7 Tracing Techniques and Helpful Information
Tracing Techniques and Helpful Information
Many variables affect the process of locating a pipe or cable. The following information
gives guidelines for various problem situations.
7.1 Soil Conditions
Generally, the effect of soil types on line tracing is minimal. It should be possible to
locate utilities in all soil types. However, soil conditions will affect the efficiency of
grounding. It is essential to create good grounding to ensure efficient signal transfer to
the target line.
7.2 Adjacent Conductors
If the field strength reading drops off more on one side of a conductor than it does on
the other, the Receiver may be picking up interference from an adjacent or parallel
conductor. Confirm the exact location of the adjacent conductors. Place your ground
lead so that it does not cross over any adjacent conductors, but is as far away from
your target conductor as possible, and is extended perpendicular to the direction in
which you are tracing.
7.3 Signal Clamp: Ground Requirements
If you are using the signal clamp around a cable, both ends of the target conductor
must be grounded to insure sufficient field strength. Power lines and telephone
sheaths are assumed to be grounded.
If the conductor is a pipe which had an insulated joint, such as a gas pipe with a meter,
use the jumper cable. Attach each end of the jumper cable on opposite sides of the
insulator.
7.4 Grounding: Safety
If you use the Direct Connect method, be sure that there is no power flowing through
the target conductor. If you use the signal clamp on energized lines, follow established
safety procedures.
7.5 Distribution Systems
To locate gas services on a gas distribution system, you must be sure that the service
is grounded. This can be accomplished by temporarily connecting a jumper cable to a
ground spike at the end of a service, where the pipe comes out of the earth.
7.6 Deep Conductor
Signals picked up by the Receiver from deep buried cables are weaker and not as
directional distinct as those from cables closer to the surface. The meter reading will
only change by small increments in relation to moving the Receiver antenna.
Using the Inductive (indirect) Method of coupling signal to the conductor may be
difficult if the target conductor is buried three feet or more, or is set in recent backfill.
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