Above Telephone Space; General Measurement Notes - AEMC 3711 User Manual

Above Telephone Space

Select the current range "A." Clamp onto the ground wire and measure
the current (Fig. 31). The maximum current range is 30A. If the ground
current exceeds 5A, resistance measurements are not possible. Do not
proceed further with the measurement. Remove the clamp-on tester from
the circuit, noting the location for attention, and continue to the next test
location.
After noting the current, select the ground resistance range "Ω" and
measure the resistance directly.
The reading you measure with
the 3711/3731
bonding connections between the
Telephone ground and the Power
company ground. One of the
following two scenarios should be
observed:
A. If "OL" or a high resistance
reading is
would indicate no bond has
been established or a poor
connection exists between
the Telephone and Power
grounds.
B. If and/or a very low
reading is displayed then the
bond between
grounds has been verified.

General Measurement Notes

A reading of OL is most likely a cable which is not connected to the
ground at both ends. It may be there is no ground rod at all, or that there
is no path back to the system neutral.
A reading which is < 0.1Ω
you are clamped is continuous with itself. You may have located a
ground loop, which can usually be confirmed by comparatively high
current readings also obtained when readings are taken at multiple
locations. A good low resistance ground may also have very high AC
current flowing, depending upon the type of equipment being grounded.
Ground Resistance Tester Models 3711 and 3731
indicates the
displayed this
these two
.1
generally indicates that the cable where
taples
Ground wire doubled
under ground clamp
- 31 -
Figure 31