LED Mine Lighting and Worker Safety|
Article- January 2012 By Larson Electronics.com
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Underground mining is one of the most dangerous industrial professions, with a host of issues which provide a great deal of potential for a variety of hazardous or lethal conditions. The inherent lack of ambient light and conditions ranging from surfaces with poor reflective properties to poor object contrasts, to confined spaces and hazardous vapors and gases, all contribute to create an extremely hazardous workplace. These are just a few representative examples of the problems facing the modern mine worker, and addressing and dealing with these potentially injurious issues effectively is critical if mining professionals are to perform their jobs not only effectively, but safely. Until recently, the primary form of lighting for mine workers has been the cap lamp, providing them a portable and easily directional light source which allows them to detect potential hazards during the course of their operations. However, research suggests such lighting is inadequate and in part responsible for a notable number of reported incidents and accidents. Improving the effectiveness of mine lighting has thus been an issue of some recent study, and recent reports suggest that newer solid state lighting such as LEDs may hold the potential to significantly reduce the number of serious incidents.
Effective mine lighting serves not only to illuminate the underground work area, but assist workers in noting and identifying potential ground fall hazards, machinery threats, and slipping, tripping and collision hazards. Lighting is critical in mining safety due to the fact that workers in mines rely primarily on vision to detect hazards despite the poor lighting levels encountered within the mining environment. A substantial portion of the threats encountered by miners involve slips, falls, and tripping over objects. It’s considered likely the reason for this stems from weak lighting and the poor contrast of objects and materials contained within the mines due to their often rock and-or earth composition and poor reflectivity. With mines often being extremely noisy and communication as well as visual observation difficult, inadequacies in lighting can pose serious risks and potentially lead to an increase in the odds of accidents occurring.
For these reasons and more, it is extremely important that mine lighting be effectively designed and chosen according the conditions under which it will be operated. Older lighting designs which depend upon incandescent lamps carry several shortcomings which limit their effectiveness, but until recently there have been few more effective alternatives available. As well as providing lighting capable of producing the least glare and best contrasting possible, providing power for such equipment is also a challenge. Mining equipment does not often lend itself well to acting in dual roles as both industrial machinery and power source, and the incandescent cap lamps worn by miners are plagued with issues of short battery life and diminishing lamp effectiveness as batteries run low. It has been shown that a cap light can lose 35% of its effective output within 8 hours of operation, suggesting that not only are current cap lamps inefficient, but that they also contribute to a steady increase in potential hazards the longer they are operated without fresh batteries or recharge.
A fairly recent CDC study considered the effectiveness of LEDs as compared to standard mining cap lights and came away with interesting results. Utilizing controlled tests involving standard mining cap lights, common commercial grade LEDs, and a special LED mining light design of their own making, they found that for most intents and purposes, LEDs provided a greater degree of contrast and improved threat detection times as shown by test subjects. Particularly in the case of workers over the age of 40, with 43 years being the average age of mine workers, contrasting of LED illuminated objects was improved 43%. Additionally, threat detection times increased 11-14% as well with LEDs as compared to baseline incandescent cap lights. There were no increased complaints associated with glare, and overall suggestions derived from the study are positive, with good potential for increased safety and performance in mining operations as a result of implementing LEDs. An added result of testing found further potential improvement from the extended runtimes found with LED based lighting equipment as well. While incandescent mining cap lights experienced a 35% decline in output over the course of 8 hours, LED versions demonstrated a mere 3% drop, further suggesting that not only do LEDs improve workers visual acuity in mining conditions, but that they maintain that improvement longer.
Currently, LED development has reached the point where LED illumination is now not only effective for large scale applications, but can also be applied to hazardous locations and conditions in equipment rated to explosion proof and HAZLOC standards. With their high durability and low current requirements, LEDs are well suited to the low voltage applications in mining where battery and equipment power represents the dominant power sources available. Their durability affords greater resistance to the abusive conditions of a mine, offering greater protection against illumination failures and thus increased hazard. The biggest setback, at least according to the CDC study, appears to be the uneven standardization among LED lighting devices. LEDs with higher color rendering indexes are shown to be the most effective for improving contrasting, so LED equipment designed to produce a truer rendition of colors should be applied to mining applications to obtain the best results. Currently, federal energy and safety agencies are working to craft new guidelines that will improve standardization among LED manufacturers, which should theoretically only improve the availability of viable LED options and weed out substandard LED varieties.
At the most basic level, the crux of improved mine lighting rests on producing more light of better quality. Several studies already prove the ability of LED lighting to enhance worker productivity, alertness, and safety with increased light levels and higher contrast thresholds. With the rapid evolution of LEDs continuing at a steady pace, new designs and methods of applying LEDs continue to appear as fast as every four months. This rapid development has already elevated LEDs to a level more than adequate for mining applications and in fact represents a substantial improvement over current mine lighting technology. As has already been proven in most types of industrial applications, mining operations may also stand to gain substantial benefits from LED technology ranging from reduced incident reports and fatalities to increased productivity.