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Department of Labor
Mine Safety and Health Administration
Accident Info-Gram
March 2004
Track Hoe Causes Electrical Arc Incident
Recently, a contractor at a southern Illinois surface mine was working below energized high-voltage lines when his track hoe came close enough to the overhead lines to cause an electrical arc, short circuit. The contractor was operating a Cat 330L track hoe placing and moving rip rap on a drainage ditch. The overhead power lines were energized at 69,000 volts and were located approximately 21-feet above the ground. The operator estimated he was not close enough to contact the overhead power lines. A large flash occurred and the power to the preparation plant, synfuel plant, and adjacent underground mine was interrupted. There were no injuries or property damage as a result of this close-call incident.
BEST PRACTICES
- Recognize potential hazards. Train workers to "Look up" prior to starting work.
- Install physical barriers under overhead lines.
- Erect signs to identify a danger zone.
- Raise problem sections of overhead line to at least 40 ft. above ground.
- Have the electric power utility company install insulating barriers or sleeve conductors where equipment must operate.
- Have high visibility spheres installed on energized lines to help make the line location obvious to all workers.
- Have the electric power utility company temporarily de-energize the power lines.
- With instrumentation determine height of power lines before performing work close by.
- 77.807-2 requires booms and mast shall not be operated within 12 feet of an energized 69 KV line.
- Electric power utility companies will reclose 3 times. If power lines are contacted, stay in or on equipment until power is off.
This information was provided by concerned
miners in an effort to eliminate accidents. Accident or "close
call" information within District 8 may be shared by contacting
the MSHA office at (812) 882-7617.
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