Key features of the final rule include:
•    Provides for MSHA approval of high-voltage continuous mining machines, including better design and construction criteria and improved ground-fault protection. Approval ensures the systems will not introduce an ignition hazard when operated in potentially explosive atmospheres.
•    Establishes mandatory electrical safety standards for proper installation of high-voltage continuous mining machines, electrical and mechanical protection of equipment, handling trailing cables and performing electrical work.
•    Preserves safety and health protections for miners while facilitating the use of advanced equipment designs.
•    Greater protection against electrical shock, cable overheating, fire hazards, and back injuries and other sprains caused by handling trailing cables.
•    Increased safety requirements to eliminate or minimize unsafe work and repair practices, such as handling lighter cables.

Although this equipment has been used in underground coal mines since the late 1990s, mine operators must submit a petition for modification to use it.  Since 1997, MSHA has granted 52 PFMs—with specific conditions—to allow mine operators to use high-voltage continuous miners underground. Currently, there are 27 high-voltage continuous mining machines operating under PFMs in eight underground mines.