[TowerTalk] A "better" ground.
Eric Scace
scace@uu.net
Fri, 29 Oct 1999 04:39:19 -0500
Hi Mike --
There is no problem tying in your ground system to a well casing, and, in
fact, it is probably an excellent idea.
Note that I said "ground system". That means the ground rods around the
tower, plus the ground(s) established at the house/shack, and the ground
wires/strap connecting all that together. Everything that is "ground"
should be tied together with ground wires/strap. This way, when a charged
cloud moves overhead, or a strike occurs nearby (or even on) your site, the
entire system's electrical potential will rise and fall together.
If you do not tie everything together, then currents (direct or induced)
will flow between the points of grounding over any other electrical wiring
available. That means significant current flow could be induced into your
well pump power lines, for example.
Note: This is a very brief summary of a complex topic. For a better
understanding, please see the Polyphaser Application Guide that has been
cited many times here on the TowerTalk reflector. (Do a search of the
archive if you are a new participant.)
Now, for the anecdotal story: I have had for 19 years a mountaintop
location that is 1300 feet surrounding average terrain in Maryland. I have
two towers, grounded with a 6 foot rod driven below the concrete base (and
tied into the metal infrastructure in the concrete) plus a constellation of
three rods driven about 10 feet away from the base, all tied together. The
two towers are tied to each other by grounding wire. Because of the
distance between the towers (400 feet) and the shack (300 feet), the ground
wire is grounded with a constellation of three 6-foot rods every 100 feet.
The well casing (450 foot well, but metal casing only goes down 40 feet) is
also tied in, as are the utility ground and a ground system at the radio
cable entrance hut (where the Polyphaser surge suppressor panel is mounted).
Over the years I have seen a lot of lightning. The towers (126 ft and 86
ft) have never taken a direct hit that I have been able to detect --
although I've had plenty of nearby strikes induce significant current flow.
(I have a strike counter, also available from Polyphaser.) But in 19 years
I have only had one piece of equipment damage: a 2 meter radio that was on a
temporary feedline which did not have a surge suppressor installed!
Follow the Polyphasor recommendations strictly. It works.
-- Eric R3/K3NA
Last note: You said your well is 285 feet deep. It is very unlikely the
metal well pipe you see goes down 285 feet. The metal pipe is normally
provided for only the top 20 or 40 feet. It serves to prevent the soft
upper layers of soil and loose rock aggregate from falling into the well.
Once the drillers hit bedrock, no pipe is required. Depending on the level
at which water enters your well, and the height of the water column, the
well casing may not be in contact with your water column. But it still
represents a very good deep ground. Observe the precautions mentioned in
earlier threads about connecting dissimilar metals (e.g., copper wire to
soft steel pipe) when you hook up your ground. And you can install a power
line surge suppressor where the wires coming up from the well pump exit the
well casing (the pipe) before beginning the underground run. That way, any
significant voltage differential between the well pump wiring and the well
casing will be equalized.
Sorry for the long response.
-----Original Message-----
From: owner-towertalk@contesting.com
[mailto:owner-towertalk@contesting.com]On Behalf Of mike dunlap
Sent: 1999 October 28 Thursday 17:22
To: towertalk@contesting.com
Subject: [TowerTalk] A "better" ground.
Hello All!
My grounding question is one of utilizing a water well cap/ pipe that is
sunk into the ground 285' for our home water or to just use the traditional
8' rods at each end of the tower .
My only concern about using the well cap as a ground would be that of
damaging the motor that is down inside the well pipe if a "hit" were taken
thus NO water for the house. However since the tower is only 7-10' from
the well cap anyway and if a "hit" were to take place using the
"traditional" grounding would it really matter.....for the well motor that
is?
Any and all ideas, comments and suggestions are very welcome! The entire
project, tower and all will be erected next spring.
Please note that here in WI we live up on a hill and the soil is very dry
and there is much rock and clay below the first 2-3' of soil.
Thanks for your help and I look forward to your replies!!
'73 from Mike in Hudson, WI!
K0NWA
mdunlap@pressenter.com
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