The "cone of protection" has, generally, been replaced by the "Rolling
Ball" method.
http://geospatial.blogs.com/geospatial/2012/07/designing-lightning-protectio
n-for-substations.html
73,
Don, WB2BEZ
In a message dated 1/28/2015 3:49:12 P.M. Eastern Standard Time,
xdavid@cis-broadband.com writes:
That was my thought ... ground rods spaced along the way to try to make
the effective "antenna" of the ground wire shorter. Not sure if that's
what actually happens or not.
73,
Dave AB7E
On 1/28/2015 11:57 AM, Patrick Greenlee wrote:
> The old rule of thumb for lightning protection from over head
> dissipation devices (high metal roofs, lightning rods, grounded
> towers, etc. is a 30 degree cone angle. This is NOT a guarantee but a
> tendency. I think more is better and would not find fault with a
> ground wire a ways above coax or control leads but would encourage
> ground rods along the way so as to not encourage a great deal of
> coupling between lightning generated ground wire and "other"
> conductors below it.
>
> Patrick NJ5G (now stand by for a total debunking of my comments...)
>
>
> On 1/28/2015 12:30 PM, David Gilbert wrote:
>>
>> I don't have the expertise to be sure about it, but it always seemed
>> to me that it would be best to run the ground wire (grounded at both
>> ends and maybe a few places in between) in the same trench as the
>> coax ... but some distance above them ... in order to provide a sort
>> of shielding effect for the coax against induced currents from nearby
>> lighting bursts. I was once told that the electric utilities run a
>> ground line at the top of utility poles above the actual power lines
>> for a similar purpose.
>>
>> Possibly induced currents in the ground wire would still couple to
>> the coax anyway, but I certainly don't see how running the ground
>> wire with the coax would be any worse than running them separately.
>>
>> 73,
>> Dave AB7E
>>
>>
>>
>> On 1/28/2015 8:43 AM, Cox, Norman R. wrote:
>>> Dear Group:
>>>
>>> I am now ready to connect the tower grounding rod network to
>>> the shack grounding system. The crank-up tower is about 30 feet
>>> from the shack. Is it preferable to run the ground connection
>>> between the two along with signal cables? Or is it better to run
>>> the grounding connection not so close to the signal cables? I've
>>> seen people do it both ways, and can see a possible benefit either
>>> way, but a lightning strike could throw either idea out the window.
>>>
>>> Thanks,
>>>
>>> Norm
>>> KE0ZT
>>>
>>>
>>> _______________________________________________
>>>
>>>
>>>
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>>
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