Department of Labor
Mine Safety and Health Administration
Truck Contact with High Voltage Line
On Thursday, January 29, 2009, a high-voltage near-miss electrical incident occurred at a District 8 mine. A truck driver came on mine property to load his truck, and while in the scale area, raised his trailer bed to remove ice from the tarp. The truck bed contacted the 7200 VAC overhead power lines that supplied power to the scales. A security guard in the area observed an electrical arc to the truck bed. At the point of contact with the raised truck bed, the high-voltage conductor height was 26 feet. After the truck driver saw a flash, he lowered the bed. With the bed lowered, the highest point on the truck was 11.5 feet. The high voltage line was clearly marked with signs indicating "Danger High Voltage Overhead." 30 CFR § 77.807-2 requires that "The booms and masts of equipment operated on the surface of any coal mine shall not be operated within 10 feet of an energized overhead powerline." 30 CFR § 77.807-2 extends the requirement to equipment required to pass under or by high-voltages line. Voltages of 69,000 volts or higher require greater clearances. Although this was a power company line, it did not automatically re-energize after the power kicked from contact with the truck bed, which is usually the case. To restore power to the scale area, the power company replaced a fuse in their system.
- Study worksite each time you move equipment, especially when you are operating equipment in areas used for storage, stockpiling, or any areas of low power line clearance.
- If vehicle contacts power lines, lower bed to break contact with power line, if possible.
- If vehicle contacts power line, STAY IN VEHICLE until it has been verified that the power is de-energized. If the power line is a utility company line, even though it appears that the power is off, it still may be energized because utility company power line protective devices normally re-close (re-energize) three times to clear any faults. Because of the re-energizing the power lines, an electrocution could occur when exiting the vehicle.
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.