© 2014 Radiodetection Ltd
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Section 7 - General Locating tips
7.1 Eliminating services
7.1.1 Induction
If several conductors are running parallel and it is not
possible to connect a transmitter, each line may be
located separately. Proceed as follows:
1 Perform a sweep of the area to find the position and
number of conductors in the area.
2 Map the direction in which the conductors are going.
To trace the lines:
1 Select induction mode on the transmitter.
2 Select the same frequency as on the locator.
3 Place the transmitter on its side and in line with a
conductor
4 Ensure the conductor is directly below the
transmitter
5 This will null the signal directly below the transmitter
and, in addition, enable the other conductors to be
located
6 Locate each conductor and mark its position
7 Move the transmitter down the route and continue
locating and marking.
8 Trace each conductor out of the search area until
the target can be accurately located.
7.1.2 Unwanted signal coupling
Unwanted coupling of the signal from the target line to
another nearby line is one of the most common location
problems. It leads either to an error in the marked
position and depth of the target line or to marking the
wrong line. A certain degree of coupling is unavoidable
in many situations but there are ways in which a careful
user can reduce coupling and increase location
reliability.
Avoid applying the signal by induction. The
signal may be coupling to more than one
line directly from the transmitter. Use the
signal clamp where possible.
Identify points where lines may be bonded
or in close proximity to each other. Work
toward these points rather than away from
them. For example, if gas and water pipes
are bonded within a building, apply the
signal at the valves or access points in the
road rather than in the building.
Reduce coupling to a parallel line by using
a low signal frequency where available
Return signal flowing on another line. Use a
double-ended connection to by-pass the
ground return if possible
Choose a signal application point where the
line is furthest from other lines and not in a
congested area
When using single-ended connection, site
the ground stake as far from the target line
as possible and away from other buried
lines
Figures 7.1
– 7.4: Interference from services
Summary of Contents for rd7000+
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