Cable Locating Techniques
• Induction: The most common method for locating target utilities, allowing for the identification of each line separately.
• Signal Coupling: A common location problem, leading to errors in the marked position and depth of the target line.
• Nulling utilities: Using signal and ground connections to null utilities and interference from services.
• Ground Return: Manhole covers can be used as a ground return when locating on hard ground.
• Direct Connection: Direct connection to a metal street-lamp column is almost as effective as connecting to the cable sheath.
• Good Ground Point: Crucial when using a direct connection, providing the lowest resistance ground path and the best output signal.
• Double-ended Connections: Useful for positively tracing and identifying a target line in heavily congested industrial sites, provided there are access points at each end of the line.
• Ideal for positive identification of a target line, as the same level of current should be detectable around the circuit.