Field Applications - AEMC 3710 User Manual

Field Applications

Pole Ground Rods
Remove any molding covering the ground conductor, and provide suffi-
cient room for the jaws of the clamp-on. The jaws must be able to close
easily around the conductor. The jaws can be placed around the ground
rod itself.
Note: The instrument must be placed so that the jaws close around an
electrical path from the system neutral or ground wire to the ground rod
or rods as the circuit provides.
Select the current range "A." Clamp onto the ground conductor and mea-
sure the ground current. The maximum range is 30.00 A Trms. However,
if the ground current exceeds 5 A or noise exceeds 50 V, ground resis-
tance measurements are not possible. Do not proceed further with the
measurement. Remove the instrument from the circuit noting the location
for maintenance and continue to the next test location.
After noting the ground current, select the ground resistance range (Ω)
and measure the resistance directly. The reading you measure with the
clamp-on tester indicates not just the resistance of the rod, but of the
connection to the system neutral and all bonding connections between
the neutral and the rod.
Note that in Fig. 22 there
is both a butt plate and a
ground rod. In this type
of circuit, it is necessary
to place the instrument
above the bond so that
both grounds are includ-
ed in the test. For future
reference, note the date,
ohms reading, current
reading and pole number.
Replace any molding you
may have removed from
the conductor.
Ground Resistance Tester Models 3710/3730
Ground level
Figure 22
Grounding
conductor
Ground
Utility
rod
pole
Butt plate
23