Verify The Fault; Advanced Techniques; Faults Under Inaccessible Surfaces - Amprobe A-5000 Mode D'emploi

4. When the arrow changes direction, back track. Check the "Active" LCD number and compare it to the "Reference" LCD
number. If both active and reference numbers have the same or similar value, you have found the major fault.
5. Insert the A-Frame every 2' (50 cm) until the arrow changes direction again, then turn it 90 degrees. Check for obvious causes
where a fault is suspected, such as recent excavation.
6. Continue to move the A-Frame across the cable until a slight movement causes the arrow to change directions. When this
happens, the fault is located at the center of the A-Frame.

verify the Fault

1. Move slightly off to one side of the cable.
2. Insert the A-Frame into the ground at various positions around the suspected fault site (like the hands of a clock).
3. The arrow should always point toward the fault.
4. Place the other spike in the ground at the fault site and repeat the process. The arrow should always point inward, toward
the fault. See Figure 7-2.

AdvANCEd tEChNIQUES

Faults Under Inaccessible Surfaces

When the faults exist beneath a paved or other inaccessible area, the fault may be located using one of the following methods.
Perpendicular Method
Carefully trace the location of the faulty conductor. Hold the A-5000 parallel to the cable path. As you move away from the
ground rod the bar graph and the active number will gradually decrease until reaching the midpoint. It will then increase until
reaching the fault. When the A-Frame center passes a line perpendicular to the Sheath fault, the directional arrow indicators
will rapidly change positions and the bar graph and active number will drop to zero. See Figure 8-1.
Paved Surface
Triangulation Method
As shown in Figure 8-2, (the point where the signal strength is a minimum) if the A-5000 is positioned exactly on an
equipotential circle, a perpendicular line from the center of the A-Frame will pass through the fault. The intersection of any two
such perpendicular lines defines the fault location.
Figure 7-2: Fault Confirmation
Cable Fault
Figure 8-1: Perpendicular Method
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