[Elecraft] OT: Ground rods and concrete

[Doug Person]

Working on a fire line in a national forest I've seen 75 foot pine trees 
that had been completely exploded from a lightening strike. The sap 
reaches boiling point in an instant and burning parts of the tree gets 
distributed over the ground which leads to a fire crew being dispatched. 
Most wildland fires in these parts are due to lightening and ocurr 5-10 
times per year.

My own antenna system has never had a direct strike despite the high 
lightening activity here in the high Rockies (8200'+).  But several 
times surges have blown the fuses on my lightening protectors.  One near 
strike even got past that and destroyed my switch box - which was also 
fused.

K0DXV

On 4/18/2017 11:41 AM, Guy Olinger K2AV wrote:
> Part of the mental imaging problem here is that our brains, in their
> internal emotional response to orders of magnitude, simply cannot scale the
> destructive power in lightning. Lightning is quite capable of melting the
> leads to six properly done ground rods, AND at the same time blowing up a
> perfectly done to code concrete base with reinforcing rods.
>
> It just needs to be a big enough strike. I would guess (zero proof, just a
> nagging inclination) that the odds of this are considerably reduced by the
> presence of decently tall trees in the immediate vicinity (another loooong
> discussion).
>
> Anyone who has seen a lightning strike turn three or four cubic yards of
> ground dirt into glass in milliseconds, or seen a huge strike on a lake
> surface boil water within a 10 foot radius has a good gut based lightning
> strike power scaling device.
>
> Every now and then I will get on YouTube and watch the cellphone videos of
> the 2011 Japanese Tsunami to remind myself of the absolutely enormous
> kinetic energy in a twenty foot high wall of water moving at 20 miles per
> hour.
>
> Nature can completely blast any one of us to smithereens if it wants to.
> Thankfully that is nowhere near norm.
>
> The question is how much moolah do you want to lay down, how many otherwise
> good solutions do you want to shelve, for a rarity? Like how to invest,
> that is a very personal decision. Good luck to all.
>
> 73, Guy K2AV
>
> On Mon, Apr 17, 2017 at 11:32 PM, Doug Renwick <ve5ra at sasktel.net> wrote:
>
>> That myth refuses to die. I have 5 concrete tower bases with ground rods
>> partially encased and never a worry about an exploding base.
>>
>> Doug
>>
>>
>> -----Original Message-----
>>
>> -NEVER- encase a ground rod in concrete ... especially a tower base.
>>
>> As a retired 2-way radio tech, I'm aware of two towers that had to be
>> re-installed because of lightening strikes exploding their concrete bases.
>>
>> 73!
>>
>> Ken - K0PP
>>
>>
>>
>> ---
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