DRIVER DUMPED HIS LOAD & PULLED OUT OF STOCKPILE AREA W/HIS TRUCK BODY IN THE UP OR DUMP POSITION. HE TRAVELED APPROX. 170'BEFORE CROSSING ONTO MINE PROPERTY AGAIN & TRAVELED APPROX. 30'BEFORE CONTACTING 600 VOLT OVERHEAD POWER LINES. THE DRIVER REMAINED IN THE TRUCK FOR APPROX. 45 MINUTES UNTIL CONDITIONS WERE DEEMED SAFE FOR HIM TO EXIT. HE WAS NOT INJURED.