AN UNINTENTIONAL ROOF FALL OCCURRED ON THE NO. 3 CABLE ENTRY @ 22 ROOM ALONG 4 WEST HAULAGE. THE FALL OCCURRED AT AN INTERSECTION. APPROX. 8' HIGH AND 18' WIDE. THE 4160AC HIGH VOLTAGE CABLE W AS CAUGHT UNDER THE FALL AND HAD TO BE REROUTED. THERE WERE NO INJURIES NOR WAS VENTILATION AFFECTED.