As the resistance value measured by the Meter is the value of the
series resistance from the testing line and two grounding
resistances.
R
T
=R
A
+ R
B
+ R
L
Where: R
T
is the resistance value measured with the Meter.
R
L
is the resistance value of the testing line.
Meter can measure out the resistance value by connecting the
test lines with both ends.
So, if the measurement value of the Meter is smaller than the
allowable value of the grounding resistance, then the two
grounding bodies are qualified for grounding resistance.
(2) Three-Point Method
As shown in the figure below, in the vicinity of the measured
grounding body R
A,
find two independent grounding bodies of
better grounding state R
B
and R
C.
First, link R
A
and R
B
with a test line; use the Meter to get the first
reading R
1
.
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