[TowerTalk] Earthing a tower

[Jim Lux]

On 1/1/13 8:21 PM, K8RI wrote:
> On 12/30/2012 2:14 PM, ve4xt at mymts.net wrote:
>> Another repetition of the exploding base myth.
>>
>> If concrete is so explosive, and such a poor conductor, why is it
>> often used to assist with rod-earth connections?
>>
>> As well, the very existence of the Ufer ground pretty much debunks the
>> exploding base mythology.
>>
>
> The NWS even has  video showing what could be construed as the exploding
> base and it is no myth, BUT we need to be able to separate cause from
> hearsay.
>

Can you provide a URL or something?  I tried googling "NWS concrete 
damage lightning" etc and couldn't turn something up.

I did find a LOT of pictures of concrete damaged by lightning, but none 
of them were a Ufer ground.. More things like a sidewalk hit by 
lightning, or a concrete block wall with a big crack.




> I have seen pictures of concrete blown apart from lightning strikes and
> some of those were from the NWS so I believe them.  However in those
> cases we need to ask WHY did the concrete either blow apart, or crack so
> badly it had to be replaced.


Yes.. the ones I saw were not a Ufer style ground.



In the course of my googling, I also learned about Bruce McCain or Max 
Mccomb (I saw both versions of the name), who was an electrical 
contractor responsible for grounding ski-lift towers in the Sierra 
Nevada. His success with the Ufer ground led to his advocating it for 
the NEC.

Of course, this is hearsay so far.. haven't found the original info. 
Just "did you know about x..." kind of stuff in a forum or website.


One common thread in all the discussions I've read where spalling did 
occur was that either
a) it wasn't a grounding system issue.. it was somewhere else in the 
structure
b) where it was a grounding system, everyone concerned thought that 
nothing would have done any better than the Ufer ground, and probably worse.
>