LOST POWER ON 001-MMU. UPON INVESTIGATION OF POWER LOSS A FALL WAS DISCOVERED AT SURVEY SPAD 758IN #5 ENTRY ON 1 LEFT MAINS OF 001-MMU. HIGH VOLTAGE CABLE WAS RE-ROUTED AND POWER RESTARTED. FALL WAS TIMBERED OFF AND SUPPLEMENTAL SUPPORT INSTALLED IN OTHER INTERSECTIONS. DIDN'T AFFECT VENTILATION.