Lighting Matters
Lighting Matters
Lighting falls into two main types: Hand held for manual, close work and scene lighting for larger areas. Our annual lighting feature has been divided into these two areas and explains what you need for different applications and considerations when purchasing this sort of equipment.
'Ex' Lighting in Confined Spaces
To follow are some factors to consider when selecting lighting equipment for use in potentially explosive gas, vapour, mist or dust atmospheres.
Confined spaces - a definition
A confined space is an enclosed or partially enclosed space where there is a risk of death or serious injury due to:
- Fire or explosion
- Toxic gas, fumes or lack of oxygen
- Drowning in liquid/being buried under a free flowing solid (e.g. flour)
- High temperature Confined spaces can occur in many places including:
- Process vessels, blend tanks and vats
- Cargo, ballast and void spaces on ships
- Support columns/legs/pontoons of fixed or mobile offshore structures
- Pits, culverts, pipes, drains, sewers, sewage pits, tunnels, trenches, ducts and shafts Due to the nature of confined spaces, the presence of permanently installed lighting is unlikely. When such areas must be accessed, for inspection, cleaning or maintenance activities, portable or temporary lighting must be used.
Confined spaces and lighting - selection criteria
The UK Health and Safety Executive's guide "Safe work in confined spaces" INDG258, advises that, with regard to the Confined Spaces Regulations 1997, "specially protected lighting [is] essential where flammable or potentially explosive atmospheres are likely." A wide variety of "Ex" explosion-protected lighting is available, designed for use in potentially explosive atmospheres. However, to ensure safe use, the correct selection criteria is critical. Factors to consider should include:
- Characteristics of explosive atmosphere (temperature class, gas group, zone)
- Amount and type of light required for task
- Task duration
- Conditions (e.g. wet, harsh)
Legislation - equipment for use in explosive atmospheres
The ATEX Directives now place a legal obligation on the employer to ensure appropriate electrical or mechanical equipment is used where a potentially explosive gas, vapour, mist or dust may be present.
The 94/9/EC (ATEX Equipment) Directive deals with "equipment and protective systems intended for use in potentially explosive atmospheres." Only "Ex" equipment which is CE marked compliant with this ATEX Directive (and any other relevant mandatory directive) may now be sold for use within the EU.
The 99/92/EC (ATEX Workplace) Directive covers the "minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres". The Directive lists a set of obligations for employers, requiring the adoption of a coherent risk assessment based strategy for the prevention of explosions and fire. Compliance with this Directive must be achieved by July 2006 for workplaces in operation before 30 June 2003. All new workplaces must comply from the date of commissioning.
The UK Government has implemented the 99/92/EC Directive as the Dangerous Substances and Explosive Atmosphere Regulations 2002 (DSEAR). These regulations also include the fire safety aspects of the 98/24/EC Chemical Agents Directive (CAD).
ATEX and DSEAR stipulate that all equipment for use in explosive atmospheres must be risk assessed, but that "equipment already in use before July 2003 can continue to be used indefinitely, provided a risk assessment shows it is safe to do so". The Health and Safety Executive advise that a risk assessment of equipment should include:
- Confirmation that non-ATEX "Ex" equipment has an approval for use in explosive atmospheres (e.g. Certificate of Assurance or Certificate of Conformity) and consideration of changes to the standards since the equipment was approved; have there been significant changes that would lead to the safety of the equipment being questioned?
- Verification that the equipment is appropriate for use in the explosive atmospheres expected to be encountered. The equipment's approval code (incorporating temperature class, gas group, and indication of compatable hazardous area zones) should be compared with the properties of the hazardous materials anticipated to be met (temperature class and gas group) and the likelihood that the material will be present (hazardous area zone). Environmental conditions the equipment will encounter should also be considered (resistance to water, dust, chemical attack, etc.).
- Confirmation that equipment is operated and maintained with due regard to safety.
Regulations and recommendations - lighting and lighting levels
The UK Health and Safety Executive publication "Lighting at Work" HSG38 refers to the Workplace (Health, Safety and Welfare) Regulations 1992: Regulation 8 which specifies that "every workplace should have suitable and sufficient lighting".
HSG38 also sets out minimum lighting recommendations. As an example, for "movement of people, machines and vehicles in hazardous areas or for rough work not requiring any perception of detail" average illuminance required is 50 lux, but with a minimum illuminance of 20 lux. If the activity is simply the "movement of people", average illuminance can reduce down to 20 lux. However, as tasks become more demanding, greater levels of illuminance are recommended, up to an average of 500 lux for "work requiring perception of fine detail", for example the assembly or installation of electronic components.
Whilst there is no direct reference to working in confined spaces, HSG38 acknowledges that outside work places "tend to have temporary lighting installations and portable lighting" and that the "lighting objectives for temporary installations should be the same as for permanent ones." That being said, it must be accepted that achieving these light levels in confined spaces with temporary lighting may well be difficult but, wherever workers have fully portable lighting available to them, they should achieve the light levels recommended, albeit over a localised area.
Confined spaces and lighting - equipment available
As previously stated, lighting in confined spaces will generally be portable or temporary. Different tasks in confined spaces or dark areas will require different types of lighting. Below is a list of product types and examples of where they may be appropriately used.
Safety torches - the most commonly found and generally lowest cost form of portable "Ex" lighting. Frequently found as a personal issue light source for simple maintenance and inspection. Generally primary cell powered, using C cells, or more cost effective D size cells. A recent advance is approval for alkaline cells, allowing the use of higher power light sources and giving longer duration before battery change. Straight torches are more commonly found in continental Europe, but right-angle torches are more prevalent in the UK for 'hands free" applications. Recent products to the market have new features such as higher efficiency halogen bulbs and low power indicators, warning the user when to change cells.
Handlamps - generally "Ex" handlamps are more powerful than a safety torch. They are commonly found as a rechargeable product, but are also available in primary cell form. Again, usage is centred on inspection and light maintenance work.
Mini Torch - now more commonly used because of their greater availability and convenient small size, they are ideal for use in very localised inspection work. Many use a filament bulb as a light source but more are now starting to use LED light sources.
Head Torch - ideal for true hands free use, useful for maintenance, but can have limitations. The original "Ex" head torches were developed from miner's cap lamps. Newer products benefit from being smaller and lighter in weight without a belt mounted battery pack, but often lack the light output and long duration of their predecessors.
Worklights - offer a greater level of light output than portable equipment but are generally bulkier and require a separate power supply. Worklights are generally used in temporary lighting installations, and are ideal for involved maintenance activities, such as cleaning, shotblasting and re-coating of tanks, or for general illumination to and from the site of maintenance work.
Battery powered "Ex" worklights are available with limited choice. Whilst having the benefit of being completely selfcontained for remote use with no trip hazards from trailing cables or hoses, a disadvantage can be increased weight because of the integral battery and the need to remove the lamp for charging. Light output can be much higher than that from torches and handlamps, but is still limited compared to other types of 'powered' worklight.
Mains powered "Ex" lead lamps are available in many different forms, from conventional incandescent 60watt handlamps to higher power halogen lamps, giving more directional light outputs, ideal for illuminating specific work areas. Alternatively, fluorescent units of varying sizes are available, with the advantage of a far greater efficiency than filament lamps, but a far more diffused light output. Equipment can vary in supply voltage, from 12 volts or 24 volts, sometimes running off an "Ex" transformer, up to 110 or 230 volts. The UK Health and Safety Executive advise that "in certain confined spaces (e.g. inside metal tanks) suitable precautions to prevent electric shock include use of extra low voltage equipment (typically less than 25V) and, where necessary, residual current devices", fusing or protection devices should be considered to minimise danger if cables are damaged.
Compressed air powered lamps are a further form of worklight for use in explosive atmospheres. Whilst having a lesser efficiency than lamps powered by electric cables, compressed air lamps have many advantages. The compressed air power supply is completely safe and does not present the ignition or electric shock risk when used in wet conditions or in metal structures. When compressed air is already on site, for example for shot blasting equipment and breathing apparatus, airlamps are ideal. An airlamp's low surface temperature, because of inherent cooling, allows use in a wider range of explosive gases and vapours and eliminates burn risk to workers in close proximity.
Hazard and indication lights -explosion-protected flashing hazard lamps are effective in marking hazards in confined spaces and exits, should lighting fail.
Personal indicators are becoming more common, worn by workers to highlight their position in dark conditions or when visibility is poor. This is now being extended to use on bicycles when conventional cycle lamps cannot be used, such as on petrochemical plants.
Zone 0 lights - The demand for zone 0 light sources is becoming greater. This appears to follow the desire for safer equipment and the demand for lights that can be used in any (unforeseen) circumstance. The majority of zone 0 lamps are battery powered and use lower output LED light sources, which are safer than incandescent bulbs.
Other factors to consider
Purchase cost and cost in service
As part of the selection process for equipment, the user should consider the cost to put the equipment into service (for some items this may include cables, Ex connectors and transformers). Some "Ex" equipment can be hired; this may be the best solution for occasional use, as the maintenance of the equipment becomes the hire company's responsibility. For those intending to purchase equipment, the cost in service may also need to be considered. With smaller items such as torches that are lower cost, but can be purchased in greater volumes, it may be worth considering what the cost in service will be, of both batteries and bulbs. Careful selection of cost effective products with low cost spares can give good savings.
Maintenance
Consideration must always be given to maintenance of "Ex" equipment. Only equipment maintained correctly, and in a good state of repair will offer the protection intended when approval was granted.
Conclusions
A wide selection of specialist "Ex" lighting equipment is available for use in confined spaces and explosive atmospheres. It is critical that equipment is selected and used correctly to give safe and reliable operation.
Note: Some of the references are based on UK practice; equivalent national legislation and recommendations may be available in other countries.
Further information: For a free copy of the "ATEX Explained" Poster Guide, e-mail with contact details including address to atex@wolf-safety.co.uk, or go to www.wolf-safety.co.uk and visit the "ATEX" section to view in electronic form.
You can also call the Wolf Safety Lamp offices on +44 (0) 114 255 1051
