Megger Limited
PWS / Nov 06
DET4TC/R Launch
20
Now look at the next diagram.
In this situation the electrode under test is very close to the building. The result is the
sphere of influence of the electrode and that of the building are overlapping.
Effectively we now have “earth coupling” occurring, hence the difference in
equivalent circuit.
The overlap in the spheres of influence introduces additional impedances that make
resolving the resistance of the electrode difficult using ART. The result will cause
either be the “clamp low” symbol appearing or an unexpectedly high reading. If this
happens proceed with the traditional 3-pole method with the electrode under test
disconnected.
P
X Test point
C
