IN SEARCH OF 5 OHMS !!
Kg4w at aol.com
Kg4w at aol.com
Thu May 9 01:37:38 EDT 1996
Well, since my grounding system is very
poor (dont have any) I got me 13 eight
foot gnd rods 5/8' dia and decided to go
pound some copper. These are the rods
that are threaded on each end and spliced
together with a threaded sleeve. Rods were
abt 6.00 each & the threaded sleeves are
5.00 ea. or so sez my son (the electrician).
I got son to bring along the "electric driver"
which they use, it looks like a humungous
electric drill but insted of a chuck, its got a
steel shaft that plunges in & out inside a
pipe that fits down over the rod. This tool is
not for "lightweights".
Anyway, I did a little reading and found that
the Power Co supposedly looks for a 25 ohm
or better ground and communications sites
stipulate 5 ohms or better so I decided to go
for a 5 ohm ground. Got a "Biddle Det 2/2
ground tester (loaned to me) and I started
"driving" First 8 ft rod measured 105 ohms !!!
screwed on anouther & drove it (we now down
16' = 64 ohms. Screwed on 3rd and drove it
we now got abt 27 ohms & we at 24'. Attached
4th rod and managed to finally get it in all way
and the 32ft rod measures around 14-15 ohms.
So still being in the "driving mood" after resting
up a day or so I began installation of the 2nd
rod (to ultimately be tied to the 1st) Now ground
rod rule # 1 sez that rods which will be bonded
together should be seperated by a distance equal
to (at minimum) the depth of the rods in de ground.
This minimum separation is supposed to result in
a overall gnd resistance of 40% better than the
single rod & if the spacing is doubled, then the
reduction becomes 50% etc. Since my "windmill"
tower is abt 60 ft from 1st gnd rod I decided to sink
rod 2 there. Took first rod and just pushed it into
soil "by hand" for 1st 5', but thats where the
"by hand" method stopped !!. This was the same
with 1st rod also. Got 2nd rod down abt 28 ft and
i think thats gonna be it for that one. My "water"
table here is arnd 25' down and shortly below that
its "hard pan". Second rod by itself measures abt
17 ohms. With the 2 tied together (& allowing for
the 1.25 ohm res of the test "tie together" wire),
I get around 6 to 7 ohms which is in line with
ground rod rules. Why am I writing this ? I dont
know !! I know I'm worn out !! I know 1 thing, I
bet theres not at residential Power Co ground
anywhere around here that is 25 ohms or better !!
cuz to get that u gotta go 24' or have multiple
rods. This is a "well water & septic tank" area
so guess we still catagorized as "country".
There are 2 telephone co type ground rods here,
these are the small 4' rods so I decided to
measure them- 1 meas 416 ohms !! other
abt 250 ohms !! So I havent gotten my 5 ohms
yet but by time i tie the 2 rods together with
6 inch wide "copper flashing" plus a "cadwelded"
4 ought wire (all bare & buried) it'll probably be
close to it.
The screw together rods work nicely but u
have to continiously tighten them as u drive um.
Even tightening each joint with 2 pipe (stilson)
wrenches as tight as i could, the rods would
want to work loose. The driving tool is a bear
to use but is a life saver. I still had to use the
4lb hammer to get through some tough spots.
I think i am down as far as i can go, my son sez
hes been down 100' with um, but its not been
in this area !! When driving these rods, you attach
a sleeve to the top of the rod being driven and
then screw a steel "bolt" into the top of the sleeve
and this bolt is what u (or the machine) drives
against so you dont tear up the sleeves or rods.
The Biddle test set is a beauty, you just attach
a test wire from the set to the rod ur driving (or
to a rod thats already been driven) then drive a
"test stake" (comes with test-set) 100 ft from
rod under test and connect test stake to test set.
Then u drive 2nd test stake 62 ft from rod under
test ( all in stright line) & attach this stake to test
set and push de button & in few seconds , de
lcd display gives u the resistance of the rod in
Maybe this info will be of some help to others
of you who may be searching for that "low
resistance path" for lightning to follow. After I
stop "driving" then I'll begin to attempt to try
to protect the 12 coax's and mass quantities
of rotor/switching cables that enter the shack.
73 Ed KG4W (my arms hurt)
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