SEA/General/TBT-SEA-004

Lightning Strike Procedures

Seasonal & Weather › General › Lightning Strike Procedures

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Lightning strikes kill and seriously injure construction workers who are exposed on open sites during thunderstorms.
Tall structures, cranes, scaffolding, and steel frames attract lightning — workers on or near them are at extreme risk.
The 30/30 rule applies: if the time between lightning and thunder is 30 seconds or less, seek shelter immediately.
Work at height, crane operations, and work on exposed structures must cease at the first sign of an approaching storm.
Safe shelter means a substantial building or a vehicle with a metal roof — site cabins, containers, and enclosed vehicles qualify.
Open-sided shelters, scaffolds, lone trees, and temporary structures do not provide adequate lightning protection.
Workers should not resume outdoor work until 30 minutes after the last observed lightning or thunder.
Lightning can strike up to 10 miles ahead of a storm — blue sky overhead does not mean the risk has passed.
A lightning risk assessment should be carried out for exposed sites, identifying safe shelters and evacuation triggers.
Mobile phone weather apps and lightning detection services provide advance warning of approaching electrical storms.

Fatal strikes	Lightning delivers up to 300 million volts — a direct strike is almost always fatal, and near-strikes cause severe burns and cardiac arrest.
Tall structure risk	Cranes, scaffolds, and steel frames are the highest points on site — lightning seeks these structures and anyone touching them.
Delayed danger	Lightning strikes ahead of the visible storm — waiting until rain arrives before stopping work leaves workers exposed too long.

Don't

Monitor weather forecasts and lightning warnings before and during each shift.
Apply the 30/30 rule — seek shelter when lightning-to-thunder gap is 30 seconds.
Stop crane operations and work at height at the first sign of thunderstorm approach.
Identify safe shelters including buildings and metal-roofed vehicles at your work area.
Move to shelter immediately when the storm trigger is activated — do not wait.
Wait 30 minutes after the last lightning or thunder before resuming outdoor work.
Stay away from tall structures, cranes, scaffolds, and metal fences during storms.
Avoid open ground, hilltops, and exposed ridgelines during electrical storm activity.
Brief workers on lightning procedures and shelter locations during the site induction.
Use lightning detection services for advance warning on exposed or remote sites.

DON'T ignore approaching thunderstorms — monitor forecasts and act on warnings.
DON'T continue working if the lightning-to-thunder gap is 30 seconds or less.
DON'T operate cranes or work at height during thunderstorm conditions.
DON'T shelter under lone trees, open scaffolds, or temporary open-sided structures.
DON'T delay seeking shelter — lightning can strike before rain arrives.
DON'T resume work less than 30 minutes after the last observed lightning or thunder.
DON'T touch metal structures, fences, or equipment during a thunderstorm.
DON'T remain on open ground or elevated positions during electrical storm activity.
DON'T assume workers know the lightning procedure — brief them during induction.
DON'T rely on visual observation alone — use weather apps and detection services.

See also: Working in High Winds | Summer Heat and Hydration

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