In Conductive Mode, where should the grounding rod NOT be placed?

• A. Near a big metal structure
• B. At the transmitter location
• C. Next to the pipe
• D. In damp location

Answer: (A)

In conductive mode, the grounding rod provides the return path for the current injected by the transmitter into the ground along the target line. The goal is to have a clean, predictable path for current back to the source so the location signal can be read accurately.

Placing the grounding rod near a big metal structure is problematic because that structure presents a low-impedance path for the current. The current can preferentially flow into and around the metal structure rather than through the ground near the line, which distorts the current distribution and makes it harder to interpret the signals from the line under test. This shunting effect undermines the accuracy of the conductive mode measurement.

The other options are generally acceptable: placing the rod at the transmitter location helps complete the circuit; placing it next to the pipe supports the coupling to the target; and locating it in damp soil improves ground conductivity, all of which aid in obtaining a stable, detectable signal. Therefore, the rod should not be placed near a big metal structure.