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Statement of Need: There are two major types of electrical accidents. One type occurs when a miner inadvertently contacts energized parts. To protect against this hazard, MSHA standards require that electrically powered equipment be deenergized, and power switches be locked out to prevent equipment from being energized, before mechanical work is done; warning signs be posted at the power switch; principal power switches be labeled to show which units they control; danger signs be posted at major electrical installations; and nonconductive material be kept in place at all switchboards and power-control switches where shock hazards exist. ^PThe other type of electrical accident occurs when a miner contacts energized metallic frames or enclosures that are normally not energized. Ground faults occur on the metallic frames or enclosures of electrical mine equipment causing shock hazards to miners. ^PDust, vibration, corrosion, moisture, and heat, coupled with the additional wear and tear associated with the mining process, cause the premature degradation of circuit insulation which leads to ground faults on the equipment. When a ground fault occurs on circuits without an equipment grounding conductor, the frames or enclosures become energized and create a dangerous shock hazard. An effective equipment grounding conductor reduces the shock voltage on the frames or enclosures to safe levels. An equipment grounding conductor is the most critical part of the grounding system. ^PMSHA existing standards 56/57.12025 require that all metal enclosing or encasing electrical circuits be grounded or provided with equivalent protection. The intent of this existing rule is to prevent electrical shock hazards to persons working on or coming into contact with these metal enclosures or metal encased electrical circuits. ^PMSHA's enforcement of existing sections 56/57.12025 has been guided by the Agency's reliance on its own technical experience in electrical grounding as well as using the National Fire Protection Association publication, NFPA No. 70, National Electrical Code (NEC). The NEC is a nationally recognized consensus standard containing electrical safety criteria and procedures accepted throughout the United States. MSHA's reliance on the NEC in the enforcement of sections 56/57.12025 has been questioned by several Federal Mine Safety and Health Review Commission (FMSHRC) judges' decisions. Contractors Sand and Gravel Supply, Inc., 18 FMSHRC 384 (March 1996), Mulzer Crushed Stone Company, 3 FMSHRC 1238 (May 1981), and McCormick Sand Corporation, 2 FMSHRC 21 (Jan. 1980). These decisions have held that section 56.12025 is deficient in several respects. ^PIn response to these decisions, MSHA decided to develop a more effective standard by clarifying compliance requirements for electrical grounding of equipment and enclosures consistent with the NEC which covers all aspects of adequate equipment grounding.

Alternatives: Adopting applicable articles of the 1996 edition of NEC in the proposed rule is an outgrowth of MSHA's longstanding position that compliance with the NEC would provide the most effective protection for miners from electrical shock hazards. Moreover, because the grounding specifications in the NEC are well established and have had few changes in the last twenty years, MSHA believes the applicable articles of the 1996 edition of the NEC would remain in effect for the foreseeable future.

Anticipated Costs and Benefits: MSHA expects costs could be incurred from the purchase of equipment grounding conductors which limit the voltage on non-current carrying metallic parts of equipment. MSHA believes that adoption of the proposed requirements are necessary to prevent shock hazards and would improve miner protection as compared to the existing standard.

Risks: Electrical hazards are a cause of fatal and nonfatal injuries in metal and nonmetal mines. MSHA's accident records related to inadequate equipment grounding supports the need for improved safety standards. An analysis of fatal accidents from 1986 to 1996 reveals that 13 fatalities or 25% of all electrical fatalities in metal and nonmetal mines can be directly attributed to faulty grounding.