Lightning damage to buildings: Addressing the risk

“When lightning strikes” is often used as a euphemism for a rare occurrence. Unfortunately, lightning strikes are far more common than many of us realize — more than 23 million cloud-to-ground strikes occur each year in the U.S., reports the National Weather Service. Their impact to property can be substantial.

Direct lightning strikes in residential and non-residential properties combined cause millions of dollars in fire damages every year, notes the Insurance Information Institute. But that’s just the tip of the lightning bolt. The Lightning Protection Institute (LPI) notes that total business losses related to lightning, either directly or indirectly, can run into the billions. In 2018 alone, almost $1 billion in lightning claims were paid to nearly 78,000 policy holders.¹

In the U.S., two-thirds of the area burned by wildfires is caused by lightning.² Moreover, the Bootleg Fire in Oregon in 2021 created its own weather, which includes fire clouds capable of spawning lightning that could further exacerbate the existing fires.³

Although this article is focused on addressing property damage, it’s vital to recognize lightning’s danger to people. Although the odds of being struck by lightning are extremely low, it remains one of the leading causes of weather-related fatalities, notes the Centers for Disease Control and Prevention.⁴

What is lightning and how is it formed?

Lightning is a giant spark of electricity that originates in clouds or air. The National Severe Storms Laboratory explains that in-cloud lightning, which constitutes the majority of lightning events, occurs entirely within a cloud or clouds or between a cloud and the air. The dangerous cloud-to-ground lightning strikes happen when the negative electricity originating in the atmosphere connects with the positive charge of an object below. When this atmospheric electrical charge is less than a hundred yards from the ground, objects such as trees or buildings send up sparks to meet it. When those sparks connect, the resulting channel creates a huge electric current surge that rapidly travels downward, producing the flashing bolt we call lightning. And it’s fast: Lightning travels at the speed of light or, as NASA notes, 186,000 miles per second.

Lightning can strike anywhere outdoors, but especially on elevated and/or open areas, near water or tall, isolated objects, such as trees. However, it’s important to understand that the tallest object isn’t always the target.

How does lightning damage commercial property?

Lightning can heat the air it passes through to 50,000 degrees Fahrenheit.⁵ That’s five times hotter than the sun’s surface. A lightning bolt can not only cause fires, it also can wreak havoc on exposed equipment on a rooftop or exterior work areas, as well as indoors. Lightning is capable of sending electricity through metal pipes used for plumbing, electrical wires such as landline telephones, and metal reinforcements in concrete floors and walls, the CDC warns.⁶

Complex electronic equipment and computer systems may have an increased exposure to lightning and associated lightning surges. For example, in North America, electronics are designed to use around 120 volts of electricity and can withstand up to 169 volts. A power surge from lightning contains millions of volts, capable of quick destruction.

Does your business include open spaces? Think of airfields, playgrounds, livestock fields and ballparks. Although specific objects, such as airplanes, can be designed to repel lightning, the only way to protect your employees is to make sure they go indoors when lightning is a threat. Thunder is nature’s warning signal for anyone who is outdoors to go inside immediately. Lightning can strike miles from the center of a storm, notes the National Weather Service.

Some points to consider:

• Emphasize to your employees the importance of following these safety measures from the CDC.
• You may also want to consider installing a visual and/or audio warning system.

How do you protect property from lightning?

Most property losses can be dramatically reduced and possibly even eliminated by using proper lightning protection for structures. Guidelines from the National Fire Protection Association (NFPA) and its Code 780 for installing lightning protection systems are considered the national standard by the LPI. These systems create a network of low-resistance paths that can intercept lightning’s destructive electricity and direct it to the ground without impacting the structure and its occupants.

The LPI outlines five elements that need to be in place for an effective lightning protection system. Its “Lightning Protection Overview” includes more detailed information on each of these elements:

• Strike termination devices must be able to accept direct lightning attachment and strikes before the lightning can reach insulated building materials.
• Cable conductors direct the lightning current over and through construction, without damage, between the strike terminations at the top and the grounding electrode system at the bottom.
• Below-grade grounding electrode systems must be able to efficiently move the lightning to its ultimate destination, safely away from the structure and its contents.
• Bonding, i.e., the interconnection of the lightning protection system to other internal grounded metallic systems, must be able to prevent lightning to side flash internally — in other words, stop it from jumping to a lower object (e.g., an individual or another object in the building).
• Surge protection devices must be installed at every service entrance to stop lightning from infiltrating utility lines and transfer the energy into the ground.⁷

Each of these five elements depends upon careful attention to placement, use of proper materials and other considerations. Installation by qualified professionals is crucial.

Every business is unique, but these areas should be evaluated as potentially vulnerable to lightning. Consider ways to mitigate potential damage:

• Critical rooftop equipment
• Complex electronic equipment: Do you have sufficient surge protection for all of these systems?
• Processes, systems or features (such as yard storage of flammable or combustible liquids in tanks, as well as vehicles) that could be set on fire. These should be placed at least 100 yards from the building.
• Solar arrays, or panels
• Tall equipment, such as construction cranes

How should a business respond to damage from lightning?

The best response plan is to be prepared long before an event sidelines your business. Contingency plans should be developed for emergencies, such as fire and severe weather. Plans should include defined duties and functions of various employees and adequate training should be provided.

To help you respond when lightning strikes, consider these tips from Zurich Resilience Solutions:

Develop and implement a formal, written emergency response plan that includes crisis communication procedures and covers all possible scenarios for the specific facility. Ensure the plan is reviewed regularly and any time significant onsite modifications are made. Plans should include defined duties and functions of various employees.

• Provide training for staff on evacuation, intervention and first aid protocols, depending on the specific needs and means available.
• Conduct regular emergency and evacuation drills. Evaluate the results and implement changes/corrective actions as needed.
• Establish a list of contacts for external responders (ambulance, fire brigade, police, hospitals, etc.) and ensure all employees receive a copy.
• Establish a system to notify any affected employee or family member in the event an employee is involved in catastrophic event.
• Conduct a business impact analysis to assess business resiliency.
• Review shutdown and evacuation processes, including data backup and shipping records offsite.
• Create a business continuity plan.
• Limit yard storage and remove flammable items, vehicles and, especially, propane tanks from the property or move them at least 100 feet away from the building.

How can a business recover from lightning?

Many of the steps outlined in our 10-step wildfire recovery plan will pertain to any business dealing with temporary shutdown if a lightning strike compromises their business operations.

Lightning is not the only severe weather threat that could affect your business and property. Here are additional articles offering insights on how to help mitigate, respond to and recover from these events:

Visit the Convective Storm Resource Hub for additional articles offering insights on how to help mitigate, respond to and recover from tornados, hailstorms and convective storms.

1. “The Case.” Lightning Protection Institute. Accessed July 2021.
2. “New Models Predict Fewer Lightning-Caused Ignitions but Bigger Wildfires by Mid-Century.” Oregon State University newsroom. 16 June 2021.
3. Fountain, Henry. “How Bad Is the Bootleg Fire? It’s Generating Its Own Weather.” New York Times. 19 July 2021.
4. “When Thunder Roars, Go Indoors!” National Center for Environmental Health. Centers for Disease Control and Prevention. 21 June 2021.
5. “How Hot is Lightning?” National Weather Service. Accessed July 2021.
6. “Lightning: Lightning Safety Tips.” Natural Disasters and Severe Weather. Centers for Disease Control and Prevention. 14 August 2020.
7. “Lightning Protection Overview: Build & Protect.” Lightning Protection Institute. 19 September 2016.