THE SCOOP WAS BEING USED TO PULL A PIECE OF BELT TOGETHER AT #148 BREAK ON WEST MAINS. SCOOP BACKED INTO A PILE OF ROCK CAUSING THE BATTERIES TO RAISE UP & TWIST. THIS PINCHED 1 OF THE POWER LEADS AGAINST SCOOP FRAME & GROUNDED THE CABLE. THIS CAUGHT THE CABLE INSULATION ON FIRE. FLAMES PRESENT APPROX. 5 MINS. BREAKER WAS KNOCKED & ROCK DUST USED TO EXTINGUISH FLAMES.