Lightning Strikes and Power Surges

Flash! Flash! Flash! BANG! Its a lightning storm. The long, cold, pipe-breaking winter season is finally over. Welcome to lightning season!

For more than 6 months a year an adjusters in-tray is often flooded with alleged lightning claims. The question is: Are they all really lightning claims?

To answer that question it is necessary to find out what lightning is all about and how it inflicts damages on electrical equipment.

Lightning is a simple phenomenon of static electricity discharge. When clouds roll through the atmosphere they often accumulate a large amount of static electricity. When the accumulation is sufficiently high and when conditions are right, discharge will occur. Sometimes the clouds will discharge against the ground and sometimes they will discharge against other clouds. This discharging of electricity, often associated with the emission of light and sound, is what is commonly known as lightning.

On a dry day when you touch a light switch or something metallic after walking on nylon carpet you often get a tingle and see a little spark jump between your fingertip and the light switch. This is a miniature version of a lightning strike. Much like a cloud accumulating electricity and discharging it against the ground, your body accumulates the electricity and then discharges it. It discharges against the light switch or the object that you touched. The tiny spark is the lightning bolt and the faint cracking sound is the thunder.

Typically in two ways - direct strike and induction.

Direct strike happens when the static electricity is directly discharged onto an object. Just think of it as a waterfall from the sky  electricity in the cloud is like the water above the fall and the ground is like the water at the bottom. The affected object is like a little pile of rocks that the water hits. When the water reaches the rock pile below, it makes a significant impact and travels through the space in between the rocks and finds the shortest path to the lower level. A large amount of energy has been released and everything in its way will either be shaken or pushed away.

In a direct lightning strike the situation is remarkably similar. When it hits, the discharged electricity has to find the shortest path to the ground. Anything in its way can be destroyed or damaged by the huge release of energy. You can always tell whether it was a direct strike by looking for burn marks, molten wires, overheated components and the like. These are all evidence of energy dissipation.

Induction is something entirely different. Lets go back to the waterfall example: If you stand too close to the falling water you will feel the vibration and your hearing will be momentary impaired by the deafening noise. You do not have to be in physical contact with the water but you are still affected by the release of its energy, in this case the sound and the vibration energy.

In a lightning strike the situation is very similar. In addition to electricity, a lightning bolt also releases electromagnetic energy in the form of intense radio waves. These waves travel for miles in all directions from the strike zone and can be picked up by anything that resembles a radio antenna. Anything connected to such an antenna will be affected.

It is much harder to tell whether damage was caused by induction since it seldom leaves burn marks. This is because the energy involved is much less than that released by a direct strike. You must establish what has acted as an antenna and picked up the energy when lightning struck some distance away. Was it the TV antenna on the roof? Was it the overhead power lines outside? Was it the phone lines? Was it the computer networking cables? Anything over 20 feet long is a suspect.

The second thing to look for is what items were connected to the antenna. Were they damaged? What kind of damage? How severe was the damage? If you plot the locations and the connections of all the damaged equipment and components do they form a certain pattern? All of these clues will help to determine whether lightning was actually involved.

If in doubt perhaps some expert advice from an electrical engineer who understands lightning would be helpful.