Explosives Inspectorate | Alert | No.116 V 1 | 06 June 2024

Unplanned initiations of loaded blast holes

What happened?

There have been two incidents where electronic detonators experienced unplanned initiation during the energising process, directly prior to firing a blast.

How did it happen?

A formal investigation into the incidents is underway to identify what caused the unplanned initiation.

Key issues

• A blast hole fired during the energisation process immediately before the firing key was applied.
• Blast holes firing before expected can generate projection and vibration hazards causing serious injury.
• Premature firing can impact other blast holes in the shot causing misfires, hole dislocation, and damage to other explosives in adjacent holes.

N.B. The exclusion zone had been cleared and suitably guarded prior to the energisation process in both incidents.

Recommendations

• Faulty explosives articles and equipment have been known to cause premature firing. Sites using electronic blasting systems are advised to remain current with the manufacturer's recommendations.
• When an unplanned imitation occurs:
  • Maintain exclusion zone, carry out a risk assessment and follow expert technical advice;
  • If safe to do so, identify the likely causes;
  • Quarantine suspected explosive articles, including relevant raw components;
  • Commence investigation;
  • Communicate to users’ investigation findings, including quarantining requirements of suspected explosives articles and equipment.
• Quarantining information should include:
  • Specific explosive or equipment details;
  • Storage and handling instructions;
  • Manufacture batch and date information.
• All explosives articles that are quarantined must be secured to prevent inadvertent use, and quarantine should remain in place until all causal factors are identified, and preventative controls have been implemented.
• Blasting risk assessments should include the possibility of an unplanned initiation during the energisation process.

References and further information

Explosive Act 1999

AS 2187.2-2006 Part 2. Use of Explosives