Which of the following can cause an increase in signal tone when locating buried metallic conductors?

• A. Decrease in pipe depth
• B. Insulated fitting
• C. Increase in pipe size
• D. Increase in mass of metal (valve)

Answer: (D)

When a locator energizes a buried metallic path, the strength of the tone depends on how well the transmitter’s signal is coupled into the metal. More metal mass at the contact point means a larger conductive surface to carry the signal, which improves coupling and reduces energy lost to surrounding soil. That stronger coupling produces a clearer, louder tone on the receiver. An insulated fitting blocks signal transfer and dampens the tone, and changing pipe depth or pipe size doesn’t enhance coupling as reliably as adding metal mass does. So a valve or other increased metal mass near the line increases the signal tone.