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Re: A little off-topic - Lightning and Electrical Components
An old saying in the ham radio community is "the only thing predictable about lightning is it is unpredictable". While broadcast stations with tall towers do have protection to try and prevent damage that doesn't always work. Lightning has a few particular issues that make damage control difficult. We are talking kiloamps with rise times in the few microseconds and millions of volts. Mechanical devices like breakers and fuses will not respond to that kind event. Should a strike occur near your device, the resulting pulse can jump across the protecting device and still take out a lot of stuff. The pictures above are nothing, they were likely caused by a component failure or power supply fault. A lightning strike would have left a burned hole in the board.
Remember Ohm's Law. Calculate out the voltage developed across one ohm at 40,000 amps. So a bolt strikes your phone line in the backyard, roars up the line to your house and the first thing it encounters is a lighting block that has one side tied to a #10 wire that ties to you cold water supply pipe. The #10 is .001 ohms per foot and is ten feet long, the copper supply pipe is .0001 ohms per foot and is 20 feet long before it touches earth outside your house and then it reaches dry ground. Assuming that the arrestor doesn't disintegrate and ignoring that the water in the pipe turns to steam instantaneously and that the #10 wire doesn't vaporize, several thousand volts will be developed across the wire and pipe. Once outside, the ground dissipates the current but there will be a potential spread across your front lawn. If you are standing out there with your legs spread out, there could be a difference in potential between your two feet of several thousand volts.
I have seen lightning bypass the protectors and travel on the outside of a coaxial line and then jump into a transmitter and take out the final amp. I have seen lightning come down a tower that is grounded, jump six feet to a house, strike the water pipes and blow all the fixtures in the house as the water turns to steam at high pressure. I have been asked to repair TVs, computers, and VCRs that were taken out in a nearby strike. Some only needed a fuse, others, there was nothing left of the boards near the power cord. Just charred circuits and a lot of residue on the case where the components that blew up were left. Even on Sears, when it gets struck by lightning (several times a year, 50-100) the current travels through the building, down the 120 stories to the ground and then presumably to the Chicago River a half block away. If you look at the video I linked a few weeks ago, the lightning protection is not visible because the entire structure is the protection. Everything you see is bonded to building steel.
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Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
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Storming the Tower since 1996.
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