A rational approach to underground roadway lighting

"Low-pressure sodium light sources have been available for several years, but have not received wide acceptance in underground mining. This is because they are difficult to operate using DC power, they are not an intrinsically safe light where explosive gases may be encountered and they give poor colour rendition.With the need for energy conservation, several Canadian hard-rock metal mines are now changing their lighting to low pressure sodium, as it has the highest efficacy of any light source in terms of lumens per watt. Studies have pointed out several other advantages as well. Glare can be controlled, they penetrate fog well, they are easily maintained, they have a long life and they give the highest visual acuity when compared to other types of lighting. As well, in an underground mine, contrast is much more important than colour for task identification. For close work, the colour problem is alleviated with the use of cap lamps.Case studies are presented from Canadian practice. These show how the lights are modified for underground use, calculations preceding light installation, and how and where the lights are installed in the underground environment. Mention is made of worker reaction to the lights and possible physiological effects.IntroductionThe importance of good underground lighting to the total environment of mining cannot be overemphasized. In addition to the obvious benefits of improved worker morale, available studies show that good lighting practices reduce accident severity and frequency as well as increase production."