[Boatanchors] Testing a Ground connection

[Kenneth D. Grimm, K4XL]

I have found this thread to be a fascinating one.  The mention of 
megohms that was, I believe, in the original question was not as 
unreasonable as subsequent posts have tended to indicate.  I suspect 
that the confusion arises out of the name of the meter used to determine 
the quality of a ground.  It was known as a "Megger."  A "Megger" was 
used to measure the resistance between the ground rod and  reference 
rods placed in the ground at some distance away (50' and 100' 
typically).  A reading on the "Megger" of a few ohms was expected for a 
"good" low resistance ground. 

The company that manufactured "Meggers"  in this country was the James 
G. Biddle, Co. of Philadelphia.  In 1948 they published a 60+ page 
booklet entitled, "A Manual on Ground Resistance Testing."  It is 
available for downloading from BAMA as either a djvu file of less than 
1MB or as a pdf in a somewhat more corpulant 11MB size.  (Thanks to John 
D. Farr, KC4ZXX, for making it available).  I would recommend this 
thorough little booklet for anyone who is interested in the subject.  
I'm not sure that technology hasn't made the instruments more 
sophisticated today, but the principles described in the book are as 
valid today as they were in 1948.

Currently, the pdf file is available only on the main BAMA site at 
http://bama.sbc.edu/megger.htm and as many of you probably know the main 
site if frequently difficult to contact.  The mirror site at 
http://bama.edebris.com/manuals/megger/biddle currently has only the 
djvu version.  The pdf should propagate to the edebris site in a couple 
of days so if you have trouble getting the pdf from the sbc site, wait a 
couple of days and you will be able to download it from BAMA at edebris.

73,

-- 

Ken K4XL
k4xl at arrl.net

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