EE WAS RACKING IN A 5KV SWITCH TO FINISH MILL AUXILLARY DRIVE. DUST IN THE SWITCH HOUSING MUST HAVE BEEN DISTURBED, CAUSING AN ARC ACROSS CONTACTORS. THE SWITCH EXPLODED OPENING THE DOOR & HIT TING THE EE'S HAND. THE EE FELL BACKWARD AND STRUCK HIS HEAD GETTING A SLIGHT CONTUSION.