Lightning During Blast Loading: What Blasters Must Do and Watch For

Lightning During Blast Loading: What Blasters Must Do and Watch For

Lightning is one of the most dangerous hazards you will face while loading a shot. A single strike — or even a nearby bolt — can send enough energy through the ground or wires to initiate electric detonators and cause a premature detonation. When lightning is in the area, there is no time to think twice.

Rule #1: When thunder roars — or lightning is seen — stop everything immediately.

 You cannot beat lightning. The smartest move is almost always to stop early, get everyone to safety, and fire what is already loaded if you have the chance. A controlled partial shot is far better than an uncontrolled lightning-induced detonation.

Stay alert, trust your lightning detection system, and never take chances with thunder.

When in doubt — clear out.

What to Watch For

• Dark clouds are building or moving toward the shot
• First flash of lightning (even if far away)
• First rumble of thunder
• Lightning detection system showing strikes within 10–20 miles (follow your site’s exact trigger distance)
• Sudden wind shifts or rain that often come with thunderstorms
• Static electricity on equipment or in the air (especially in dry conditions)

Never assume “it’s still too far away.” Lightning can strike 10–15 miles from the main storm.

Immediate Actions – Step by Step

1. Stop All Loading Activities Right Now
   • Put down primers, boosters, and explosives.
   • Do not continue loading even one more hole.
   • If you have detonators in your hands, shunt the leg wires immediately.
2. Evacuate the Blast Area
   • Clear every person from the shot, loaded holes, and the entire blast zone.
   • Use the same clearing distance and guarding procedures you would use before firing the shot.
   • Move quickly but calmly to a safe shelter: – a substantial building with plumbing and wiring, or – a hard-topped metal vehicle with windows rolled up (no convertibles or open trucks).
3. Decide Quickly – Fire the Loaded Holes If Possible. This is often the safest option when lightning is approaching, and you already have holes loaded:
   • If you can safely clear the area and fire the shot (or at least the loaded portion), do it.
   • Many experienced blasters prefer to shoot a partial pattern rather than leave primed holes sitting in the ground during a storm.
   • Make sure you have proper warnings, guards on all roads, and everyone is at a safe distance before initiating.
4. If You Cannot Fire
   • Secure the site.
   • Post guards to keep people out.
   • Leave the area completely.
5. Wait Before Returning
   • Stay out of the blast area for at least 30 minutes after the last thunder or lightning is seen or heard.
   • Many companies use 30–60 minutes as standard policy.
   • Only return once your lightning detection system shows the storm has clearly moved away.
6. Inspect Before Resuming Work
   • Walk the pattern carefully.
   • Look for any signs of damage, blown-out holes, misfires, or detonators that may have shifted.
   • Re-check connections and stemming before continuing to load.

Extra Things to Watch For in the Field

• Electric detonators are especially vulnerable — treat every loaded hole as “live” during a storm.
• Non-electric systems (shock tube, detonating cord) are safer but not completely immune if a direct strike hits the pattern.
• Dry, rocky ground can conduct stray currents farther than you expect.
• Tall equipment (drills, excavators, cranes) near the shot can act as lightning attractors.
• After a strike, ground currents can remain dangerous for several minutes.

Field Checklist – Lightning During Loading

• Lightning or thunder detected → Stop loading immediately
• Shunt any exposed detonator leads
• Evacuate the entire blast area using full shot-clearing distances
• Decide: Fire loaded holes now (if safe) or secure and leave
• Move to a proper shelter (building or metal vehicle)
• Wait a minimum of 30 minutes after the last thunder/lightning
• Inspect all loaded holes before resuming work
• Document the stoppage and actions taken

This is practical field guidance only. Always follow your company’s Lightning Safety Plan, site-specific blasting regulations, MSHA/OSHA rules, and the direction of your Blaster-in-Charge. Life safety comes before production every single time.