[SMCARA] Semi-Easy Ground Rod Insertion

Mon Sep 15 12:43:32 EDT 2014

Good point, Bill.

Some interesting reading on the subject may be found at: www.arrl.org/lightning-protection , www.arrl.org/grounding ,  www.polyphaser.com , http://stormhighway.com/protection.php ,
 http://www.elec-toolbox.com/usefulinfo/lightprot.htm , www.w8ji.com/ground_systems.htm , www.radioworks.com/nbgnd.html , http://kc.flexradio.com/KnowledgebaseArticle50426.aspx

Although a bit esoteric by ham standards, I observed an interesting grounding system at a Sandur LORAN C station in Northwest Iceland.  The antenna was a 1350 foot tower, with an impressive 120, 1000 foot radials on the ground, not buried. The base of the tower was bonded to a field of ground rods via a gas discharge system (think PolyPhaser, etc.) since it was a "hot" tower. Each radial had ground rods every 100 feet in addition to the ones at the base of the tower.  The 3 Megawatt, 100 KHz transmitter fed the antenna via a matching unit (helix house) and large diameter hard line.  At this power level the RF currents were pretty impressive, so all connections were accomplished with a process called Cadweld. This is an exothermic welding system for the heavy (1/2 inch, stranded copper cable) radials and jumpers. This provided lightning protection as well as an efficient RF ground system.  This may seem a lot, but the ground resistance of the volcanic rocks up in Iceland is quite high (inefficient).  If you have good ground conductivity, fewer ground rods and radials will work.

This station is now gone, but one bit of trivia remains.  The station was located a few miles North of Snaefflsjokul volcano, which where Captain Nemo's submarine Nautilus entered the underworld in the Jules Verne story, "Journey to the Center of the Earth". Although the station is gone, you can go to 63.849957,-22.45863 on Google Maps and see a typical VLF installation.  This is the VLF transmitter at Grindavik IC.  You can see the two towers, 1200 and 600 feet with the outline of the ground radials. Pretty impressive.  You also can see some of the HF antennas south of the site.

Tom/W4OKW

-----Original Message-----
From: SMCARA [mailto:smcara-bounces at mailman.qth.net] On Behalf Of William S Merritt
Sent: Sunday, September 14, 2014 6:52 PM
To: smcara at mailman.qth.net
Subject: Re: [SMCARA] Semi-Easy Ground Rod Insertion

Unfortunately this 'wet' method does NOT meet either National Electrical Code standards for a safety ground nor for an RF ground.

NEC code requires a safety ground rod to be driven in 'undisturbed
earth'.   By washing out soil you disturb the native soil and reduce its
conductivity.

This method can be used with enhanced ground rods.  That is a hollow rod
(pipe) with holes in it which is either driven into the soil or more commonly, placed in a hole which is back filled.  The pipe is then filled with salts such as common rock salt or Epsom salt, magnesium sulfide.  It is then wetted and repeatedly packed.  Periodically it must be serviced with more salt.

Ordinary copper plated rods make poor RF grounds without additional
radials.   Enhanced grounds may be used for safety or RF grounds.

73, Bill
KB4QAA

On 9/13/2014 2:34 PM, Bill Jones wrote:
> Just used it to install my ground rods. Just got a little wet on occasion.
> There are a lot of videos on the Internet on this also. But parts are
> ;
>
> 10' 5/8ths O.D. emt conduit
>
> 1 5/8" Water hose repair kit which  uses the Brass Connector and
> tapered end for inserting into the hose
>
> 1 5/8" Adapter with a turn valve to turn the water on and off
>
> About 8 to 10 dollars in parts.
>
> Had a neighbor heat one end of the conduit and hammer it in place
> using scrap 2x4 piece then once in and lucky for me he has an
> air-compressor used an air hammer to get it the rest of way in. The
> other way we were going to do it once it was in far enough was to use
> a plumbers torch kit you buy just about anywhere and solder the two
> together together but this worked well.  I also marked from hose end 3
> marks with a marker, one for 9', one for 8' and then 2" so that I
> could add the clamps and wire and then due to soft soil hammer the
> rest of way in but no beating it or go to 8' mark and then hold rod in
> place. Next hook a hose to the end and turn water on at main. Then
> using a ladder place the conduit into position in a small hole I
> started to keep pipe below ground. Turn on the water and pump the rod
> up and down and let water do the work. Depending on ground it took me
> 20 min on first and 15 on the other. No beating it. Have run the
> ground wire (#4
> Solid)  from crawlspace with enough slack to run up to room. Then ran
> that to the first and second rod. Still need to connect to the power
> ground but may drop one more rod first. But so far it not too much
> headache. Just a little wet now and then and kneeling in wet soil.
> Wear old clothes. Of course as per working outside the house exercise
> caution and know where the power and cable, telephone, etc is. Contact
> Miss Utility if you need to. No need to irritate a neighbor or have a
> bad day with hitting something you should not. If anybody wishes to
> borrow this tool, its available for use once I get the last rod in tomorrow or Monday.
>
> Bill
>
> KC3DEZ
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--
Bill Merritt
KB4QAA/3

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