EE WAS HELPING OTHERS INSTALL A SPLICE IN THE TROLLEY WIRE ALONG THE 28 WEST MN TRACK. THE TROLLEY WIRE PULLED OUT OF THE SPLICE AND STRUCK THE EE ON THE UPPER LEFT LIP, LACERATING THE LIP AND BRUISING HIS TEETH. EE FAILED TO KEEP HIS BODY CLEAR OF THE TROLLEY WIRE WHILE MAKING THE SPLICE, AS HE HAS BEEN TRAINED TO DO. THERE WAS NO DAMAGE OR IMPAIRMENT TO MINING EQUIP OR OPERATIONS