Thanks for the advice. I think my best course will be to test the
soil conductivity. The only time we have lightening here is during
the summer storms; the soil is usually damp from the sprinklers all
summer so it's probably better with no concrete. Does anyone know the
conductivity of concrete offhand? I guess I could always ask google,
although it probably depends on the aggregate. Local aggregate has a
pretty high iron content and I expect would conduct fairly well,
unless the paste is a good insulator.
Brian
KF7OVD
On Thu, Apr 24, 2014 at 10:10 PM, Mike Fahmie via TowerTalk
<towertalk@contesting.com> wrote:
> It all depends on the conductivity of the concrete versus the local soil.
>
> Ufer grounds excel in soils with poor conductivity (dry sand is an extreme
> case), but it makes no sense to wrap your ground rod in a material that has
> poorer conductivity than the soil surrounding it. Concrete can be a much
> better conductor than poor earth but worse than earth with good conductivity.
>
> I chose the Ufer path because my 'soil' is dry hardpan that resisted ground
> rod drivers and I felt that the large contact area of the concrete would
> makeup for the soils poor conductivity.
>
> -Mike-
> WA6ZTY
>
>
>
>>________________________________
>> From: Roger (K8RI) on TT <K8RI-on-TowerTalk@tm.net>
>>To: towertalk@contesting.com
>>Sent: Thursday, April 24, 2014 8:14 PM
>>Subject: Re: [TowerTalk] Ground Rod Myths?
>>
>>
>>On 4/24/2014 1:36 PM, Brian Amos wrote:
>>> I have the equipment to drill a 6 inch hole through just about
>>> anything, what if I placed my grounding rods in concrete or grout?
>>
>>I would think it wouldn't hurt. It might act as a small UFER ground.
>>increasing the contact area of 20 inches Vs 1.9 inches or almost 11
>>times the area of the single ground rod.
>>
>>How well that'd hold true? I don't know.
>>
>>73
>>'
>>Roger (K8RI)
>>
>>
>>
>>> Would that help or hurt the grounding? I do have a ground resistance
>>> meter I use for work for providing soil resistance values for
>>> grounding communication towers and equipment so I could test it I
>>> suppose, but I usually like to know what I'm getting myself into. I
>>> have seen them drive a steel lathe (about 3/4 inch in diameter) into
>>> slightly weathered bedrock with a post pounder on a bobcat. The
>>> cobbles and boulders just cause it to move a bit to the right or left.
>>> Of course the commercial towers I do the foundation design for
>>> usually have a grounding grid surrounding them. I am tempted to see
>>> if one of the tower engineers will design my grounding system with a
>>> similar system, they tend to suffer little if any damage from
>>> lightening, and being on mountain tops I am sure they are struck quite
>>> often.
>>>
>>> Brian
>>> KF7OVD
>>>
>>
>>
>>_______________________________________________
>>
>>
>>
>>_______________________________________________
>>TowerTalk mailing list
>>TowerTalk@contesting.com
>>http://lists.contesting.com/mailman/listinfo/towertalk
>>
>>
>>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|