-1
4
-
6
．
3-Wires Earth Resis
t
ance
Measurement
3-
wires measurement:
As shown below, short-circuit
ES
and
E
interface
.
The operation of meter is the same with
4
wires measurement
but,
t
he
3-
wires method
cannot
eliminate
the
influence of
line
resistance,
or the
influence of contact resistance
between meter and
testing wires or
between testing wires and probes. Oxidation layers on
probes must be
removed when measuring.
7
．
2-Wires Simple Measurement
Using
simple
2-wires method for measuring earth
resistance, choose a
earthing
body which has a small
re
value as auxiliary earthing
probe
, so that the reading value is
more close to the
actual
value.
Buried
metal pipes
or
metal
fire hydrant
would be priority
auxiliary earthing
probes
.
d= Probe Depth
