Wednesday 14 March 2012

The Origins of Lightning Protection

Lightning protection science was first conceived by Benjamin Franklin in 1749 with his invention of the first pointed lightning rod conductor that became known as a “lightning attractor” and much later  as the “Franklin Rod.” Franklin spent many years in the lightning protection design process to include his famous kite experiment, which took place as he was waiting for permission to test his theories on the new Christ Church structure in Philadelphia, PA. Although Franklin did not patent any of his inventions, he published advice on lightning protection in Poor Richard's Almanac in 1753.
At that time, common belief was that lightning was a creation of God and therefore should not be interfered with in anyway. Franklin was finally able to convince the church deacons that they should take precautions against lightning damage by installing the lightning protection he designed, citing that rain was also a creation of God but roofs were still used on buildings to protect people and contents of buildings.
During the 19th century, lightning protection became an architectural addition to many public and private structures. The overall pointed rod design was complimented with ornamental solid glass balls, which were not only decorative but were believed to be an integral element in the effectiveness of the lightning protection of the structure. The theory behind this addition was that since glass is a non-conductor of electricity that they would repel the charge and for a time, because of the erratic behaviour of lightning it was believed this was scientifically proven.
Both the pointed design and the addition of the solid glass balls were soon proven by Nicola Tesla to be a flawed lightning protection design. Tesla's patented design was a great improvement over Franklin's original lightning protection of the pointed rod. In 1919, years after receiving his patent, Tesla publish an article, “Famous Scientific Illusions” in The Electrical Experimenter explaining the logic he used to dispel the science of Franklin's pointed lightning rod and scientific knowledge he used to design his lightning protection device. In his article, Tesla proved that the pointed tip of the iron rod actually ionised the air around it, which rendered it air conductive and raised the probability of a lightning strike.

Over the decades, since Franklin and Tesla, there has been much progress in lightning protection systems. Great innovations in design and methodology have advanced the protection of mission critical systems for military and government operations and commercial applications. From transportation system control centres to mobile phone transmission towers, the instances of catastrophic damage to these and other services we had all come to take for granted has been greatly reduced.