[Elecraft] OT: Groond rods and concrete

[Walter Underwood]

House grounds and tower grounds are designed for different hazards (and risks, which are hazards with dollars).

Direct lighting strikes on houses are less common than power line surges. So house grounds are designed for surges, which can be large. A direct strike on a stucco house is going to vaporize the wire mesh and blow the stucco off in several places. Ground rods won’t help that much.

A tower is much more likely to get a direct strike. The grounding system on a tower is designed to survive a feeder strike and reduce the destruction (risk) of a direct strike. Better to melt the coax than burn down the transmitter shack.

When I was in high school in Indianapolis, my next door neighbor was a ham with a tower. He had worked on lighting arrestors at GE. He explained that a lighting pulse had so much high-frequency energy that it more followed than conducted along a ground strap. It jumps from the strap to the building and back about every two feet. Lightning systems are a hint, not a directive. Nobody tells lightning what to do.

I like what I do, but working on lighting arrestors? That would be COOL.

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Apr 17, 2017, at 4:16 PM, Wes Stewart <wes_n7ws at triconet.org> wrote:
> 
> Clearly, you have something in mind different from me.
> 
> https://www.tessco.com/products/displayProductInfo.do?sku=12952
> 
> Tell me how you avoid the exploding concrete myth using something like this?
> 
> Or with a bolted base plate:
> 
> https://www.cableandwireshop.com/rohn-45g-tower-concrete-base-plate-r-bpc45g.html
> 
> Read the last sentence.
> 
> 
> On 4/17/2017 3:25 PM, Bill Johnson wrote:
>> No, unless adequate steps are taken to assure a large ground grid is made.  This requires more than just a slab.
>> 
>> 73,
>> Bill
>> K9YEQ
>> 
>> -----Original Message-----
>> From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Wes Stewart
>> Sent: Monday, April 17, 2017 5:17 PM
>> To: elecraft at mailman.qth.net
>> Subject: Re: [Elecraft] OT: Groond rods and concrete
>> 
>> Isn't the tower base pretty much a ground rod?
>> 
>> On 4/17/2017 2:16 PM, Rose wrote:
>>> -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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