29.H.04 Safety Signals.
- All blasting operations must use the following safety signals:
- (1) WARNING SIGNAL - a one-minute series of long audible signals 5 minutes prior to blast signal;
- (2) BLAST SIGNAL - a series of short audible signals 1 minute prior to the shot; and
- (3) ALL CLEAR SIGNAL - a prolonged audible signal following the inspection of blast area.
- The safety signals must be given by use of a compressed air whistle, a horn, or equivalent means, and must be clearly audible at the most distant point in the blast area. The boat whistle on a drill boat must not be used as a blasting signal.
- The code for safety signals and warning signs and flags must be posted at all access points.
- Employees must be made familiar with the signals and instructed accordingly.
29.H.05 The person making leading wire connections must fire the shot. All connections must be made from the borehole back to the source of firing current and the leading wire must remain shorted and not be connected to the blasting machine or other source of current until the charge is to be fired.
29.H.06 After firing an electric blast, the leading wires must be immediately disconnected from the power source and shunted.
29.H.07 When firing a circuit of electric blasting caps, care must be exercised to ensure that an adequate quantity of delivered current is available in accordance with the manufacturer's recommendations.
Knowledge Check Choose the best answer for the question.
29-12. Which of the following signals sends a series of short audible signals 1 minute prior to the shot.
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