Greenlee BLL-200 Manuel D'instructions page 16

Operation (cont'd)
Tracing Branches from a Main Circuit
If tracing branches off a main circuit, use
the Inductive Mode and two operators. The
first operator places the receiver over the
main. The second operator carries the
transmitter, held parallel to the main,
approximately 2 meters (6 feet) from the
main circuit. An increase in signal strength
at the receiver indicates that the transmit-
ter is over a branch.
Overcoming Interference from Nearby Conductors
The transmitter's signal may be coupled to and conducted by other electrical lines, rebar
(reinforcement bar), and other conductive materials, especially where such objects are close
together. To prevent false readings under such circumstances:
• Change the transmitter to a more effective coupling mode.
• Change the coupling point. If possible, determine the endpoints of the branches. Begin
tracing from the endpoint toward the crowded area.
• Change the grounding point.
• The transmitter leads may be located too close to some of the buried conductors, allowing
the signal to couple. To reduce or eliminate this coupling:
– Reposition the leads. If possible, support them with a toolbox or other item so they do
not lie directly on the ground.
– If using the ground stake, move it to another location. If the general direction of the
buried line is known, locate the ground stake so that the extension lead runs perpen-
dicular to the buried line.
• If using the inductive mode, rotate the transmitter a few degrees.
Tracing Conductors in Concrete
Large amounts of rebar (reinforcement bar) will make this task very difficult, due to the high
amount of interference. However, it should be possible to determine where the conduit enters
and exits the slab.
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Transmitter
Receiver