What to do during a lightning storm

According to the National Weather Service, lightning strikes within the United States approximately 25 million times a year and kills an average of 51 people, severely injuring hundreds more. It’s responsible for approximately 1 billion dollars of annual loss for the insurance industry, damaging both machinery and equipment. A single bolt can contain up to one billion volts of electricity and reach air temperatures of 50,000°F. Florida is the lightning capital of the U.S. and has the most lightning-related deaths annually.

If the University of Florida Lightning Research Center’s theory of global warming proves to be correct, we could see double, or even triple, the amount of lightning activity in the next 50 years.

Here are some tips on what you should do during a lightning storm:

  • Do immediately move to safe shelter when you hear thunder. This could be a building with electricity and plumbing, or an enclosed metal-topped vehicle with the windows rolled up. Stay at that safe shelter at least 30 minutes after you hear the last sound of thunder.
  • Do avoid plumbing, including sinks and baths, along with windows, doors, and porches during the storm.
  • Do stay away from anything that conducts electricity such as power lines, metal fences, or utility poles. While inside, stay off corded phones, computers, and other electrical equipment.

Cloud-to-ground lightning bolts begin when a step-like series of negative charges, called a stepped leader, race downward from storm clouds to Earth at about 220,000,000 mph. A leader forms a path of ionized air moving towards the opposing charge. It can move in a single path with no branches, or it can move in steps and branch out.

After seeing a flash of lightning, try counting the number of seconds until you hear thunder. Every five seconds represents one mile of distance away. Divide the number of seconds you count by five to get the number of miles away that lightning struck. This delay is because the speed of sound (1,088 feet/sec) is much slower than the speed of light (186,291 miles/sec).

Here’s what you should avoid when lightning strikes:

  • Don’t lie on concrete floors or lean against concrete walls.
  • Don’t take shelter under an isolated tree or lie flat on the ground outside.
  • Don’t take shelter in a swimming pool, lake, river, etc. Get out of the water immediately!
  • Don’t take shelter on a hill or elevated area. Lightning tends to strike the highest and least resistive point.

Since 2001, U.S. fatalities due to lighting have dropped, mainly due to the greater awareness of the danger of lightning. Remember, no place outside is safe from lightning when thunderstorms are in the area. If you hear thunder, lightning is nearby and close enough to strike, so you should seek shelter immediately.

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© 2018 The Hartford Steam Boiler Inspection and Insurance Company. All rights reserved. This article is for informational purposes only and does not modify or invalidate any of the provisions, exclusions, terms or conditions of the applicable policy and endorsements. For specific terms and conditions, please refer to the applicable coverage form.

Vincenzo Pagliuca

Vincenzo Pagliuca is a Principal Electrical Engineer for Hartford Steam Boiler Inspection and Insurance Company. Vincenzo assists the claims and underwriting departments by providing corrective action and risk solutions utilizing his expert knowledge and technical background. He has over 23 years of experience in electrical engineering as well as research and development.

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