Topband: earth tester

[Paul Christensen]

> "Do you use a earth tester?  Which brand do you know is very good and 
> accurate to consider?"

Jorge,

If you can, try and find a "clamp-on" earth tester rather than the type that 
relies on the fall-of-potential method with electrodes.  There are several 
good clamp-on units by Megger, Fluke and AEMC.   I recently acquired an AEMC 
model 3711.  It wasn't supplied with a calibration loop, but I found one 
from Fluke that quickly checks calibration at 100, 50, 12.5, and 0.5 ohms. 
You'll want that calibration loop to validate the accuracy of the clamp 
tester, especially if you use an off-brand model from Asia.

N4CC and I recently installed a large grounding field, with some ground rods 
driven down to a depth of 24 ft.  The clamp-on device was useful for quick 
validation.  Had we used a unit with electrodes, it would have taken us much 
longer to perform our tests.  By the way, in sandy/clay type soil here in 
north FL, we found that connecting 8 ft. rods end-to-end to form a 24 ft rod 
substantially lowered earth resistance by a factor of 10x.

Paul, W9AC