Shot Firing Equipment and Initiation Systems
Candidates must know the main initiation systems: safety fuse with detonating cord and plain detonators, electric detonators (instantaneous and delay), and non-electric (shock tube) systems, plus electronic detonators. For each, know the advantages, the failure modes, and the safety precautions.
Electric firing raises specific hazards: stray currents, static, radio frequency, lightning, and the risk of premature initiation. Test circuits with an approved blasting galvanometer or circuit tester, keep the firing circuit isolated until the shot, use a shunting procedure, and ensure the exploder or firing switch is under the shotfirer's sole control. Understand series versus parallel circuit testing and why series is preferred for continuity checking. Non-electric systems remove the electrical hazard but introduce handling and cut-off risks; shock tube must be protected from damage, kinks and heat.
Electronic detonators offer timing accuracy and testability but require correct programming, logging and secure handling; a common question traps candidates on what testing is permissible before connection.
Rule of thumb: the firing point must be under the shotfirer's direct control, with the exploder key or firing switch in their personal possession, and the circuit shunted until the moment of firing.
Worked example: before connecting the shot, the shotfirer confirms no thunderstorm is approaching, suspends all radio transmissions near electric detonators, tests each circuit, and keeps the exploder key on their person throughout.