I note the use of the term, "most common." What is most common is not
always the best performing or the most bang for the buck. Time was when
the belief in a flat earth was most common, man would never go to the
moon, the earth was the center of the universe, and on and on. Being
common is not necessarily a positive recommendation.
Empiricism implies valuing what " I S " over what someone may have
theorized. Ufer grounds are not an ivory tower theoretical concept
waiting to be proven but practical performers that have been proven to
work under difficult conditions. As to their performance in dry soil as
desert sand etc., that is to their credit that they can offer higher
performance than copper clad steel rods under difficult conditions.
Working well under difficult conditions in no way lowers their
usefulness under more ideal (more moist) conditions. Do not be mislead,
their being favored for "DRY" conditions does not make a negative
statement regarding their moist performance.
So, in fact if someone actually does want something that works then they
should consider Ufer grounds when contemplating making a grounding
system. As far as Ufer grounds putting copper clad steel rods "out of
business", not to worry as there is enough inertia to keep rod sales
going for a good long time. There are applications where rods may be
easier, cheaper, or more convenient but superiority is not automatically
granted to ideas or processes because they predate their competition.
Germ theory, heavier than air flight, space travel, and so on and on.
There a a jillion examples of defense of old ideas railing against newer
ideas that couldn't possibly be valid.
I know people who are still waiting for color tv to be perfected before
they give up their old B&W set.
Patrick NJ5G
On 1/21/2015 8:40 AM, bcarling@cfl.rr.com wrote:
Empiricism is probably my greatest strength and perhaps weakness in my survey
of concrete
possibilities. I like things that work rather than what is calculated to work.
I will probably not use or need a UFER Ground. I am not doing new construction
so that
possibility is out unless I want toi jack hammer through to some rebar. "Ain't
a-gonna do
that."
I will just be interested to see what comes up with a multimeter / ohm meter
measurement using probes or something else to come into contact with some
concrete.
I am guessing most radio amateurs still prefer copper clad steel ground rods
rather than
some kind of concrete pillar that you can't buy or install conveniently.
Wikipedia says that UFER ground is for dry areas. If the soil requires it.
These are just things
I am reading.
Also - one theme is recurrent:
"If Ufer grounding alone was enough, the manufacturers of ground rods would go
out of
business. But a Ufer ground alone it is not adequate. Few buildings, even those
under
construction today are built to take advantage of the Ufer ground. It is common
to see the
use of "Ufer grounding" in military installations, computer rooms, and other
structures with
very specific grounding specifications. It is not common in most industrial
plants, office
buildings and homes. More common today is grounding to national and local
electrical codes.
This will involve one or more driven ground rods connected (bonded) to the
neutral wire of
the electrical service entrance. The purpose of this bond is what is known as
life safety
ground. It is used for many other things but the code required life safety
ground is why it is
there to begin with."
On 21 Jan 2015 at 0:08, David Gilbert wrote:
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@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@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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