn reduces alertness and increases the chances of errors and accidents”
Poor lighting, particularly lighting that causes glare, can present visual discomfort which may result in headaches, sore eyes, and aches and pains associated with poor body posture. The likely consequences of prolonged exposure to uncomfortable lighting conditions include eyestrain and related problems. The symptoms of eyestrain vary from one worker to another, but burning or itchy eyes, headache, blurred vision, dry or watery eyes and tensed muscles are very common. In addition to this, poor lighting also affects the endocrine system. Working in ‘darker’ workplaces triggers the release of the sleep hormone melatonin, which in turn reduces alertness, and increases the chances of error and accident risks. This further leads to lower productivity and poor quality work. In order to tackle such issues there must be ‘suitable and sufficient’ lighting. Natural (day) light should be utilised so far as is reasonably practicable. Natural light is often found to positively influence human health and wellbeing (Boyce et al, 2003). Several research studies have demonstrated that natural light has tremendous physiological and psychological benefits.
Implications of inadequate lighting
Poor lighting can affect the quality of work, specifically in situations where precision is required, and overall productivity. Inadequate lighting not only affects the health of workers, causing symptoms like eyestrain, migraine and headaches, but is also linked with a condition called ‘Sick Building Syndrome’. Symptoms of this condition include headaches, lethargy, irritability and poor concentration. In addition, inadequate lighting within workplaces can also contribute to a significant cost to the business in the form of:
- Product damage due to an accident
- Production lost time as a result of accidents
- Time off work due to personal injuries
- Reduced workers’ efficiency
In order to maintain a productive, safe and healthy workplace, the following lighting conditions should be avoided:
- Inappropriate and insufficient light at the point of work activity
- Uneven or flickering lighting within the workplace
- Veiling reflections and shadows on the task
- Natural light openings too bright and bright reflected images adjacent to the task
- Excessive range of brightness and stroboscopic effects
Natural and artificial lighting
Most people prefer to work in natural daylight; therefore, it is essential to make full use of it. There are many studies concerning natural daylight and its positive effects on human physical and mental health such as stress and mood. However, natural light by itself does not usually provide sufficient illuminance throughout the whole working area or for the entire working day; in most circumstances sufficient and suitable lighting can be provided by a combination of natural and artificial (local) lighting. However, due to their architectural design, some workplaces lack the benefits of available natural light and, in these cases, suitable local lighting needs to be introduced so that tasks can be performed safely and efficiently.
The precise levels of natural and/or artificial lighting required will depend on the activities taking place, as different tasks require different levels of illuminance. Various international lighting standards and codes use ‘illuminance’ as the main quantitative criterion for lighting provision in the workplace and contain ranges of recommendations for maintained illuminance in various indoor and outdoor areas depending on activity and area types. Workers with visual impairment may require more light in order to perform a task than their colleagues. Furthermore, a 70-year-old worker may need three times as much illuminance than the level of illuminance required by a 20-year-old (Weale, 1983).
The amount of light required within a workplace depends on the task being undertaken. The fabric and design of a building also influence the level of local lighting requirements. The amount of light falling on a surface is measured in units called lux. Typical illuminance levels within workplaces are usually between 500 and 1,000 lux when measured 76 cm (30 inches) above the floor.
Depending on how much detail needs to be perceived, lighting standards and codes provide detailed lighting recommendations for a variety of tasks or activities. The table below provides some recommended average illuminances for different work settings.
The recommended illuminances for different work settings can be obtained from industry codes of practices such as BS EN 12464-1 (2011) and SLL Code for lighting (2012). Depending on how much detail needs to be perceived, lighting standards and codes provide detailed lighting recommendations for a variety of tasks or activities.
Lighting and performance
Poor lighting is a safety hazard - misjudgement of the position, shape or speed of an object can lead to accidents and injury. The extent to which various lighting levels affect workers’ performance depends on the proportion of the visual component within the visual task.
“poor lighting is a safety hazard - misjudgement of the position, shape or speed of an object can lead to accidents and injury”
Interior design and colour rendering
Limitations imposed by the layout and design of the workplace may result in the employer choosing a particular lighting scheme. For example, a large warehouse with no windows will have different lighting requirements to small open-plan office with several large windows. Large and bulky storage shelves and machinery in the warehouse may cause excessive differences in the illuminance between areas. Lighting schemes need to consider such factors especially in areas where illuminance may be inadequate to perform a task safely.
Although various light patterns and shadows have the tendency to make workplaces more ‘sparkling’, animated and dynamic, colour rendering also plays an essential role, as it defines the ability of a light source to render object colours precisely. Good and appropriate colour rendering helps to reduce incidents as it allows workers to see coloured objects more clearly. Research has demonstrated that around 4% - 5% of the working population has defects in its colour vision with the most common type being red/green colour blindness. Some people may say that the term colour blind is misleading, as such colour vision deficiencies vary from practically normal levels of colour sensitivity to very severe loss (Rodriguez-Carmona et al, 2012). Increasing lighting levels may be the most obvious solution in this matter; however, increasing the contrast between the tasks and their backgrounds, and improving the reflectance of walls and ceilings etc. can further improve the visibility.
Having adequate lighting with very appropriate colour rendering is vitally crucial for workers with colour vision deficiencies, as it can help them to differentiate between colours that would not be visible at poor light levels or under a different light spectrum (Jennings and Barbur, 2010).
For example, in dark environments, our ability to distinguish between different colours is impaired. At low light levels, receptors in our eyes called rods that provide peripheral vision and movement detection become dominant over cones, which are sensitive to colour, detail and contrast in the central field of view, and operate in well-lit environments. Ensuring adequate illumination to stimulate the cones is therefore important for tasks requiring colour discrimination.
Emergency lighting is of paramount importance in workplaces as it enables safe evacuation or safe continuation of essential processes. When normal lighting fails, emergency lighting must be triggered for as long as potential hazards exist, or until normal lighting is resumed. Emergency lighting can take several different forms depending on its purpose and must be provided from a source independent of that supplying the normal workplace lighting.
Several requirements apply to emergency lighting. For example, BS EN 1838:2013 recommends a minimum horizontal illuminance of 1 lux at floor level, along the centre line of an escape path, while 0.5 lux on the empty floor in open spaces, with a minimum CRI of 40 to make possible identification of safety colours. For high risk working areas, the minimum maintained illuminance on the working plane needs to be 10 percent of the required task illuminance, but at least 15 lux.
Lighting and vehicle movements
Inadequate lighting is one of the major causes of accidents involving moving vehicles. In poor lighting conditions risk increases for vehicular collisions and pedestrian trips and falls. There should be adequate lighting of site locations at all times to enable all workers to work safely. For transport safety, all roads, manoeuvring areas and vehicle yards must be sufficiently lit. Adequate lighting should be provided to all areas where vehicle movements take place, especially to those areas used in darker hours. Particular attention should be paid in areas where loading/unloading takes place. As a minimum, lighting should be provided for junctions, around plant, buildings and pedestrian routes. Measures should also be placed in order to avoid a strong change in the amount of light between the inside and outside of buildings. Steep differences in light levels between work areas increases risks of accidents. Moving from a bright to a dark environment can result in temporary blindness lasting up to 30 minutes as the visual system adapts. Workers operating close to vehicle access routes in transitional environments should wear high-visibility clothing.
Another important factor is the presence of clearly visible hazard warning signage. All signs must be illuminated for night-time visibility and in adverse weather conditions. All vehicles on site make use of lights/beacons in poor visibility conditions to aid detection by other vehicles. Further guidance for road lighting can be found in BS 5489 ‘Road Lighting’.
Design and installation considerations
It is vitally important that businesses consider the working conditions in which lighting is used. Activities that create flammable, dusty and explosive atmospheres may necessitate the need for lighting design that protects against dust ingress and which does not ignite. Care should be taken to keep flammable materials away from lights that operate at high temperatures.
The type and strength of lighting in workplaces depends on:
- Its suitability for use
- The area it intends to cover
- The design and layout of the area
- The purpose for which it will be used
Lighting can increase productivity, especially when worker controlled lighting is provided. A research study reported a 4.5% increase in productivity by enabling individual control over lighting (Juslén et al 2007).
“improvements in lighting conditions can result in as much as 10% productivity gains and 30% reduction of errors”
Lighting control systems
A lighting control system is a mechanism of lighting controls that allows employers to have control of the lights in their workplaces. It can be anything from a simple mechanical switch to a complicated automatic control system capable of responding to the amount of light present. The benefit of a lighting control system over stand-alone lighting controls is the ability to control individual lights or groups of lights from a single user interface device. Employers need to make sure that they do not place manually operated switches in a position where workers have to reach past machinery or cross a dark area to operate them. Lighting installations with lighting control systems should set up a ‘fail safe’ feature so that if the control system fails, work areas will not be plunged into darkness. It is also advisable to have a manual override system on top of automatic control systems which can be used if the automatic system fails.
Maintenance of lighting
It is very important to keep the installed lighting systems in effective working order. The output of light decreases with the age of the light source. The common reasons for the decreased outputs are:
- General wear of the light sources
- Accumulation of dirt on fixture
- Dirty reflectors
- Dusty anti-glare devices
Dirt on light fixtures is the major factor for loss of lighting. Like everything else, lighting devices also grow old over time. After a period of time, they start emitting less light. It is therefore important that they should be replaced rather than waiting until they burn out. Ordinary light bulbs usually have the shortest lifespan and provide the least light. They normally last about 1,000 hours compared to modern fluorescent tubes which last over 10,000 hours.
The type of work activity within a workplace determines how quickly the light fixture becomes dirty. The required standard of lighting is more easily maintained if the light fixtures are cleaned and changed regularly. By regularly cleaning windows and skylights businesses can reduce the need for artificial light and ultimately, the costs of lighting. Cleaning the fixtures that enclose lamps, known as luminaires, will improve their performance.
It is vital to provide good quality lighting within workplaces that is designed to match the tasks being undertaken. The right levels and the quality of light have been shown to affect alertness and accuracy at work. The most important objective with lighting of a workplace is to satisfy the needs of the workers by offering them a comfortable and productive work space. By getting the lighting right, workers will be more comfortable in their working environment and they can become more productive with a reduced number of accidents.