TT and John,
Thanks John - that is very interesting. I have 9 (nine) 8 foot ground
rods around the base of the tower. I do NOT have them connected with a
large outer circle but may do that. I do have them all connected to the
tower and groups of 3 are connected to each other with bare # 4 cooper
wire - solid: 1 ground rod (8 feet) at each leg of the tower with 2
more connected to each of those for a total of 9 ground rods. I then
have a large wire going from one of those ground rods about 35 feet over
to the house electrical entrance and connect to the ground rod there -
and during the length of that 35 feet I have 3 (three) 6 foot ground
rods spaced evenly.
So, a total of 13 ground rods connected with #4 bare cooper. I hope
that provides some protection. In addiction I have an I.C.E. rotator
cable 8 conductor arrestor mounted at the base of the tower. And I use
an Array Solutions RatPak remote switch which has MOV protection.
I have just ordered a coax surge protector (one for HF and one for
VHF/UHF) that I will probably install near the shack on the one hf line
coming from the rat pak and the one VHF/UHF coax coming into the shack.
I ordered the I.C.E. coax protectors designed to mount directly to a
ground rod and I have another 6 foot ground rod for that purpose I plan
to actually make a hole in the floor to the side of my shack and put it
into the ground there with the coax protectors mounted directly on the
ground rod.
So, am I ready for a strike? I don't know - and I would like to get the
ground resistance measured but don't know of anyone in rural north Texas
that would do that reasonably. Other than the ground resistance I am
thinking about putting in two circles with #4 wire connected the first 3
ground rods from the tower and then the 6 ground rods with a larger
circle. The 8 foot ground rods are spaced 16 feet apart. Ideas
appreciated?
Gary, N5PHT
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of John E.Cleeve
Sent: Thursday, June 08, 2006 8:27 AM
To: TowerTalk@contesting.com
Subject: [TowerTalk] Ground resistance
----- Original Message -----
From: John E. Cleeve <g3jvc@jcleeve.idps.co.uk>
To: 'Stone, Gary R . ' <Gary.Stone@va.gov>
Sent: Thu Jun 8 14:34
Subject: Fwd: Re: [TowerTalk] Ground resistance
Hello Gary,
I asked the same question. The answer was that the measurement device
cost around 1400 pounds sterling, so I decided to ask a company that
specialised in installing lightning protection for church towerers
etc. They came to my house and measured the ground resistance by means
of a bridge type meter, putting out test leads around the site etc.
They came up with a reading of 19 ohms, between my own "earth rod",
and the site boundarys, and said that figure could be improved on. I
agreed that they should continue the work, and they proceeded to drive
three copper ground rods into the soil, using a Kango hammer, at the
corners of an 8ft triangle, where my tower base is in the centre of
the triangle. They measured the ground resistance as each length of
copper went down, and once the three ground rods were driven to a
depth of 4 metres, the measured ground resistance was just 2.1 ohms, I
saw the meter reading, and I have a certificate to prove it. The
surface ends of the copper rods were then tied together, using 1 inch
wide, thick copper strap, and the top of my crank up tower, connected
to this ground system by means of a flexible copper conductor of an
equal cross section. The entire job took about 1 hour, and the cost,
about one third the price of the test equipment required to do the
measurement......I hope this may be of some interest to you and the
group....sincerely,
John. G3JVC.
On Wed Jun 7 19:09 , 'Stone, Gary R.' Gary.Stone@va.gov> sent:
>Greetings,
>
>
>
>I imagine I have missed the obvious but my question is how do you
>measure ground resistance? Does it take a special meter (I suspect it
>does). I am writing this in reference to ground rods and grounding of
>towers.
>
>
>
>Thanks,
>
>
>
>Gary, N5PHT
>
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