Page 45 - CCGA Best Practices Version English

same trench should be individually marked and identified. In situations where
two facilities share the same colour code (such as telephone and CATV) both
facilities should be identified and the marks placed parallel, but with enough
separation so that they may be readily identified. In circumstances where the
total number of lines buried in the same trench by a single owner may not
be readily known, a corridor marker is used. The corridor mark indicates the
width of the facility.

3-11: Locate Method Preference

Practice Statement: When locating electro-magnetically, active/conductive
locating is preferable to passive/inductive locating.

Practice Description: The preferred method of actively applying a signal
onto a facility is to use direct connection. Direct connection is the process
of connecting a direct lead from the transmitter to the target facility and
connecting a ground lead from the transmitter to a ground point in order to
complete a circuit. This process provides the strongest signal on the line and
is less likely to spill to adjacent facilities than other methods of applying a
signal. This method allows a greater range of frequency and power output
options. It is good practice to use the lowest frequency possible at the
lowest power output possible to complete the locate. If direct connection
is not possible, use of an induction clamp (coupler) is the most effective
method of applying a locate signal onto the target conductor. This method
is more limiting for the choices of frequency and power outputs than direct
connection. Using an induction clamp is not as effective at transmitting a
signal as direct connection, can only be used within certain frequency ranges,
and must use a higher power output. The least preferred method is induction
or broadcast mode on a transmitter. This usually results in a weak signal that
will spill to any conductor in the area.
When using any of the above three methods, the locator should trace the
entire line from the point of signal application through the proposed work
area.

Origin/Rational
It is very important that locators do not apply a signal application to a line,
walk out to the work area and begin locating. This can lead to picking up
signal on facilities other than the target line. Tracing continuously from the
point of signal application to the end of the work area improves the accuracy
of the locate.

Notable exceptions may include utility "Transmission" situations, where
signal application opportunities may be limited (e.g. fiber optic networks,
transmission pipelines and long distance power conductors). In these
situations, to ensure that a reliable locate is achieved, attention should be
paid to ensure a suitable signal launch is achieved. Subsequently, careful
reference to distant locate signal characteristics should be made.

Canadian Common Ground Alliance
Best Practices Version 3.0 – October 2018
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