Code does not define how to measure resistance of earth
ground. The same application notes that demonstrate how to
install a more serious 'single point earth ground' (which is
labeled MGB in the picture):
http://www.leminstruments.com/pdf/LEGP.pdf (figure on page
14 or)

http://leminstruments.com/grounding_...ml/index.shtml
(section entitled "Measuring Ground Resistance at Cellular
Sites,Microwave and Radio Towers")

That Lem Instrument application describes measuring earth
ground resistance since that is what they are selling.

'nuther Bob wrote:
On Sat, 12 Jul 2003 19:13:36 -0400, w_tom wrote:
Code does not define how that earth resistance is to be
measured. Most locations will get less than 25 ohms with only
one ground rod.

What do you do to measure this ? Stick one lead of the meter on
the rod and another in the ground ? How far away would you put
the ground lead ?

I can see this having a serious variation in my area in the summer
dry season. The rest of the year is probably wet enough to get some
conductivity.