from National Weather Service
Some workers are at greater risk than others. People who work outdoors in open spaces, on or near tall objects, with explosives or with conductive materials such as metal have a greater exposure to lightning risks. Workers in these occupations face the most risk:
Explosive handling or storage
Heavy equipment operation
Plumbing and pipe fitting
Construction and building maintenance
Farming and field labor
Telecommunications field repair
Power utility field repair
When thunderstorms threaten, don't start anything you can't quickly stop. Pay attention to the daily forecasts so you know what to expect during the day. Also pay attention to early signs of thunderstorms: high winds, dark clouds, rain, distant thunder or lightning. If these conditions exist, do not start a task you cannot quickly stop.
Know your company's lightning safety warning program. Businesses that have high risk functions, such as explosive storage or field repairs, should have a formal lightning warning policy that meets two basic requirements:
Lightning danger warnings can be issued in time for everyone to get to a safe location
Access to a safe place
Assess your lightning risk and take appropriate actions. During thunderstorms no place outside is safe. If you can hear thunder, lightning is close enough to strike. Stop what you are doing and seek safety in a substantial building or a hard-topped metal vehicle.
Know what objects and equipment to avoid during a thunderstorm.
Stay off and away from anything tall or high, including rooftops, scaffolding, utility poles and ladders.
Stay off and away from large equipment such as bulldozers, cranes, backhoes, track loaders and tractors.
Do not touch materials or surfaces that can conduct electricity, including metal scaffolding, metal equipment, utility lines, water, water pipes and plumbing.
Leave areas with explosives or munitions.
If a co-worker is struck by lightning. Lightning victims do not carry an electrical charge, are safe to touch, and need urgent medical attention. Cardiac arrest is the immediate cause of death for those who die. Some deaths can be prevented if the victim receives the proper first aid immediately. Call 9-1-1 and perform CPR if the person is unresponsive or not breathing. Use an Automatic External Defibrillator if one is available.
For more information, see Lightning Safety When Working Outdoors: OSHA Factsheet