Electrical accidents are a leading cause of mining fatalities, accounting for over 6% of deaths between 2000 and 2009, and compared with other industries, mining is among the most dangerous with respect to electrical injuries. With an electrical fatality rate approximately 8 to 9 times that of the average for all industries, mining is on par with construction and even utility industries (2003 to 2007 BLS data). When considering all injuries, including nonfatal, electrical incidents are not nearly as frequent as other sources of traumatic injury in mining. When they do occur however, electrical injuries have historically been disproportionately deadly, with one in every 22 a fatality, compared with an average of 1 in every 203 for all types of injuries in mining (2000 to 2009 MSHA data). The varied nature of mining electrical injuries suggests that no single intervention strategy can eliminate the problem. Instead, multi-faceted approaches that consider engineering and administrative controls, work organization and procedures, protective equipment, and human factors are needed to mitigate electrical hazards. The work in this topic area is supported by the NIOSH Mining Electrical Safety and Communications program. See the NIOSH Mining Products page for software, guides, training materials or other items related to this topic.
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Electrical Accidents Spotlights
U.S. Bureau of Mines/NIOSH Mining Electrical Safety Research: A Legacy of Protection Against Shock, Fires, and Explosions (PDF, 1114 KB, 2010)
This paper reviews the 100-year history of federal electrical safety research in the U.S mining industry, originally by the US Bureau of Mines, and as carried on today by NIOSH.
Understanding and Quantifying Arc Flash Hazards in the Mining Industry (HTM, 3794 KB, 2011)
Arc flash generally refers to the dangerous exposure to thermal energy released by an arcing fault on an electrical power system, and in recent years, arc flash hazards have become a prominent safety issue in many industries. This problem, however, has not been effectively addressed in the mining industry. Mine Safety and Health Administration (MSHA) data for the period 1990 through 2001 attribute 836 injuries to "noncontact electric arc burns," making them the most common cause of electrical injury in mining. This paper presents results from several elements of a recent National Institute for Occupational Safety and Health study of arc flash hazards in mining and provides information and recommendations that can help reduce these injuries. The characteristics of past arc flash injuries in mining are first outlined, such as the electrical components and work activities involved (based on MSHA data). This is followed by a review of important concepts and terminology needed to! understand this hazard. Next, methods for identifying, measuring, and managing arc flash hazards on a power system are covered, with emphasis on recommendations found in NFPA 70E, Standard for Electrical Safety in the Workplace. Finally, results are presented from a detailed arc flash hazard analysis performed on a sample mine electrical power system using IEEE 1584-2004a, focusing on components and locations presenting severe hazards, as well as engineering solutions for reducing the risk to personnel.
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Data & statistics
Electrical Accidents in the Mining Industry, 1990-1999 (PDF, 81 KB, 2003)
This NIOSH study was conducted to focus future research on the most significant electrical problems in the mining industry. Data from 1,926 mine electrical accidents (including 75 fatalities) that occurred between 1990 and 1999 were studied.
Occupational Electrical Injuries in the United States, 1992-1998, and Recommendations for Safety Research (PDF, 214 KB, 2003-08)
Data show that 2,287 U.S. workers died and 32,807 workers sustained days away from work due to electrical shock or electrical burn injuries between 1992 and 1998. The narrative, work activity, job title, source of injury, location, and industry were examined and a primary causal factor was identified for each fatality.
Trends in Electrical Injury in the U.S., 1992-2002 (PDF, 329 KB, 2008-07)
This paper updates an earlier report by the authors that studied electrical injuries from 1992 to 1998. The previous information is expanded and supplemented with fatal and nonfatal injury rates and trends through 2002. NIOSH research aimed at evaluating commercially available overhead power line proximity warning alarms is described.
History
U.S. Bureau of Mines/NIOSH Mining Electrical Safety Research: A Legacy of Protection Against Shock, Fires, and Explosions (PDF, 1114 KB, 2010)
This paper reviews the 100-year history of federal electrical safety research in the U.S mining industry, originally by the US Bureau of Mines, and as carried on today by NIOSH.
Hazards
Understanding and Quantifying Arc Flash Hazards in the Mining Industry (HTM, 3794 KB, 2011)
Arc flash generally refers to the dangerous exposure to thermal energy released by an arcing fault on an electrical power system, and in recent years, arc flash hazards have become a prominent safety issue in many industries. This problem, however, has not been effectively addressed in the mining industry. Mine Safety and Health Administration (MSHA) data for the period 1990 through 2001 attribute 836 injuries to "noncontact electric arc burns," making them the most common cause of electrical injury in mining. This paper presents results from several elements of a recent National Institute for Occupational Safety and Health study of arc flash hazards in mining and provides information and recommendations that can help reduce these injuries. The characteristics of past arc flash injuries in mining are first outlined, such as the electrical components and work activities involved (based on MSHA data). This is followed by a review of important concepts and terminology needed to! understand this hazard. Next, methods for identifying, measuring, and managing arc flash hazards on a power system are covered, with emphasis on recommendations found in NFPA 70E, Standard for Electrical Safety in the Workplace. Finally, results are presented from a detailed arc flash hazard analysis performed on a sample mine electrical power system using IEEE 1584-2004a, focusing on components and locations presenting severe hazards, as well as engineering solutions for reducing the risk to personnel.
Measurement & analysis
Detrimental Effects of Capacitance on High-Resistance-Grounded Mine Distribution Systems (PDF, 3313 KB, 2006-09)
Modern underground coal mines can be very large, having a total connected load in excess of 15,000 hp. These, mines generally have many miles of high-power conveyor belts and 15 or more miles of high-voltage power cables at distribution voltages of 12.47, 13.2, 13.8, or 14.4 kV.This paper addresses the potential detrimental effects of capacitance charging currents during line-to-ground faults in mine power distribution systems. A representative mine power system is modeled, and simulations with faults at various locations are conducted to evaluate the effects of this capacitance on the level of fault current and relay selectivity. This paper also includes results of capacitance measurements made on mine power feeder cables used to validate the simulation model.
Distributed Measurement of Conductor Temperatures in Mine Trailing Cables Using Fiber-Optic Technology (PDF, 63 KB, 1998-03)
Mine trailing cables operated above safe thermal limits can cause premature insulation failure, increasing electrocution and fire hazards. This paper describes a unique approach to measuring temperatures within reeled cable under dynamic test conditions.
Dynamic Temperature Measurement of Overheated Shuttle Car Trailing Cables in Underground Coal Mines (PDF, 220 KB, 1999)
A method is described to measure the conductor temperature of mine trailing cables during normal operation. The temperature is measured using an optical fiber located in the center of the metallic conductors.
From Scotia to Brookwood, Fatal US Underground Coal Mine Explosions Ignited in Intake Air Courses (PDF, 92 KB, 2009-01)
NIOSH researchers studied US underground coal mine explosions over a 30 year period to identify the ignition sources and ignition locations responsible for the most severe explosion events resulting in death. Recommendations are provided for electrical equipment design and installation to prevent future disasters.
Reducing Non-Contact Electric Arc Injuries: An Investigation of Behavioral and Organizational Issues (PDF, 259 KB, 2007-11)
NIOSH investigated behavioral components associated with arc flash incidents in the mining industry and recommended interventions based on the findings.
Engineering controls
Derating Factors - For Round and Flat Mine Trailing Cables (HTM, 2000-08)
Concerns about the present derating factors used for reeled trailing cables prompted researchers at the NIOSH Pittsburgh Research Laboratory to determine new derating factors for reeled coal mining trailing cables. In particular, the new derating factors focus on mine trailing cables used on shuttle cars, with both round and flat cable configurations, that are representative of mining industry usage.
Detection of Downed Trolley Lines Using Arc Signature Analysis (PDF, 2300 KB, 1997-05)
The article discusses the applicability of computerized signal analysis techniques to identify fault currents existing on coal mine direct-current trolley systems
Distinguishing Motor Starts from Short Circuits through Phase-Angle Measurements (PDF, 156 KB, 2002)
NIOSH investigated how the starting of induction motors may cause nuisance tripping of short-circuit protection on coal mine power systems.
Feasibility Study to Reduce Injuries and Fatalities Caused by Contact of Cranes, Drill Rigs, and Haul Trucks with High-Tension Lines (PDF, 122 KB, 2001-05)
Overhead electric power lines present a serious electrocution hazard to personnel in a variety of industries. This paper describes a practical low-cost concept to detect actual contact of mobile equipment with a high-voltage line and provide a warning.
Investigation of Ampacity Derating Factors for Shuttle Cars Using Fiber Optics Technology (PDF, 256 KB, 1997-10)
A method is described to determine dynamically the conductor temperature of reeled shuttle car cables using fiber optics technology.
A Performance Evaluation of Two Overhead Power Line Proximity Warning Devices (PDF, 1318 KB, 2008-11)
This NIOSH publication presents the results of NIOSH testing of two Proximity Warning Devices (PWDs) which are intended to warn personnel if mobile equipment moves within some preselected minimum distance of an energized overhead electrical power line.
Protecting Miners from Electrical Arcing Injury (PDF, 499 KB, 2007)
This paper describes how NFPA 70E - Standard for Electrical Safety in the Workplace can be applied to mining workplaces after an analysis of the mine power system electrical arcing hazards has been completed (and Hazard/Risk Categories determined) using the tables from NFPA 70E or the calculation method as described in IEEE 1584. Appropriate lockout and tagout procedures for use in the mining industry, suggestions for better selection of electrically-rated hand tools, and recommendations for electrical meter selection and use are also discussed.
Training
Noise Exposure and Overhead Power Line (OPL) Safety Hazards at Surface Drilling Sites (PDF, 2464 KB, 2005-11)
This is a series of 5 separate double sided sheets designed to educate workers about noise exposure and overhead power line safety at surface drilling sites.
Videos
Arc Flash Awareness
This video provides information about arc flashes.
Laboratories
Mine Electrical Laboratory
A safe, secure, and properly equipped facility for conducting mine electrical safety research.
Information gateways
Traumatic Occupational Injuries: Electrical Safety
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