lighting struck building

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mistabass

mistabass

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Rhode Island
I have a building that got hit by lighting it took out part of there phone system. nothing else checked visualy the ground have 4000 amp service 3/0 to bld. steel 3/0 to water service #6 to grd rod. data room has grd bar to bld. steel equipment tied to it just trying to figure out how stuff blew up . also the phone lines have isolator on both ends .
 
Number one reason is because lighting SAID SO. I am not being sarcastic.

WE have a tower site that has some of the most elaborate grounding I have seen, multiple level TVSS, chemical grounds, tons of copper. This site has been hit numerous times and fried everything, left burn marks on the interior, at everyplace a plastic stand-off held a bare ground conductor took out a cable TV site next door, damaged all electronics in 3 houses, a gas station and 7-11.

The point is you cannot protect against every lighting strike. Depends on the magnitude and duration of the strike, where it hits, what is most susceptible and other factors Mother nature can through at you.
 
just thought it was odd it only took out some parts of the phone system.the data room is on ground floor of 3 story bld .and didn't effect anything else
 
for buildings that are not more than 2 or 3 stories, aeirial grounding rings are highly effective (although not very attractive)
 
nakulak said:
for buildings that are not more than 2 or 3 stories, aeirial grounding rings are highly effective (although not very attractive)
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As it was posted earlier there is no absolute protection against lighting. The maximum protection is accomplished by a complete Faraday cage.

As controversial it is the LEC protection had performed flawlessly over one of our large plant for several consecutive years now. Saved us multi-millions in outages. The majority of the technical community is RABIDLY opposed to it, just beacuse they can not explain why it works. Even when you are an engineer or a scientist - or maybe BECAUSE you are one - you should recognize that not everything is or can be understood at this point in scientific knowledge. That system, wisely, does not claim absolute protection either.
 
I said highly effective, I didn't mean anything more. The navy has been using this at many facilities for many years with good results. Of course, it is only the first layer of "protection" against direct strikes. secondary grounding rings and mats help, as well as substantive building construction methods. I agree with you, though, that there is no absolute protection, and I also agree that even if you are able to redirect the direct strikes, it does not mean that your wiring and communications will not be subject to being fried from errant surges (regardless of the lengths taken to provide surge protection)
 
weressl said:
As it was posted earlier there is no absolute protection against lighting. The maximum protection is accomplished by a complete Faraday cage.
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Is that the "Umbrella" like stucture that I have seen on some smokestakes and cell towers? I've heard that it works by repelling, or dissipating the lightning charge.
 
Lightning can do strange things. We had a chicken farm near here, with the main service on a pole located between the dwelling house, and a chicken house.

Lightning struck that pole, came into the dwelling house on one of the hot lines, and blew up the main service panel right out of the wall! Set fire to the house, etc.

The chicken house was unfazed, its power never being interrupted! Both structures served from the same farmstead pole. Go figure. :-?
 
mistabass said:
I have a building that got hit by lighting it took out part of there phone system. nothing else checked visualy the ground have 4000 amp service 3/0 to bld. steel 3/0 to water service #6 to grd rod. data room has grd bar to bld. steel equipment tied to it just trying to figure out how stuff blew up . also the phone lines have isolator on both ends .
Click to expand...

In a basic explanation, it is because there are so many variables in a lightning strike, one of the biggest is the now known high frequency component of the stroke, if you know anything about high frequency RF energy, it takes a receiving antenna tuned to the correct resonate wave length or a divisional there of, for the transmitted signal to excite the electrons in the antenna for the receiver to receive the signal, other signals of different frequency's just pass by and can't even see the antenna. this is light lightning, lightning will take the path of a item that has the resonate wave length at the time of the strike, this might be a phone line one time or a cable line, or even a fence line. but it all depends upon the resonate frequency at the time of the stroke, and this is the variable that changes in each stroke, this is because of many things, like how much distance the lightning must travel, as it can be generated in low clouds or high clouds, there is also the capacitance of the air that also contribute to this, as well as many more things. but one thing for sure, it will strike the point that is in it's window of the resonate wave length. I have seen lightning ignore a 300' tower with all kinds of ground rings and 50' rods through the ground plane for an AM transmitter tower and hit a small 15' tree not 50' away from these towers, that was because it couldn't see the towers, but the tree that has branches of many varying different lengths acts like a broadband antenna, this is why trees are hit more then anything else on earth except maybe mountains.

Hope this can help with the "why lightning can hit one thing but leave somthing that seems more likely a target totaly alone.;)
 
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