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9.5 Estimating the Depth of a Conductor
Follow this procedure to estimate the depth of a buried conductor:
1 Using the NULL method, find the exact location of the conductor. At a minimum distance
of 35 feet from the transmitter (to prevent air coupling between the transmitter and receiver),
locate and mark the conductor.
2 Then, still in the same mode of operation (NULL), tilt the Receiver to 45 degrees (aligning
the bubble), and move off to the side of the conductor. See Figure 4-5.
Figure 9-5: Estimating the Depth of a Conductor
3 When you "locate" the conductor a second time, with the Receiver at a 45 degree angle,
mark the spot on the ground. The distance between this second spot and the true location
of the conductor (A), less the distance between the center of the Receiver and the ground
(B), is equal to the depth of the conductor (C). See Figure 9-5.
4 Measurement accuracy is affected by the ratio of the conductor diameter compared to how
deep the conductor is buried. (The larger the pipe the less accurate the depth
measurement.) Depth measurements are also affected by soil conditions, overhead lines,
and adjacent conductors.
