Mining Topic: Electrical Safety

An electrician using a meter to test a 480V circuit, while wearing electrically-rated gloves, an arc-rated face shield, and an arc-rated protective jacket.

What is the health and safety problem?

Electrical accidents are a leading cause of mining fatalities, accounting for over 6% of deaths between 2000 and 2009.

What is the extent of the problem?

Compared with other industries, mining is among the most dangerous with respect to electrical injuries. U.S. Bureau of Labor Statistics data for 2003 to 2009 reveal that the mining industry has an electrical fatality rate approximately 8 to12 times the rate for all U.S. industries. Considering both fatal and non-fatal cases, electrical injuries are disproportionately deadly. Mine Safety and Health Administration data for 2000 to 2009 show one fatality for every 22 electrical-related injuries, compared with an average of one fatality for every 203 injuries for all other injury types in mining.

How is OMSHR addressing this problem?

Researchers at the Office of Mine Safety and Health Research (OMSHR) continue to address the prevention of mining electrical injuries over the years with numerous studies focusing on innovative power system design, engineering and administrative controls, work organization and procedures, protective equipment, and human factors. Much of this work utilized the OMSHR Mine Electrical Laboratory.

What are the significant findings?

Research findings have included methods to avoid electrical cable hazards, improved power system grounding, techniques for preventing electrical ignitions which could lead to fires and explosions, recommendations for improved overhead electrical power line safety, strategies for mitigating arc flash hazards, and better understanding of electrical accident causes.

What are the next steps?

Future electrical safety research by OMSHR will continue to address issues and hazards that have been linked to many past electrical injuries, as well as potential hazards from new technology. Examples include shock and burn hazards associated with switching equipment and cables, accidental overhead power line contacts, improved training, battery safety, and equipment permissibility.

Noteworthy Publications & Products

A Performance Evaluation of Two Overhead Power Line Proximity Warning Devices (2012-08)
The results of NIOSH's test of two commercially available proximity warning devices (PWDs) are presented. PWDs warn personnel if mobile equipment moves within some preselected minimum distance of an energized overhead electrical power line.
Arc Flash Awareness (2012-09)
This video focuses on individual and organizational behavior related to arc flash events over an 11-year period in the mining industry.
Derating Factors for Round and Flat Mine Trailing Cables (2012-09)
Concerns about the present derating factors used for reeled trailing cables prompted researchers at the NIOSH to determine new derating factors for reeled coal mining trailing cables.
Detrimental Effects of Capacitance on High-Resistance-Grounded Mine Distribution Systems (2012-08)
There are 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.
Distinguishing Motor Starts from Short Circuits through Phase-Angle Measurements (2012-08)
NIOSH investigated how the starting of induction motors may cause nuisance tripping of short-circuit protection on coal mine power systems.
Electrical Accidents in the Mining Industry, 1990-1999 (2012-08)
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.
From Scotia to Brookwood, Fatal US Underground Coal Mine Explosions Ignited in Intake Air Courses (2012-08)
NIOSH researchers studied U.S. underground coal mine explosions over a 30-year period to identify the ignition sources and locations responsible for severe explosions resulting in death, and provided recommendations for safer electrical design.
Trends in Electrical Injury in the U.S., 1992-2002 (2012-08)
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.
U.S. Bureau of Mines/NIOSH Mining Electrical Safety Research: A Legacy of Protection Against Shock, Fires, and Explosions (2012-08)
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 (2012-08)
Noncontact electric arc burns are the most common cause of electrical injury in mining according to data for 1990 through 2001. Results from a NIOSH study of arc flash hazards in mining and recommendations to reduce these injuries are presented.