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When tracing a long line, the strength of the signal will diminish as you move
further from the exciter, until it is no longer strong enough to complete the
trace. This can be overcome by “leapfrogging”. Select a point on the line that
still has a clear signal and the direction of the line is well defined. Move back up
the line (toward where you started) about 20 feet. Place the BuzzBox over this
spot, with the “tracks” set parallel to the direction of the line, and use Inductive
mode (regardless of the mode you originally used to get this far). Now continue
the trace further along the line; you should find good signal for a good distance.
If you run out of signal again, do another “leapfrog”.
Power Line Tracing Considerations
You should plan to use the Power mode on the receiver only for initial survey
of an area to detect the presence of underground power lines. Remember that
this mode is only effective if there is considerable power being drawn through
the underground lines; the signal from a light residential load probably can’t be
detected this way. Basically, if you detect a signal using Power mode you can
be fairly confident there is underground power nearby, but the lack of signal is
no guarantee that underground power does not exist in the area.
See the section titled “Power Mode” under Getting to Know your Tools for
details on using Peak Power and Null Power screens for detecting and tracing
underground power using passive techniques.
The best method to use for precise power line tracing is the Inductive mode,
using the BuzzBox, as described earlier. Usually the higher frequencies (32
kHz and 64 kHz) work best for this. If you have indications from Power mode
that there is underground power in the area, but can’t find a conduit riser on
a building or pole nearby to initiate an Inductive locate from, you may have
success by using the following method: Determine as best you can the route
of the underground power, set the BuzzBox to 32 kHz or 64 kHz and lay it on
the ground so that the Tracks are parallel to this route, then use the LF2200 at
the same frequency to trace the induced signal. If you can trace a clear and
repeatable path this way (further than 15 feet from the BuzzBox), you can be
reasonably sure you have located and traced an underground line. Whether
this is a power line or some other underground metallic line is not certain,
unless you can trace it to an identifiable source of power like a conduit riser.
Remember these things about using Power mode:
• The highest reading when using Peak Power screen will occur when the
LF2200 is at right angles to the direction of the line, directly above it.
• When using the Null Power screen, the handle vibration and solid track lines
also occur when the LF2200 is in line with the direction of the line. (Note that
this is not the way the LF2100 works on this screen.)
• Automatic depth readings is not available in Power mode.
• The presence of signal in Power mode is very dependent on the power
being drawn through the buried line. Be prepared for the signal to suddenly
disappear if the load on the line is decreased.
• Test for field distortion by lifting the LF2200 when you have located the line
using the Null Power screen. If the apparent location moves to the right or
left as you raise it, the field is distorted and you should use the Peak Power
screen to establish the correct location of the line.
The LF2200 Menu
Top to bottom, this is what each choice in the LF2200 menu offers you:
These are preset sonde frequencies that the
LF2200 will locate. The frequency you select here
must match the frequency of the sonde you are
going to use.
These are preset line tracing frequencies, for use
in conjunction with a line exciter like the Prototek
Blue BuzzBox. The frequency you select here must
match the frequency that is set on your line exciter.
This is the selection for passively detecting the
presence of underground power. This can be set to
50 or 60 Hz using the Power menu item (below) to
match the frequency of power in your area.
The LF2200 will “sniff” the frequency of any
operating sonde, from 16 Hz to 100 kHz. Two
custom frequencies can be set and saved.
The LF2200 will also “sniff” the frequency of any
operating line exciter between 16 Hz and 100 kHz,
and save two custom frequencies. Details on how
to use sniffing are on page 17.
The bottom three menu items are “toggles”, which means you can switch
between two options by clicking the button to the right. Doing this only
changes the item you are on, and leaves you in the menu.
When you select “audio” and click to the right, the
speaker is turned off or on, toggling to the opposite
of how it was set before. The upper picture here
represents speaker “on”, the lower is “off”.
Toggle between displaying depth in Feet/inches or
Meters/decimeters by pushing the button to the
right.
Set this to match the frequency of power in your
locality, so that the LF2200 can pick it up in Power
mode. Whatever this is set to will be reflected in
the Power menu item (above).
The last two items generally only need to be set once, to match your local
conditions, and never touched again. In most cases, it will have been set to
your locality already by Prototek.
The audio setting can be modified at will whenever you desire. This setting
was provided for those who find the clicking sound during a locate distracting,
or disruptive to others in the area. The speaker is also turned off any time
you have headphones plugged in; in that case only the operator who is using
the headphones will hear the clicking (if audio is “on”).
