Backfill with bentonite or similar conductive earth material. I know a local
installer who puts up broadcast towers who did this and created a ridiculously
low resistance ground network on a rock mountaintop. Concrete is expensive!
Chris
KF7P
On Jan 18, 2016, at 10:59 PM, Roger (K8RI) on TT wrote:
> I was just wondering and no, I have no plans on changing my system: Yes, I
> am serious. The topic of UFER, ground rods and safety ground "systems".
> Would those of us with good soil benefit from boring a 6, 8, or 10" hole,
> filling it with concrete and sinking the ground rod in it? The contact area
> is small, but huge compared to the rod accompanied by a low inductance. It
> seems, at least in theory that the ground system could be reduced in size
> (number of rods) while possibly increasing the effectiveness of the system. A
> mini UFER ground system network. At first, it sounds like a lot of effort and
> cost, but out in the country, most of the equipment (Tractor mounted) is
> relatively common while those in the city could put down a much more
> effective ground system. Compared to the price of copper, particularly large
> copper , concrete is relatively cheap. From a practical approach, it'd be
> beyond many of us for a number of reasons. Availability and cost of
> equipment. In addition, damage to the yard although temporary could be
> vetoed by a spouse
>
> Barring math errors:
>
> Instead of many ground rods, how about concrete encased rods, in each
> direction if possible? The number of rods and the area is limited, so I
> would think this would greatly increase the effectiveness of said, limited
> ground system at a moderate increase in cost. An 8" diameter hole 8' deep
> would have a surface area of
> 16.75 sq ft
>
> Surface area = Pi * d * h Volume = Pi * 2d * h or Pi * r^2 * h
>
> Circumference = Pi*d 3.14159 X 8 = 25.132 X 8' X 12" = 2414.7412 sq in /
> 144 sq in (in a sq ft) = 16.755 sq ft of area A 5/8th in dia Ground rod is
> 5/8 0.624 * Pi = 1.962 * 8 * 12 / 144 = 1.3 sq ft. An 8" hole filled with
> concrete would offer 12.8 times the area while a 10" hole (20.0 sq ft
> offers) offers over 16 times the area. 10", 8' deep is roughly 4.4 cubic
> feet or 0.16 (1/6th) of a cubic yard
>
>
> 73
>
> Roger (K8RI)
>
>
> On 1/17/2016 Sunday 12:30 PM, Jim Brown wrote:
>> On Sun,1/17/2016 8:01 AM, StellarCAT wrote:
>>> I was thinking if I angled the rod at 45 degrees I’d both increase the area
>>> of the ‘coverage’ (out further away from the towers – UFER)
>>
>> Don't put your rods close to the concrete base to avoid interaction with the
>> UFER ground. Put the first ring of rods at least 4-8 ft from the concrete.
>>
>> 73, Jim K9YC
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