Amprobe A-5000 Sheath Fault Locator - Manual (Page 17)

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Paved Surface
Cable Fault
Figure 8-2: Triangulation Method
To find an equipotential circle (see Figure 8-3) insert the A-Frame into the ground and pivot around one spike. Rotate the
A-Frame back and forth until the exact point is found where the flashing arrows change direction. The A-Frame is now on
an equipotential circle and is perpendicular to the fault. By marking this line and repeating the process with the A-Frame at
another nearby location, the two lines will intersect or cross at the fault.
Figure 8-3: Locating an Equipotential Circle
Faults Under Pavement
Faults under pavement or other slightly conductive surfaces can be found using the foam pads supplied with the unit. Saturate
the pads with water and insert the A-Frame spikes into the pads. Locate the fault as you normally would. Be sure to keep the
pads as moist as possible, but do not let the water form a continuous puddle between the pads as this will short out the signal.
Long distance tracing
As the distance to the fault increases, the signal picked up by the A-5000 is proportionally reduced. This condition can lead to
problems if the signal levels are reduced to the point that they can no longer be detected by the A-Frame.
Whenever working with weak signals due to long distance faults (or other reasons), increased sensitivity can be obtained by
extending the distance between the A-Frame spikes using the extension cable. This extension method can be applied to any of
the previously discussed methods including the conductive foam pads. When working with very long distances, as in fiber optic
runs, the sensitivity can be increased even further using a longer insulated wire to extend the A-Frame span. See Figure 8-4.