24
Soil Type
Effect on Line Tracing
moist, compact
ideal
dry, sandy, or rocky
little or no moisture content
creates a poor tracing
environment
alkaline, high iron content
poor tracing environment
5.2 Field Strength of the Signal
When the signal is applied to the conductor using any of the three "Active" methods covered in Section 4.1
- 4.3, an electromagnetic field is created around the conductor. The receiver measures the strength of this
field, displaying it on the field strength meter.
The field strength decreases as you move away from the target conductor and as you move farther away
from the transmitter (in the "Active" mode). For optimum tracing accuracy, the field strength should read
at least 5 on the meter at maximum gain.
5.3 Verifying Versus Tracing
Verifying means to confirm that a conductor if present, and tracing means to map out its route along the
ground. Besides its use for locating a able, the 480B’s 50/60Hz power line locating mode is also helpful
for determining the presence of energizing power lines and other conductors. The active range using the
Transmitter generally produces the best accuracy when tracing.
5.4 Adjacent Conductors
When the meter reading drops off more on one side of the conductor than it does on the other, the Receiver
may be picking up interference from an adjacent or parallel conductor. Adjust the sensitivity to compare
the signal strength of the conductors. In most cases, the conductor with the stronger signal is the target
conductor. If you are using the Active Mode, confirm the exact location of the adjacent conductors. Place
your ground lead so that it does not cross over any adjacent conductors, is perpendicular to, but as far away
from your target conductor as possible.
Note evidence of other underground utilities in the area, such as transformers, pedestals, hydrants, meters,
etc. which indicate the presence of other underground conductors.
5.5 Deep Conductor
Signals picked up by the receiver from deep buried pipes are weaker and not as directionally distinct as
those from pipes closer to the surface. In addition, 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 four feet or more. For best results, use the Direct (Conductive) Connection method of
coupling signal to the targeted conductor.
5.6 Tracing Long Runs