206Audible warning system—general blasting

206 Audible warning system—general blasting This is the audible warning system for use in above-ground blasting operations other than in a mine or quarry: (a) 1 minute before firing, an audible signal must be sounded for 15 seconds; (b) the signal ‘Fire on!’ must be given immediately before the charge or charges are fired; (c) for the ‘all clear’, 3 short audible signals must be sounded for 1 second each, separated by 1 second.