How do lightning conductors work

A metal rod placed on top of a building to protect it from a lightning strike is known as a lightning conductor. This conductor is struck first in lightning without hitting the building directly, preventing fire or electrocution.

It provides a harmless and easy path for the lightning energy to pass into the ground without damaging the structure of the buildings. The path or the earthing system is installed from the top to the bottom of the building. The conductor provides a poor resistance path between the top of the conductor rod through a substantial metal strip to the ground. Hence the current from the lightning strike is diverted through the rod and avoids flowing through the building. The lightning conductor works on the principle of induction.

When a fully charged cloud passes by the building, the conductor gets charged oppositely through the process of induction and this acquired charge moves to the earth through the earthing system. The electrical length of its rod will always be greater than its physical length.

The air becomes a conductor in the presence of a large electric field, and this electric field is strong around sharp objects than the objects where the surface is flatter.

During the build-up of lightning, charges are induced at the top of the pointed lightning conductor rod by the cloud charge. The effective length of the conducting path of the conductor is extended as the induced charge is sufficiently large and the air around the point of the lightning conductor. Recent lightning conductors are slightly rounded because the electric field created by a charged round point conductor is smaller when compared to a sharp point.

Hence, the air conducting cover a greater distance above the lightning conductor rod. The ionization of air around a lightning conductor rod then allowing the lightning to strike more randomly. This rod should be taller than the structure. If the area finds itself in a strong electric field, the tall rod can begin sending up positive streamers in an attempt to dissipate the electric field.

While it is not a given that the rod will always conduct the lightning discharged in the immediate area, it does have a better possibility than the structure. Again, the goal is to provide a low-resistance path to ground in an area that has the possibility to receive a strike.

This possibility arises from the strength of the electric field generated by the storm clouds. Ben Franklin was not struck by lightning. Contrary to popular school teachings, Mr. Franklin was very lucky to survive his experiment.

Franklin would surely have been killed. As we all know now, his experiment was extremely dangerous and should not be repeated. Sign up for our Newsletter!

Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. This creates an opposite charge on the Earth's surface. Buildings, trees and even people can experience a buildup of static charge as electrons are repelled by the cloud's bottom.

With the cloud polarized into opposites and with a positive charge induced upon Earth's surface, the stage is set for Act 2 in the drama of a lightning strike. As the static charge buildup in a storm cloud increases, the electric field surrounding the cloud becomes stronger. Normally, the air surrounding a cloud would be a good enough insulator to prevent a discharge of electrons to Earth. Yet, the strong electric fields surrounding a cloud are capable of ionizing the surrounding air and making it more conductive.

The ionization involves the shredding of electrons from the outer shells of gas molecules. The gas molecules that compose air are thus turned into a soup of positive ions and free electrons. The insulating air is transformed into a conductive plasma.

The ability of a storm cloud's electric fields to transform air into a conductor makes charge transfer in the form of a lightning bolt from the cloud to the ground or even to other clouds possible. A lightning bolt begins with the development of a step leader. Excess electrons on the bottom of the cloud begin a journey through the conducting air to the ground at speeds up to 60 miles per second.

These electrons follow zigzag paths towards the ground, branching at various locations. The variables that affect the details of the actual pathway are not well known.

It is believed that the presence of impurities or dust particles in various parts of the air might create regions between clouds and earth that are more conductive than other regions. As the step leader grows, it might be illuminated by the purplish glow that is characteristic of ionized air molecules. Nonetheless, the step leader is not the actual lightning strike; it merely provides the roadway between cloud and Earth along which the lightning bolt will eventually travel.

As the electrons of the step leader approach the Earth, there is an additional repulsion of electrons downward from Earth's surface. The quantity of positive charge residing on the Earth's surface becomes even greater.

This charge begins to migrate upward through buildings, trees and people into the air. This upward rising positive charge - known as a streamer - approaches the step leader in the air above the surface of the Earth. The streamer might meet the leader at an altitude equivalent to the length of a football field. Once contact is made between the streamer and the leader, a complete conducting pathway is mapped out and the lightning begins.

The contact point between ground charge and cloud charge rapidly ascends upward at speeds as high as 50 miles per second. As many as a billion trillion electrons can transverse this path in less than a millisecond. This initial strike is followed by several secondary strikes or charge surges in rapid succession.

These secondary surges are spaced apart so closely in time that may appear as a single strike. The enormous and rapid flow of charge along this pathway between the cloud and Earth heats the surrounding air, causing it to expand violently. The expansion of the air creates a shockwave that we observe as thunder. Tall buildings, farmhouses and other structures susceptible to lightning strikes are often equipped with lightning rods.

The attachment of a grounded lightning rod to a building is a protective measure that is taken to protect the building in the event of a lightning strike. The concept of a lightning rod was originally developed by Ben Franklin. Franklin proposed that lightning rods should consist of a pointed metal pole that extends upward above the building that it is intended to protect. Franklin suggested that a lightning rod protects a building by one of two methods. First, the rod serves to prevent a charged cloud from releasing a bolt of lightning.