Which statement best describes high-frequency signals used in induction locating?

• A. They are easy to apply by induction; currents are stable; long travel
• B. They are easy to apply by induction; couple easily to unwanted lines; do not travel far
• C. They are difficult to apply; do not couple to adjacent lines; travel far
• D. They are not used in induction methods

Answer: (B)

High-frequency signals used in induction locating are chosen because they can be applied easily with induction methods, meaning you can energize the buried conductor without a direct long connection along the route. These signals readily couple to nearby conductors, so adjacent pipes or cables running near the target can pick up the signal even if they’re not the line you’re tracing. At the same time, soil attenuates high-frequency energy, so the signal doesn’t travel far through the ground, keeping the detectable field localized to the area around the target. That combination—easy to apply by induction, strong coupling to nearby lines, and limited travel distance—best describes how these high-frequency signals behave.