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What Happens When Lightning Strikes a Building? Lightning Rods, Conduction, and Grounding Explained

As one of the oldest observed natural phenomena, lighting is intense, beautiful, and terrifying. The basic mechanics of the sky-born discharge are easy enough to comprehend — air is an insulator for areas of positive and negative charges, which build until they reach a level that breaks down the insulator, causing a rapid discharge of electricity.

Tall objects, like skyscrapers, often produce connecting sparks and provide channels for lightning to travel to the ground. Exactly what happens when lightning strikes a building, and what do property owners and managers need to know to protect their buildings?

What Happens When Lightning Strikes a Building Without Protection

Dangerous Power

A lightning strike packs a powerful punch in a fraction of a second. Traveling around 270,000 mph, a single bolt or flash carries about 300,000,000 volts or 30,000 amps. The typical current for a household is 120 volts or 15 amps.

Without lightning rods or newer protection systems, a building and its tenants are vulnerable to damage and injury. If the bolt has no safe and effective channel to travel to the ground and disperse, it will hitch a ride on any conductive surface, including electrical wiring and plumbing. Residents, tenants, and staff are also potentially good conductors of electricity, due to 70% of the human body being water.

Fires

The tremendous and rapid infusion of electricity into a structure can create spontaneous electrical fires. Lighting heats the surrounding air to 50,000°F, five times the temperature of the surface of the sun. While the heat alone is enough to melt or cause fires, the massive surge of electricity often produces sparks, igniting nearby flammable materials.

Moreover, what happens when lightning strikes a building is not always contained to the structure that was hit. A single strike to an unprotected building can also cause fires indirectly related to the initial flash. Lightning typically occurs during thunderstorms and other severe weather. High winds can push sparks and embers to other properties or structures, spreading the blaze like a contagion.

Electrocution

Any person within a lightning-struck building or in the vicinity is at risk of electrocution or shock. Lightning can spread out about 20 meters after striking the earth. Still, this distance can be farther or shorter depending on environmental characteristics, which is why staying indoors and away from conductive materials is safest.

That said, the best way to protect your property and the people who use it is with a proper lightning protection system. While lightning rods are standard, the system should be updated to a charge transfer system or early streamer emitter air terminal.

What Happens When Lightning Strikes a Building With Protection

Lightning Rods: The Classic Form of Protection

Benjamin Franklin is the inventor of the lightning rod, a simple but effective means of safely dispersing a massive electric charge. These rods are about an inch in diameter and connect to a piece of aluminum or copper wire, also an inch in diameter, that runs the entire length of the building. The wire attaches to a conductive grid buried underground near the structure.

Conduction refers to the movement of electric particles through an appropriate transmission medium. A rod is a conductor and is also known as an arrester.

Despite popular belief, lightning rods do not attract lightning. Instead, the construction provides a low-resistance and direct path to the ground. Grounding works because electricity wants to flow down a negatively charged “stepped leader” toward the ground. The grounding wire provides a path of least resistance.

Even with a lightning rod in place, when lightning strikes a building, it is still susceptible to power surges and fire risks. Safety systems must be in place and kept up, including sprinkler systems and emergency exit signs, to reduce injury risks to tenants and property loss.

The lightning rod, while useful, is antiquated compared to modern systems. As with the evolution of electricity in modern society, engineers learned much about lightning through the centuries, improving the capabilities of safety systems.

CTS and ESE Systems: The Modern Form of Protection

To prevent the adverse effects of what happens when lightning strikes a building, it is necessary to improve the protection zone of lightning rods. Two newer lightning protection systems can increase the area: CTS and ESE.

A charge transfer system uses four components: an ionizer, a ground current collector, a grounding system, and a grounding conductor. The conductor connects the ionizer to the grounding system. The entire system works by capitalizing on the point-discharge current phenomenon.

The CTS system reduces the electric field at and below the device, ensuring the discharge path for lightning is not preferable. If the electric field does provide a preferable route, the CTS system can collect the strikes from a larger area than a rod.

Alternatively, what happens when lightning strikes a building with an early streamer emitter air terminal? An ESE air terminal, like a lightning rod, is an arrester; however, the rod is inactive while the terminal is active.

The ESE system produces an artificial ascending channel to help disperse electricity surrounding the property. The system essentially creates a protective ionized dome around a structure, protecting integral components within a specific radius.

Why Lightning Protection Is Important to Property Owners

Damages and Costs

New York State receives approximately 3.8 lightning strikes per square mile annually, while the Empire State Building gets 25 strikes in the same timeframe. Because of the height of the NYC skyline, buildings are more prone to lightning strikes, and without the proper protection, buildings are susceptible to significant damage.

According to the Insurance Information Institute, lightning and fire account for roughly 35% of property losses. In 2018, lightning claims amounted to over $900,000,000 for 78,000 policyholders, nearly $12,000 per claim.

Financial, property and other losses from lightning strikes are preventable. With a sufficient system in place, it is possible to protect your property and tenants from fires, equipment damage, shock, and electrocution.

Protect Your Property Against What Happens When Lightning Strikes a Building

Hire Bolt Electric To Install a Protection System

Real estate portfolio owners might believe that what happens when lightning strikes a building is out of their hands. To the contrary, as an owner, you can purchase modern protection systems. Contact Bolt Electric at 212-434-0098 to discuss lightning protection systems and installation.