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A previous discussion between engineers about earthing was
in two discussions in the newsgroup misc.rural entitled: Storm and Lightning damage in the country 28 Jul 2002 Lightning Nightmares!! 10 Aug 2002 http://tinyurl.com/ghgv and http://tinyurl.com/ghgm If your building does not, at minimum, meet post 1990 National Electrical Code (NEC) requirements, then sufficient earthing may exist. Connection to cold water pipe is no longer sufficient to earth for human safety reasons. Earthing for transistor safety typically exceeds what the NEC requires. Distance to that earth ground is critical. Plug-in 'shunt mode' protectors are too far from earth ground; not sufficiently earthed to provide secondary protection. Therefore those ineffective (and so grossly undersized) protectors avoid all discussion about earthing. Earthing a building is for secondary protection. Also inspect earthing for your primary protection: http://www.tvtower.com/fpl.html Ham radio operators would disconnect the antenna, place the antenna lead inside a mason jar, and still suffer damage. Disconnecting alone was not sufficient protection. Damage stopped when the antenna lead was earthed. Do as Ben Franklin demonstrated in 1752. Give the surge a non-destructive path to earth. Lightning rods and 'whole house' protector; both do same. Earth before lightning can enter a building. finalquest wrote: w_tom - I do believe you make a very valid and important point. After reading up on it a bit, one point grounding is one of the most important things that need to be checked. As you mentioned the cheaper surge protectors need that good ground to work properly. I'm still researching this and have to agree at this point, the best protection is to disconnect everything but there are times that's not practical. Once again, THANKS to everybody that's helping out. |
tvtower.fpl.html That guy sure got that right about Bell South,and how!
Last year,starting the first night of November on through about half of December,my phone line would quit working every single time it rained here and by the time I got my phone line repaired,it had rained over fourteen seperate times here.I phoned them two times and still didn't get my outside phone line repaired.I phoned them a third time and a Bell South repairman guy disconnected a wire inside my phone box inside my carport.My house has a crawlspace under it high enough I can sit up under there and my own phone wires are always dry under there where they are fastened to the floor rafters/boards.It never rains on that box which is mounted about three feet high on a wooden baseboard above the concrete foundation of my house,the phone box is always high and dry.The wire he disconnected is a wire from their end of the phone wires up there on that pole at the end of my driveway by the road.Bell South,(RIPP OFF! Bell South!) wanted to charge me $101.50 for something that had nothing to do at all with the phone wires from my end of my phone line wires to their phone box.You have to always be on your toes and watch out! about those utility Crooks! cuhulin |
Ham radio operators would disconnect the antenna, place the
antenna lead inside a mason jar, and still suffer damage. Only dumbass hams, and some CBers did that stunt. About a stupid trick...Like a little glass bottle is going to stunt a strike that traveled a few miles in *air* to get there... When I ground out my feedlines, it's to a good ground, and is totally outside. When I take a strike, or even a close non direct strike, you can hear those feed to ground connections arc, even though they are connected by so-239's/pl-259's. I've never had any trouble using that method, and I've had two direct strikes to my mast in the last 4-5 years. My mast directs most of the energy to ground, but you still have some current on the lines that needs to be cleaned up. You sure don't want to run it into the house... :( If the coax is elevated, and not snubbed to ground at any point, the strike potential at the end of the feedline will be *HUGE*. Disaster city... That much potential can travel halfway across a house looking for ground. Usually will seek plumbing, toilets, etc. I've heard of toilets being blown to bits in a case like that. MK |
Welll.....Sorta... To me, it's almost in both directions at the same
time it's so quick. I guess you could consider the streamer as the first part of the strike, but you need a down leader to complete the strike. The downleader connects with the streamer, and you have a strike, which can pulse more than once. If you have a streamer, and no leaders find it, you ain't gonna have a strike. So it takes both ends to make a strike. Saying it starts at the bottom is semi misleading, to me anyway...It really goes both ways, and they meet in the middle to complete a strike. Or thats the way I see it... But, the streamer does form first of the two, so I guess that would make it seem to start at the bottom... MK |
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finalquest wrote:
w_tom - I do believe you make a very valid and important point. After reading up on it a bit, one point grounding is one of the most important things that need to be checked. As you mentioned the cheaper surge protectors need that good ground to work properly. I'm still researching this and have to agree at this point, the best protection is to disconnect everything but there are times that's not practical. Once again, THANKS to everybody that's helping out. Indeed w_tom makes the best point about protection -- only a single point ground for ALL points in a system in which all are tied together and utilize a single point for a collective ground is effective. Damage is (and will) be done if there is ANY means for a potential to vary in a system. In other words, ALL points must rise and fall at the same time. Current flows when there is a difference in two points in a system. My radio tower is 65' high and located in west central Florida, aka Lightning Capital of the US. After a strike to the foundation of my home 3 years ago, which literally blew ceramic tiles off the concrete slab and turned them to shattered glass shards, and blew a 3 inch deep, 2 inch wide chasm some 5 feet long into the concrete, I undertook to make certain I was safer. The strike did not hit my tower...it actually struck the telephone equipment point 90 away in the front of my home. The measures I took are on my web page: http://www.knology.net/~res0958z/ Bill KC9CS |
"m II" wrote in message news:HpgIe.126039$wr.91437@clgrps12... magnetic mike II AKA the "Man of Steel"? |
Nice web page you have there,very informative too.
cuhulin |
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