Ground Resistance Tester Models 3711 and 3731
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Phone Pedestal
Provide sufficient room for the Model 3711/3731 jaws, which must be
able to close easily around the conductor (Fig. 29). The jaws can be
placed around the ground rod itself.
Note: If not enough room is available for this task refer to Fig. 30 and
continue with this example. The clamp must be placed so that the jaws
are in an electrical path from the sheath bond(s) or ground bar to the
ground rod(s) as the circuit provides.
Select the current range “A.” Clamp onto the ground conductor and
measure the ground current. The maximum current range is 30A. If the
ground current exceeds 5A, ground resistance measurements are not
possible. Do not proceed further with the measurement. Remove the
clamp-on tester 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
3711/3731 indicates the resistance of not just the rod, but also the
connection to the sheath ground and all bonding connections between
the sheath bond and the rod.
A high reading indicates one or more of the following:
A. Poor ground rod
B. Open ground conductor
C. High resistance bonds on the rod or splices on the conductor. Also
look for bad connections on the ground bar to the sheath(s).
Note: This same test can be done using the TIP instead of the sheath
ground. However keep in mind that this is intended to be grounded only
back at the central office.
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