Introduction: Electric blasting systems deliver controlled current from a blasting machine to detonators to initiate explosive charges. The main components are the blasting machine, lead/connecting/leg wires, detonators, and test instruments.

Body: Components & Checks

• Blasting Machine: This can be a generator (twist/push) or a capacitor-discharge type. It provides a controlled energy pulse. It should only be repaired by the manufacturer.
• Wires: Includes the main Lead/Firing Wire (≥14 AWG), Connecting Wire (~20 AWG), and Leg Wires attached to the detonator. Leg wires have a protective shunt that must remain until final connection.
• Test Instruments: A Blasting Galvanometer or Blaster's Ohmmeter is essential. These contain limiting resistors to test circuit continuity and resistance without firing the detonators.
• Circuit Types: A simple Series circuit is most common. Series-Parallel circuits allow more caps but require careful resistance balancing.
• Pre-firing Checks:
  • Examine the entire circuit with an approved meter to check for continuity (no opens) and correct resistance (no shorts).
  • Ensure all personnel are cleared from the blast area to a safe standoff distance (typically ~500 ft).
  • Visually inspect all splices to ensure they are taped and kept off the ground.
  • Survey the area for stray currents or active radio transmitters.
  • Confirm the blasting machine is locked or secured until the final connection is made.

Conclusion: Adherence to manufacturer guidance, proper checks with approved instruments, and following all relevant DGMS regulations are critical for ensuring a safe and effective blast.