Blasting time

(1) In an underground mine, a specific time shall be set for blasting in order to protect persons from exposure to dust, fumes and smoke. Warning before (2) Before blasting, the blaster shall clear the blast danger zone of all persons; ensure that all entrances to the blast danger zone are guarded by persons to prevent access; and at a surface mine, ensure that an effective audible warning is sounded by a siren or similar device. sequence. (3) Every charged hole shall be fired in its proper sequence, and where any blast could affect other charged blastholes, all of the holes shall be fired in one operation. Blaster to count shots. (4) A blaster shall, when possible, count the number of shots exploding, report the suspicion of any shot that did not fire and identify any misfired hole by inserting a conspicuous, non-metal marker at its outer end or roping off the area. Firing from remote location. (5) Blasts shall be fired from a remote location during shaft sinking operations or when raising has exceeded 10 meters (33 feet). (6) In any blasting operation, the safety fuse shall be at least 1 meter (3.3 feet) in length, be lit by a suitably timed igniting device and if more than one device is used, they shall be activated simultaneously and the safety fuse shall have a burning time at least twice that of the igniting device. Safety fuse lengths. (7) The blaster and all other persons shall leave the blasting area immediately after the ignitor cord or fuses have been lit. Blaster to leave after ignition. (8) Blasting machines shall be of type acceptable to the Inspector and they shall be kept in a cool, dry storage space and maintained in serviceable condition. Blasting machine 128 (9) Condenser discharge machines shall be examined to ensure any residual charge remaining on the capacitors after use is discharged according to the manufacturer’s instructions. Condenser machines. Connecting electrical blasts. (10) The blasting machine shall not be connected to the blasting cables until immediately before firing charges and it shall be immediately disconnected after firing or attempting to fire the charges. Electric power circuits for (11) Electric power from lighting or power circuits shall not be used for firing charges unless the blasting circuit has an isolating transformer and a special firing device that opens the blasting circuit by gravity. Blasting cable size. (12) The blasting circuit conductors shall be No. 12 AWG size cable, or shall be more readily identified as blasting cable and where expendable connecting wire is used, this shall not be less than No. 20 AWG in size. multiple blasting sites. (13) Where a blasting circuit is used for more than one working place, each branch shall be isolated by means of a locked isolating switch that automatically short circuits the branch circuit. Testing electrical circuit. (14) Where more than one shot is fired electrically, the blaster shall test the electrical circuit with an approved circuit testing device immediately before blasting. Electrical storm (15) The manager shall ensure that persons engaged in blasting underground are warned of any electrical storm. Radio transmitters (16) The blaster shall ensure that signs are posted to ensure that radio transmitters shall be turned off when within 20 meters (66 feet) of the site where electric blasting is being used. conductors insulated. (17) All blasting circuit conductors shall be insulated cable and shall be short-circuited except when connecting the blast. 129 (18) Blasting circuit conductors shall be kept at least 150 mm (6 ins) away from power and lighting circuits. Distance of conductors from power lines. Re-entry after (19) The blaster shall ensure that no person enters the blast area until the firing cables have been disconnected from the firing device and short-circuited, and the blaster has sounded an “all clear” signal.