Transmission Towers; Central Office Locations - AEMC 3711 User Manual

Transmission Towers

Observe all safety requirements - Dangerously high voltage may
be present!
Locate the ground conductor at the base of the tower. Many different
configurations exist. Care should be taken when searching for the
ground conductor. Fig. 27 shows a single leg mounted on a concrete pad
with an external ground conductor. The point at which you clamp the
instrument should be above all splices and connections which allow for
multiple rods, butt wraps, or butt plates.
Note: Current flowing to ground may be high.

Central Office Locations

The main ground conductor from a ground window or a ground plane is
usually the location to clamp the tester. Due to the wiring practices within
the central office, there are many locations at which you can look at the
water pipe or counterpoise from within the building. An effective location
is usually at the ground buss in the power room, or near the backup
generator.
By measuring current and resistance at several points and comparing
the readings, you will be able to identify neutral loops, utility grounds and
central office grounds. The test is effective and accurate when the
ground window is connected to the utility ground at only one point.
Ground Resistance Tester Models 3711 and 3731
Support
round Rod
Figure 27
- 27 -
Concrete
Pad