I'm a researcher prologue that the National Severe Storms Lab in Norman, OK.
There's a fair bit of lightning research done here, mainly on the physics of
lightning. I know a few of the guys that do the research though I'm not
involved in any of it. That said, I'm not sure where hundreds of thousands of
amps number comes from. The highest-current strikes are single-stroke positive
flashes. They tend to peak around 50 kA or so. I'm not sure what the
distribution of peak current looms like, but 100 kA is rare. According to
Martin Uman's book, only about 6% of all flashes produce currents larger than
60 kA; the median peak current is 15 kA and the highest current recoded was 218
kA. While these numbers are admittedly old, they are certainly representative.
Kim N5OP
"People that make music together cannot be enemies, at least as long as the
music lasts." -- Paul Hindemith
> On Aug 8, 2015, at 16:57, Jim Lux <jimlux@earthlink.net> wrote:
>
>> On 8/8/15 2:33 PM, N3AE wrote:
>> Concerning lightning damage to a concrete foundation .... ran across the
>> example in the link below. In this case a concrete guy anchor was damaged.
>> But looking at the pictures, this might have been caused by moisture entry
>> due to surface cracking with the lightning strike just finishing it off as
>> the current pulse turned the moisture into steam. Hard to say.
> and this quote covers why "commercial" installations (where labor is a big
> cost) are different than "ham" installations (where labor is often free);
> "the conductors are really a small portion of the overall cost of the job"...
>
>
> "Deep-driven rods in combination with heavy copper cabling have proven to be
> an effective, reliable and durable solution. And don’t skimp on the copper.
> Use large conductors, not ‘Code Minimum’ sizes. The conductors are really a
> small portion of the overall cost of the job.
>
> “Install ring grounds and radials if there’s room, and bond all connections
> properly. In a major lightning strike, you’re potentially dealing with tens
> of thousands to hundreds of thousands of amps. Copper is cheap insurance
> compared with the equipment damage that could occur if the system is
> inadequate. In the case of the KPTH-KMEG tower, another strong hit might have
> led to very expensive repairs … or worse.”
>
>
>> I think the real question is if a lightning strike can cause internal damage
>> to a tower concrete foundation that you can not easily detect.
>>
>> N3AE
>>
>> http://www.copper.org/applications/electrical/pq/casestudy/a6137/a6137.html
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