[TowerTalk] [Bulk] Re: RF Ground is a Myth

[David Gilbert]

You're going to need to duplicate the surface area of a typical Ufer 
conductor, and you're going to need to somehow bond it intimately to the 
bulk concrete.  I'll be interested to see what your test setup is, 
because I can't think of a legitimate method other than pouring some new 
concrete on top of the old with the conductor embedded in it.  Possibly 
you're more clever than I.

And you should probably be prepared to compare it to alternate schemes 
(ground rods, etc) to establish an appropriate baseline.

Dave   AB7E



On 1/20/2015 5:22 PM, Brian Carling wrote:
> I suspect it's not as conductive as some may have us think...
>
> Best regards - Brian Carling
> AF4K Crystals Co.
> 117 Sterling Pine St.
> Sanford, FL 32773
>
> Tel: +USA 321-262-5471
>
>
>
>
>> On Jan 20, 2015, at 1:22 PM, David Robbins <k1ttt at verizon.net> wrote:
>>
>> just remember when you do it to not use the point of an ohm meter probe.... it is not easy to measure bulk material resistivity like in soil or concrete or other types of materials.
>> you need to have some relatively large surface area to contact the material, which is hard to do with already poured concrete.
>>
>>
>> Jan 20, 2015 12:59:36 PM, bcarling at cfl.rr.com wrote:
>>
>> So far I am not convinced about using concrete. I'm going to do some resistance testing on the concrete in my yard.
>>
>> Best regards - Brian Carling
>> AF4K Crystals Co.
>> 117 Sterling Pine St.
>> Sanford, FL 32773
>>
>> Tel: +USA 321-262-5471
>>
>>
>>
>>
>>> On Jan 20, 2015, at 10:13 AM, Grant Saviers wrote:
>>>
>>> If your house slab was installed correctly with a vapor barrier and/or foam insulation, then it is insulated electrically from earth.
>>> Tower bases make good Ufers as do perimeter foundations, so my towers and shop both had the rebar set as Ufers when constructed.
>>> I also noticed that a new service transformer I had installed is set on a concrete vault that has a ground stub cast into the side. The power company used it, no ground rods. I'd estimate its surface area in contact with earth as more than 16 sq ft. Compare that to less than 2 sq feet for a 10' 3/4" ground rod.
>>>
>>> Grant KZ1W
>>>
>>>
>>>> On 1/19/2015 6:52 PM, Mike Reublin NF4L wrote:
>>>> The electrician I had (who does a LOT of grounding work here) come out to connect my tower ground to the service ground told me he would be glad to drive the extra rods extending out from the tower, but doing so would add no benefit at all. I have no idea if this is true or not. At some point, lacking personal knowledge, ya have to take someone's word for it. My tower megged out at 4 ohms.
>>>>
>>>> Mike NF4L
>>>>
>>>>> On Jan 19, 2015, at 8:29 PM, Brian Carling
>> wrote:
>>>>> The advice varies about this considerably. This week is the first time I've even heard of UF ER or conductive concrete!
>>>>>
>>>>> The professional experts that I know recommend putting a 20 to 30 foot ground rod into the ground at each corner of your house and connecting heavy gauge copper conductors up to lightning rodsup on the roof.
>>>>>
>>>>> It seems like if the only thing you need is a large area of this allegedly conductive concrete stuck in the ground, why not ground everything to the concrete slab your house sits on!!
>>>>>
>>>>> Best regards - Brian Carling
>>>>> AF4K Crystals Co.
>>>>> 117 Sterling Pine St.
>>>>> Sanford, FL 32773
>>>>>
>>>>> Tel: +USA 321-262-5471
>>> _______________________________________________
>>>
>>>
>>>
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