-12-
Simple method for measurement of earth ground resistance, its reading
on Tester is the total value of earth ground resistance value of measured
ground object and that of commercial ground object, namely:
RE=RX
＋
re
In which:
RE
is the Tester reading value;
RX
is the earth ground resistance value of measured ground
object;
re
is the earth ground resistance value of common ground
object like commercial use power system.
Then, the earth ground resistance value of measured ground object is:
RX=RE
－
re
Adopting simple method for measurement of earth ground resistance
shall try to select the ground object with low value as the auxiliary earth
ground electrode and thus the tester reading value can be more
approaching to true value. Please take precedence in selecting metal
water pipes, fire hydrants as auxiliary earth electrode when measuring,
and refer to the following figure for application.
Grounded object
being measured
Commercial
grounding object
Secondary
Primary
Transformer
Green
Red
