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method fail to measure.
(1) Two -point method
As shown in the following picture, find an independent ground body RB with good
ground near the ground body RA being measured ex. adjacent metal running
water pipe, metal fire hydrant, building etc. and connect RA with RB by a test line.
Test line
As resistance measured by the clamp meter is the parallel value of 2 ground
resistance and test line resistance,
RT=RA+RB+RL.
Of which, RT is the resistance measured by clamp meter and RL is the resistance
of test line.
Resistance RL could be measured by clamp meter by connecting the test line
end to end. If measurement value of clamp meter is smaller than the allowable
value of ground resistance, ground resistance of the two ground bodies shall be
qualified.
(2) Three-point method
As shown in the following picture, find two independent ground bodies RB and
RC near the ground body RA being measured. If no existing independent ground
body, make 2 auxiliary ground polarities with 3-5m distance between them and
about 0.7m depth each.
Step1, connect RA and RA with a test line, as shown in the following picture, and
read the first data R1 by clamp meter .
UT276A/278A OPERATING MANUALUT276A/278A OPERATING MANUAL
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