If you built a barn or home during the past century, you were sure to include lightning rods on the roof as part of the structure. This simple method of protecting your property from a bolt of fire from the sky was considered good insurance. It is estimated by the National Lightning Safety Institute that one in 200 homes will be hit by lightning per year. WeatherStem reports that “about 100 lightning bolts strike the Earth’s surface every second. That’s about 8 million per day and 3 billion each year.”
It wasn’t so long ago that the character of a lightning bolt was unknown until Benjamin Franklin proved that lightning was a form of electrical energy with his kite and key experiment. He observed that lightning was “similar to electricity by the color of the light, its crooked direction, and the crackling noise it made.”
He went on to note, “may not the knowledge of this power of points be of use to mankind, in preserving houses, churches, ships, etc., from the stroke of lightning, by directing us to fix, on the highest parts of those edifices, upright rods of iron made sharp as a needle. Would not these pointed rods probably draw the electrical fire silently out of a cloud before it came nigh enough to strike, and thereby secure us from that most sudden and terrible mischief.”
Franklin proposed the principle for the use of lightning rods in 1749, but it wasn’t until 1760 that his discoveries were manifested in the protection of homes and other buildings in a practical way.
A lightning rod, also known as lightning conductors, finials, air terminals or strike termination devices, is usually made of conducting materials such as aluminum or copper; copper being the most commonly used conductor of electricity. If a thunderstorm was in the area, the pointed rod would, in theory, discharge some of the electrons in the clouds above, conducting them to the ground through a copper wire, thereby preventing a strike through the building, causing a fire or personal harm. Also, if a strike should occur, the rod would be hit first, and again, conduct the electrical charge harmlessly into the earth. A lightning bolt can heat the surrounding air to over 50,000 degrees, five times hotter than the surface of the sun. And, yes, lightning can strike the same place more than once. The Empire State Building gets hit by lightning 25 to 100 times annually.
During the 20th century, lightning rods became a decorative item, being embellished with ornamental glass balls of variegated colors. These balls were purely ornamental.
Also known as a lightning attractor or Franklin Rod, they were a common sight in Sauk County until the past half-century or so, when they became mostly obsolete. However, tall city buildings are still outfitted with lightning rod protection.
Editor's note: This article was updated Jan. 10 to correct the purpose of the glass ball on lightning rods and remove an incorrect statement regarding the propensity of lightning to strike one building vs. another.