Underground Locating

This category of products covers everything necessary to locate and trace the path of wires, cables, pipes, and conduit whether buried underground or behind walls. When looking to dig underground and avoid cutting through buried utilities, this section contains a combination of locators and tracers to allow the user to identify and mark routes and locations to save thousands of dollars in repair costs.

Cable Locator Function

Most buried utility locators function in the same fashion. Transmitters are used to energize a metallic line  (Cable or Pipe) with a frequency by direct conductive connection to the metallic line. A single lead of the transmitter is connected to the pipe. The other lead is grounded perpendicular to the line and as far from the line as possible. This creates a closed circuit, which allows current to flow. The current flowing through the pipe produces a magnetic field which forms a cylindrical shape around the pipe and represents the signal. The magnetic field is produced by current flowing and not by voltage. Capacitance increases with conductor surface area, and as a result, the larger the conductor or pipe, the shorter the distance the signal will be carried.

Why Use Different Frequencies?

Selecting a frequency is an important component of effective and successful pipe location and tracing. There is no one frequency that serves all purposes. A low frequency such as 512Hz allows tracing metal conductors over long distances (due to the long wavelength) and has little 'bleed-over' to adjacent utilities. A mid-range frequency such as 9.5KHz is a more general purpose solution as the magnetic field is stronger, but still avoids most 'bleed-over'. Higher frequencies increase the current flow, which results in a stronger magnetic field and a stronger signal as a result. A fequency of 38KHz generates a strong magnetic field, but does tend to bleed over in congested areas (at the same time allowing the signal to move across flanges and high resistance pipe joints from section to section of pipe). Best used on short distance tracing applications. Very high frequencies such as 80KHz are used on poor conductors and metal services where grounding is limited. It can also be used to locate faults in electrical services, street lighting, telephone, and CATV sheaths.