Lightning Strike Information

Posted 2024-04-13 22:46:19

Lightning strikes are a powerful natural phenomenon that can pose risks to electronic and digital equipment. Understanding the amperage and voltage levels of lightning strikes and their impact on equipment is crucial for protection. In this article, we will delve into the details of lightning strikes and provide answers to frequently asked questions.

Typical Amperage and Voltage Levels

Lightning bolts can range from 5,000 Amperes to 200,000 Amperes, with voltages varying from 40,000 Volts to 120,000 Volts. The amperage and voltage levels determine whether electronic or digital equipment will be damaged when struck by lightning. The vulnerability of the equipment depends on what it is attached to and the level of amperage and voltage during the strike.

Safe Distance from a Lightning Strike

The safety of electronic and digital equipment during a lightning strike depends on the voltage level at the strike point. The voltage and current from a lightning strike races across the earth in all directions, dissipating until it reaches zero voltage. Therefore, electronic and digital equipment are not completely safe until the facility reaches a zero-earth voltage level. The distance required for the voltage to reach zero varies depending on the resistance of the soil, which could take up to nine miles in all directions.

Travel of Lightning Voltages Across the Earth

Lightning voltages seek their own voltage return path until they reach zero volts. These voltages can travel on all conductive paths, including metallic pipes, underground wires, and other metallic objects. These paths usually have lower resistance values than the soil, so a significant amount of voltage and current will flow through them. This phenomenon is known as Ground Potential Rise or Earth Potential Rise. As facilities require grounding, the lightning voltage and amperage can directly affect electrical equipment via the grounding systems, potentially causing equipment failure.

Lightning Strikes and Storm Fronts

Typical lightning strikes can occur 5-10 miles ahead of a storm front. Anvil lightning, also known as "lightning from out of the blue," can strike hundreds of miles ahead of the storm front.

Visibility of Storm Fronts

For an average person with an eye level of 5 feet 7 inches, the horizon is visible at a distance of 2.9 miles. If standing on a 100-foot hill, the horizon extends to a distance of 12.2 miles.

Protection from Ground Potential Rise

To protect electrical equipment from ground potential rise, proper grounding and surge protection must be in place. This includes installing surge protection for AC service, telephone lines, data lines, coaxial cables, CCTV, CATV, antenna systems, and radio systems. Additionally, all ground loops for voltage-susceptible equipment must be eliminated.

Building and Electrical Equipment Protection from Lightning Strikes

In addition to protection against ground potential rise, a properly installed Lightning Protection System (LPS) is essential for protecting buildings and electrical equipment from lightning strikes.

Risks from Lightning Strikes

The risks from lightning strikes can vary, depending on whether a person is inside or outside the home. Inside the home, risks include contact with metallic objects, talking on a telephone land line, contact with water, and side flash from a metallic-lined chimney. Outside the home, risks include direct strikes, side flash from a nearby lightning strike, ground potential rise from a nearby lightning strike, contact with metallic objects, contact with water, and being in an open field during a lightning storm.

Facility's Risk from Lightning Strikes

The risks faced by a facility from lightning strikes can be determined by the average number of lightning strikes per year by state. However, it is important to note that the average strikes per square mile do not necessarily represent the state with the most lightning strikes.

To protect against lightning strikes, facilities should invest in proper lightning protection systems and take necessary precautions to ensure the safety of their electronic and digital equipment.

Frequently Asked Questions

Q: What is the typical amperage and voltage levels in a cloud to earth lightning strike?
A: Lightning bolts range from 5,000 Amperes to 200,000 Amperes, and voltages vary from 40,000 Volts to 120,000 Volts.

Q: How far away from a lightning strike is your electronic and digital equipment safe?
A: Electronic and digital equipment are not 100% safe until the facility reaches a zero-earth voltage level, which could take up to nine miles in all directions.

Q: What happens when lightning voltages travel across the earth?
A: Lightning voltages travel across the earth in all directions, seeking their own voltage return path until they reach zero volts. They can travel on all conductive paths, such as metallic pipes and underground wires.

Q: How far in advance of a storm front can lightning strike?
A: Typical lightning can strike 5-10 miles ahead of a storm front, while anvil lightning can strike hundreds of miles ahead.

Q: How far away can a person see a typical storm front?
A: For an average person with an eye level of 5 feet 7 inches, the horizon is visible at a distance of 2.9 miles. On a 100-foot hill, the horizon is visible at a distance of 12.2 miles.

Q: How can electrical equipment be protected from ground potential rise?
A: Proper grounding, surge protection, and elimination of ground loops for voltage-susceptible equipment are essential for protecting against ground potential rise.

Q: How can my building and electrical equipment be protected from a lightning strike?
A: A properly installed Lightning Protection System (LPS) should be installed in addition to protection against ground potential rise.

Q: What are the main risks from a lightning strike?
A: Inside the home, risks include contact with metallic objects, talking on a telephone land line, contact with water, and side flash from a metallic-lined chimney. Outside the home, risks include direct strikes, side flash from a nearby lightning strike, ground potential rise from a nearby lightning strike, contact with metallic objects, contact with water, and being in an open field during a lightning storm.

Q: What is my facility's risk from a lightning strike?
A: The average number of lightning strikes per year by state varies. Please refer to the provided table for a breakdown of lightning strikes per state.

In conclusion, understanding the nature of lightning strikes and taking appropriate measures to protect electronic and digital equipment is crucial. By implementing proper grounding, surge protection, and lightning protection systems, the risks associated with lightning strikes can be significantly reduced.

Lights

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