Underground Cable Locator Theory & Application

As a transmitter emits electromagnetic waves, a magnetic field is generated.If a metal pipe or a cable is laid within the magnetic field, induced current (signal current) is produced and flows through the underground metal pipe or cable according to the principle of electromagnetic induction.

Then, a receiver picks up the magnetic field generated by the subsurface metal pipe or cable.

The location and depth of the subsurface pipe or cable is located by the angle of the magnetic force concentrically generated by the metal pipe and the strength of the magnetic field.

Optional External Coil (Inductive clamp mode) available for locating Utility-line that has an insulated coating and for Power-line and Telephone-line that cannot be connected directly in the direct mode (Inject mode).

The method is to locate where the traceable rodder stops, at the conduit with other copper cables.

The issue is that the signal injected into the traceable rodder spreads to other copper cables in the conduit, which makes very hard to locate where the traceable rodder stops.

Note: due to the variation of the field condition, the user should take into the consideration of the inconsistency of the conduit buried depth, and small variation of the signal level. And move the receiver left and right till the maximum signal level is tested. The % figure may vary.

Measure the depth of an underground cable

The following method can be used to calculate the depth if the cable locator doesn't have the Depth measurement function.

  • Using the ruler to measure the a, b where the Locator reads the same value (in this case, it is the value of 2500)

  • The Depth = (a*a + b*b)/2*a