4.8.3. If there has been one or more misfires or if there is any doubt that all shots have fired or if an explosion follows one or more misfires, no one shall return to the scene within 30 minutes of the time:(a) the last detonation was heard or the last detonation was expected, when using a safety fuse for firing; or
(b) the blasting current was applied, when firing electrically.