Facts and Myths about Lightning

Facts

* The purpose of lightning protection is NOT to stop the lightning from striking.
You can't do that.
Lightning Protection controls the PATH of the lightning after it hits.
Like it or not, that is about the best you can do.
It's not lightning that causes the damage, it's lightning going through places you don't want it to.

* At any instant, there are more than 2,000 thunderstorms taking place throughout the world.
These storms combine to produce about 100 lightning flashes per second, each one with a potential of up to a billion volts, currents ranging up to 200,000 amperes and temperatures of over 54,000 degrees Fahrenheit.

* Lightning likes land. According to images of data from NASA's Lightning Imaging Sensor (LIS) From December 1997 to January 1998, LIS saw that 90% of lightning was over land.

* Almost nothing can offer 100% protection from lightning strikes or damage - but it can be reduced by 95% or more with simple precautions and relatively inexpensive installation methods.

* One hundred million feet per second is the quickness of the lightning streak through the sky. No wonder the flash is difficult to watch from beginning to end; it starts and stops at almost the same time. Lightning travels 90,000 mi/sec (nearly 1/2 the speed of light), 100,000 times faster than sound and therein lies the reason thunder is heard after the flash is seen. The stroke, which is about two inches across and between 200 feet and 20 miles long, lasts but a microsecond.

Myths

* A lightning rod or grounded tower or high structure makes it more likely that lightning will strike.
Wrong - It will have little or no effect on how likely it is that it will strike in the immediate area, the important thing is it will be conducted directly to ground, without having to go through your inverter and computer first.

* Lightning always strikes the tallest object. Wrong - It can strike ANYPLACE it is more likely to hit the highest object, there is no guarantee.

* You should not touch metal objects if lightning is in the area. This is GOOFY, yet the myth has even been perpetuated on some of the National Weather Services web pages. If you seriously think that lightning is going to worry about a 3 foot golf club after tearing through a mile or more of air, you probably should not be playing golf. Their was also a recent news story about how an under-wire-bra had "attracted lightning" - not hardly.

* Lightning could be used as a power source. Not likely. Unless you can figure out some way to store up 100,000,000 volts in a few microseconds. Most of the energy in a strike is converted to heat, sound and light energy anyway, so there is not much left over.

Where Lightning Can Strike

As can be seen from the Image, Lightning can strike any place.

Obviously, some areas are much more active than others - in fact Florida is usually considered the "Lightning Capital" of the world - 2nd only perhaps to some areas of Australia.

This Image does not show the relative INTENSITY, so it can be a little misleading.

Although the Southwest does not rate that high in the NUMBER of strikes, some of the Largest Strikes ever Recorded are from that area due to the sometimes Violent Updrafts from the Super Heated Desert Floor.

What Causes Lightning ?

Lightning originates around 15,000 to 25,000 feet above sea level when raindrops are carried upward until some of them convert to ice. For reasons that are not widely agreed upon, a cloud-to-ground lightning flash originates in this mixed water and ice region. The charge then moves downward in 50-yard sections called step leaders. It keeps moving towards the ground in these steps and produces a channel along which charge is deposited. Eventually, it encourages something on the ground that is a good connection. The circuit is complete at that time, and the charge is lowered from cloud to ground. The flow of charge (current) produces a luminosity that is very much brighter than the part that came down. This entire event usually takes less than half a second.

What Kind of Damage can Lightning cause ?

* Most electrical and electronic damage in off grid and solar systems is NOT due to a direct hit. In fact, direct hits are rare. Most damage occurs from nearby hits, usually within a few hundred feet. A near-strike can induce thousands of volts onto the house wiring if not protected. In a ground hit, it can be also spread out and travel into buried conductors, such as pipes. Contary to popular assumption, the panels are usually grounded (sometimes more by accident than design). Also, the battery banks on most systems acts as a fairly good surge arrestor if you have good connections - but it may take out the controller on it's way. If the battery bank is not grounded, damage can be much more severe - it may then leap around all over trying to find a path to ground.

* Cloud-to-ground lightning can kill or injure people by direct or indirect means. The lightning current can branch off to a person from a tree, fence, pole, or other tall objects. In addition, flashes may conduct their current through the ground to a person after the flash strikes a nearby tree, antenna, or other tall objects. The current also may travel through power or telephone lines, or plumbing fixtures.

* Similarly, objects can be directly struck and this impact may result in an explosion, burn, or total destruction. Or, the damage may be indirect when the current passes through or near it. Sometimes, current may enter a building and transfer through wires or plumbing and damage everything in its path. Similarly, in urban areas, it may strike a pole or tree and the current then travels to several nearby houses and other structures and enter them through wiring or plumbing fixtures. In some cases lightning can strike the ground and travel up buried power lines for hundreds of yards.