How Does a Lightning Rod Work?

Brief History

The lightning rod was actually invented over two-hundred years ago in 1749 by Benjamin Franklin in his process of attempting to explain exactly how lightning worked. He speculated that if a large iron pole with a sharpened tip were placed higher than other conductors in the area, the energy would first be attracted to it and be harmlessly diverted to ground. This is why lightning rods are sometimes referred to as "Franklin Rods". Flying a kite with a key attached to it was another test he used when studying how lightning works.

Material Used

Lightning rods use highly conductive metals that will attract and carry current better than surrounding objects such as buildings or trees. Although wood and other materials will conduct electricity of the charge is great enough, lightning will take the easiest path to ground, and sometimes will channel through trees, buildings or even people. Things such as plastics and glass will not conduct electricity until the atmospheric charge is extremely high, and therefore are not sufficient to use as an effective diversion.

How They Work

When electrical charges build up in the atmosphere, they eventually need a path to break down and release, and many times this will cause lightning to strike tall objects that can be substantially damaged. The purpose of a lightning rod is to intercept this electrical charge and channel it safely, and to prevent lightning from striking things that can catch fire or create unsafe conditions. The idea is to place the metal rod high enough so that electrical charges from the atmosphere will have a better chance of channeling through it instead of houses, trees, or people. If the electrical charge is allowed to build up substantially, it will eventually discharge through whatever object is nearest to the outlet.

Fun Fact

In the 1800s, the captains of large wooden ships would place pure glass balls at the top of the highest mast in order to prevent lightning from striking the vessel. The theory was that since glass was never struck by lightning, and was a horrible conductor of electricity, the ship would be safer from lightning strikes than if it had no glass ball. Of course, we now know that the idea was very flawed, and ships were still regularly hit by electrical storms regardless of the presence of these balls. Had they known how lightning rods worked, it is possible that several of the ships destroyed by lightning strikes would have sailed safely to their destinations!