The Mine Safety and Health Administration (MSHA) issued the final rule permitting the use of high-voltage longwall mining equipment in underground coal mines. Applicable to longwall equipment that uses between 1,001 and 4,160 volts, the rule contains provisions that will protect miners from electrical hazards as they use or work near the equipment.
"Regulations governing miner health and safety must reflect advances in technology in order to be truly effective," said Dave D. Lauriski, assistant secretary of labor for mine safety and health. "The new rule provides for a more efficient and effective use of mining equipment and resources and simultaneously provides maximum protection for workers in the mining environment."
Longwall mining is a technique to extract coal that uses machinery that shears coal along an underground wall approximately 1,000 feet wide. It drops the coal on conveyor belts or other equipment to be transported up to the surface. Technological advances over the past quarter of a century have introduced high-voltage equipment on longwall mining systems, which has increased production of longwall systems.
Under current MSHA regulations, longwall mining equipment is only permitted when the equipment uses medium- to low-voltage electrical power. High-voltage longwall equipment is only permitted on a case-by-case basis through MSHA's petition for modification procedures.
In issuing the final rule, MSHA concluded that based on the high-voltage equipment use experience under granted mine-by-mine petitions, the equipment can be used safely, provided certain conditions are met. The new rule provides for, among other actions, the use of insulated cable-handling equipment; use of protective gloves to troubleshoot and test low- and medium-voltage circuits associated with high-voltage circuits; and the use of barriers and interlock switches to help guard against contact with energized circuits. The rule also requires the use of cables containing metallic shielding (SHD) around each power conductor.
edited by Sandy Smith ([email protected])