[TowerTalk] ground rods and angle...

[Chris]

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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