(e) Before firing an underground blast, warning shall be given, and all possible entries into the blasting area, and any entrances to any working place where a drift, raise, or other opening is about to hole through, shall be carefully guarded. The blaster shall make sure that all employees are out of the blast area before firing a blast. Table U-1
WARNING SIGNAL-A 1-minute series of long blasts 5 minutes prior to blast signal.
BLAST SIGNAL-A series of short blasts 1 minute prior to the shot.
ALL CLEAR SIGNAL-A prolonged blast following the inspection of blast area.