According to scientists’ calculations, at any given moment, there are approximately 2,000 thunderstorms occurring on our planet. Each thunderstorm typically lasts between 2 to 4 hours and can produce between 1,000 to 2,000 lightning strikes to the ground.
Thunderstorms have been likened to power plants with a capacity of several hundred megawatts, with voltages reaching up to billions of volts. The electric power from a single lightning strike can illuminate a 100W light bulb for three months. With such intensity, thunderstorms pose significant dangers to human life and can cause substantial material damage.
In 1769, when humanity was unaware of lightning protection devices as we know them today, a disaster occurred when lightning struck a storage facility of over 1,000 tons of explosives in an Italian city. The entire building exploded, killing more than 3,000 residents. Following the invention of the lightning rod by scientist Benjamin Franklin, such devastating losses from lightning strikes no longer occurred. Since then, although we have not completely eliminated the risks, lightning protection devices have significantly reduced the damage caused by lightning, thus protecting human lives. Over the past 200 years since the first lightning rod was introduced, lightning protection technology has continuously improved and become more effective.
In 2001, Vietnam’s electricity sector recorded around 400 incidents, with 50% of them caused by lightning. Notably, on June 4, 2001, lightning struck a 220 kV circuit breaker at the Hoa Binh Hydropower Plant, causing a blackout in northern Vietnam and disconnecting numerous power plants from the grid. Hanoi and several other provinces experienced widespread power outages.
What is the nature of thunder, lightning, and electrical discharges?
During thunderstorms, strong winds stir up clouds, causing them to become electrically charged. When two oppositely charged clouds come close to each other, the voltage between them can reach millions of volts. An electrical discharge occurs between the two clouds, resulting in a visible flash of lightning. A few seconds later, we hear the sound of thunder, which occurs because light travels faster than sound (hence we see the lightning before hearing the thunder). If an electrically charged cloud approaches the ground in open areas and encounters a tall object such as trees or a person holding a metal tool, an electrical discharge occurs between the cloud and the ground, resulting in a lightning strike.
The most effective way to protect against lightning is to install lightning rods. Skyscrapers must have lightning rods.
The structural principle of a lightning rod is quite simple: a pointed metal rod is mounted on the roof of a building, directed skyward. A grounding wire (typically 0.04 mm iron) is welded to the bottom of the rod, leading down to moist ground and buried deeply. For larger buildings, multiple lightning rods may be required, and their grounding wires should be interconnected.
In open areas prone to lightning strikes, lightning rods should be installed. A wooden or concrete pole about 5 to 6 meters tall is used, with a pointed metal rod welded at the top. The tail of the metal rod is connected to a grounding wire (also using 0.04 mm iron). Theoretically, a lightning rod can protect a conical space with a base radius equal to the height of the pole. In areas with frequent lightning, a system of lightning rods should be installed, spaced about 20 to 30 meters apart. The grounding wires should be interconnected and buried deeply.
When a thunderstorm is approaching, it is advisable to return home quickly and avoid seeking shelter under large trees or in high-risk areas for lightning strikes. It is also wise to refrain from unnecessary outdoor activities. Circuit breakers should be turned off, as lightning can travel along power lines into homes. Additionally, remove any antennas from radios to prevent damage from lightning strikes and protect those nearby.
