[TowerTalk] Fwd: Fwd: Fwd: The Need for Grounding

[Hans Hammarquist]

kelly,


I don't really understand your question. "boundless"? I, myself, was more into overdoing it rather than underdoing it and later found out "it was to little. I have 9 grounding rods around my tower. Three conductors, one to each rod, will also have lower inductance than only one conductor.


My shack is also shielded by and this shield is connected to the tower with a 6 inch wide aluminum band. My idea is that at a lightning strike in the tower (or anywhere else that affect the installation), the voltage difference between the tower and the shack is minimized and thereby limiting damages inside the shack.


It might be possible that one grounding rod is OK but I will not take that chance. If you, on top of that believe that a grounding rod can be "overloaded" you will use more than one.


I still don't know is a layer of glass can form around a rod in case of "overload". Anybody knows?


Hans - N2JFS



-----Original Message-----
From: Kelly Taylor <ve4xt at mymts.net>
To: Hans Hammarquist <hanslg at aol.com>
Sent: Thu, Jan 14, 2016 2:20 pm
Subject: Re: [TowerTalk] Fwd:  Fwd:  The Need for Grounding

Hi Hans,

If the capacity of a single rod was boundless, there wouldn't be a need for more than one, yes?

73, Kelly
ve4xt

Sent from my iPhone

> On Jan 14, 2016, at 1:13 PM, Hans Hammarquist via TowerTalk <towertalk at contesting.com> wrote:
> 
> 
> 
> No, the current does not follow "the shortest path". Yes, my mother always said that but Ohms' law predict more accurately how the current divide. More current will go through a lower resistant/ high conductive path but there will be current going through any conductive path, high or low.
> 
> 
> Keep in mind that due to ionization conductivity can change during a lightning event. The current will even follow paths generated directly through air. I guess you might also experience where grounding rods get insulated from ground due to the glazing effect due to the very high current density and following high temperature. I don't know if this ever happens but like to hear if anybody knows.
> 
> 
> All the above events will lead to the unpredictable path of lightning damages.
> 
> 
> An other phenomena you might encounter is, if you are present at the lightning event, that the lightning flashes seen, do not necessary occur at that point the observer claim they saw them. This is something I experienced my self.
> 
> 
> Best 73 de,
> 
> 
> Hans - N2JFS
> 
> 
> 
> 
> 
> -----Original Message-----
> From: Kelly Taylor <ve4xt at mymts.net>
> To: Edward McCann <edwmccann at yahoo.com>
> Cc: Bryan Swadener via TowerTalk <towertalk at contesting.com>; Hans Hammarquist <hanslg at aol.com>
> Sent: Thu, Jan 14, 2016 12:24 pm
> Subject: Re: [TowerTalk] Fwd:  The Need for Grounding
> 
> The important thing to remember is electricity doesn’t follow the shortest path somewhere, it follows the path of least resistance. And it’s important to point out that during a lightning event, that path is going to change, as the lightning charge will easily overload a single rod, driving that rod’s resistance sky high. Since the event is not yet over, the remaining charge will follow the next-best path, which could be through your radio. Better it be through the other rods in your network, no?Is it useful to envision ground rods as resistors, and a chain of ground rods as resistors in parallel?Since we all know parallel resistors divide current among them, and as a group present a resistance that is some fraction of their individual values, is it a good meme to remind us of the importance of multiple rods?73, kellyve4xt> On Jan 14, 2016, at 10:35 AM, Edward McCann via TowerTalk <towertalk at contesting.com> wrote:> > On point.> It is unlikely Ohm's Law will ever be repealed,> by the current crew in the beltway or that if the pretenders to the throne.> AG6CX> > Sent from my iPhone> >> On Jan 14, 2016, at 8:22 AM, Hans Hammarquist via TowerTalk <towertalk at contesting.com> wrote:>> >> It's simply Ohm's law that still is valid. Yes, voltage across all the inductance adds in too.>> >> >> In my case, my tower is grounded with a resistance to ground of about 3 ohms (when it was tested some time ago). If the tower is hit, (I guess) the current is about 3 kA with a resulting 9 kV between the tower and ground. 
> 
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