Some interesting ideas, thanks. I have a couple 3PH mounted augers
with blades for 6 through 12 inches in diameter and have built an
extension system to be able to drill deeper than the standard of about
40 inches, plus I have a 3PH mounted cement mixer powered by the
tractor's PTO so "drilling" holes and filling them with concrete is not
too inconvenient. what I can't do with my own equipment is auger deeper
than about 6 ft and I have to manually remove the "chips" with "Idiot
Sticks" (manual post hole digger) for the last 2 1/2 feet or so.
I'll be installing a new tower soon and this would be the opportunity to
do this fresh, not a retrofit.
I have a ton or so of bentonite as small granules and wonder if there
would be any advantage to adding some to the concrete. If yes, then how
much? Where should I look for that sort of info?
Glossary:
PTO is Power Take Off
3PH is three point hitch (rear implement mount on a tractor)
I would be please to hear comments regarding this sort of grounding
"enhancement" from the engineering side of the reflector.
Patrick NJ5G
On 1/19/2016 7:01 AM, David Robbins wrote:
concrete or bentonite encased rods are used for power lines in places that its
very hard to get a good ground. just how low a ground impedance (low
frequency) are you looking for???
Jan 19, 2016 12:59:55 AM, K8RI-on-TowerTalk@tm.net 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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