I saw he put a grounding line on the thing, and a ground rod. But Something that tall and close to an inhabited structure should really have a heavier line that goes right to the top. Lightning will fry that #6 conductor pretty fast, and then where will it want to run? Oh, by the way, he has thoughtfully provided a fortuitous conductor that leads directly into his computer! Two words, " lightning arrestor " And I wasn't too thrilled with his weld quality either. Looks like it was showing rust in the pic
Lighting rods don't necessarily conduct all of the lightning's current. One idea is that they conduct some current and ionize the air around them -- then the bulk of the current flows through that ionized air (just like the ionized air lightning usually flows through). Another theory is that they work to prevent lightning. [duke.edu] This is one of those things that has led to much debate [straightdope.com].
Bullcrap. This gets a lot of edit time on the Lightning rod wikipedia page without any reasonable justification. I did the calculations on the talk pages a while back: http://en.wikipedia.org/wiki/Talk:Lightning_rod [wikipedia.org]
The lightning page states that each discharge produces 30kA. The conductor proposed (.25inch*.25inch*pi = 126mm^2) has a resistance of 1.6mR cm * 1m/126mm^2 = 0.13mR/m, each m weighs 126*9g = 1.14kg giving a heat capacity of 438 J/K per metre. Each m will drop 3V, i.e. 90kW of power. The flash l
I liked your post, but I have no idea why you say "bullcrap". You're saying that a 1/2" diameter wire would only rise 20 degrees K, so it wouldn't be damaged. Nice work - I agree. But then you say that the conductor is probably only 1/1000th the resistance... I'm not sure what that means -- you must be talking about a parallel path because the current would be the same through a series path. 1/1000th the resistance contradicts your next statement -- lower resistance would take the majority of the power, so
I think he's referring to the fact that most of the energy is dissipated earlier, as the lightning strike is travelling through the ionized air. The "high resistance" portion of the journey. High resistance means high power/heat dissipation. Since the tower is in relative terms extremely low resistance, it would not be dissipating nearly as much power.
The bullcrap was about lightning prevention (sorry, I should have made that clear) and that the conductor isn't rated to survive a lightning hit. Parallel path seems very unlikely considering the available conductor density. If there were a parallel discharge one would expect melting or charring around conductors, either of which I've not seen. The resistance of the lightning rod might be 1000th the resistance of the whole strike (from cloud to ground), so although a lightning bolt has a high power, most o
All I can say about the bull crap part is that before I errected my tower we had hits close enough to my poll pig
to trip the protector nearly each summer at least once.
Since putting the tower in place about ten years ago, not once has the pig been hit. Only once has anything happened close enough to the tower to cause any damage of my equipment (lucky?). I do have each leg directly grounded with it's own #4 wire and 8 foot ground rod.
Another ham down by the river where the storms rush by has his 200' t
Lightning protection (Score:5, Interesting)
And I wasn't too thrilled with his weld quality either. Looks like it was showing rust in the pic
Re:Lightning protection (Score:2)
Re:Lightning protection (Score:2)
http://en.wikipedia.org/wiki/Talk:Lightning_rod [wikipedia.org]
The lightning page states that each discharge produces 30kA. The conductor proposed (.25inch*.25inch*pi = 126mm^2) has a resistance of 1.6mR cm * 1m/126mm^2 = 0.13mR/m, each m weighs 126*9g = 1.14kg giving a heat capacity of 438 J/K per metre. Each m will drop 3V, i.e. 90kW of power. The flash l
Re:Lightning protection (Score:1)
Re:Lightning protection (Score:2)
I could be wrong, though.
Re:Lightning protection (Score:2)
The resistance of the lightning rod might be 1000th the resistance of the whole strike (from cloud to ground), so although a lightning bolt has a high power, most o
Re:Lightning protection (Score:2)
ps. I'm so full of crap, you could have been responding to any one of a number of things!
Re:Lightning protection (Score:2)
LIghtning dissipation (Score:1)
Since putting the tower in place about ten years ago, not once has the pig been hit. Only once has anything happened close enough to the tower to cause any damage of my equipment (lucky?). I do have each leg directly grounded with it's own #4 wire and 8 foot ground rod.
Another ham down by the river where the storms rush by has his 200' t
Re:LIghtning dissipation (Score:2)