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SeekTech SR-60
When the fields are simple and undistorted, then the informa-
tion from sensed fields is representative of the buried object.
If those fields are distorted and there are multiple interacting
fields, it will cause the SR-60 to locate inaccurately. Locating is
not an exact science. It does require the operator to use judg-
ment and look for all the information available beyond what the
instrument readings may be. The SR-60 will give the user more
information, but it is up to the operator to interpret that informa-
tion correctly. No locator manufacturer will claim that an opera-
tor should follow the information from their instrument exclu-
sively. A wise operator treats the information gained as a partial
solution to the problem of locating and combines it with knowl-
edge of the environment, utilities practices, visual observation,
and familiarity with the instrument to arrive at an informed
conclusion.
Locating accuracy should not be assumed under the following
conditions:
1.
When other cables or utilities are present.
may produce distorted fields and illuminate cables or pipes
unintentionally. Use lower frequencies when possible and
if possible eliminate connections between the two cables
(such as common bonding to ground).
Figure 68: Bleed-over
2.
When tees, turns, or splits are present in the line.
following a clear signal that suddenly becomes ambiguous,
try seeking in a circle of about 20' around the last known
point to see whether the signal picks up again. This may
reveal a branch, joint, or some other change in the line. Be
alert to "split opportunities" or sudden changes of direction
in the utility being traced. Turns or tees can cause a sudden
increase in the Distortion Indicator response.
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3.
When Signal Strength is low.
for accurate locating. A weak signal can be improved by
changing the grounding of the circuit, frequency, or trans-
mitter connection. Worn or damaged insulation, bare-con-
centric cables, and iron pipes exposed to ground will com-
promise Signal Strength through leakage to ground.
4.
Far-end grounding
ly. Where far-end grounding cannot be established a higher
frequency will provide a stronger signal. Improving ground
conditions for the locating circuit is a primary remedy to a
poor signal.
5.
When soil conditions vary.
very dry or water-saturated, may affect measurements.
For example, ground that is saturated with salty water will
shield the signal severely and be very difficult to locate in,
especially at high frequencies. In contrast, adding water to
very dry soil around a ground stake can make a major im-
provement in signal.
"Bleed over"
6.
In the presence of large metal objects.
past a parked car during a trace, for example, can cause an
unexpected increase or decrease in Signal Strength, which
will revert to normal when past the distorting object. This
effect is stronger at high frequencies, which "couple" more
readily onto other objects.
The SR-60 cannot change the underlying conditions of a difficult
locate, but changing frequency, grounding conditions, transmit-
ter location, or isolating the target line from a common ground
can change the results, by making a better ground connection,
avoiding signal splits, or reducing distortion. Other locating re-
ceivers will give an indication that they may be over the line but
they have less ability to determine the quality of the locate.
The SR-60 provides more information. If all of the indicators are
aligned and in agreement, mark-outs can be made with more
confidence. If the field is distorted it shows immediately. This
allows the operator to do something to isolate the target line,
change the grounding, connection point, move the transmitter,
or change the frequency to get better reception with less distor-
tion. For extra certainty, take steps to inspect the situation, such
as by requesting potholing.
When
In the final analysis, there is one "most important" component
in the locating task – the operator. The SR-60 provides an un-
precedented amount of information to be able to make the cor-
rect decision rapidly and accurately.
Ridge Tool Company
A strong signal is necessary
will change Signal Strength significant-
Extremes in moisture, either
Simply walking
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