22
Figure 4-10: Adjusting for Audio Balance
Locating with the Handle-Mounted 480B
1 Holding the handle-mounted 480B with the Receiver face up and the Transmitter on the back end, start
traversing the area you need to blind search.
2 As you cross a conductor at right angles - the point of maximum audio and visual signal, make a mark
on the ground.
3 Continue to walk in the same direction until "no signal" is registered. At this point make a 180 degree
turn and walk back over the same path until the maximum signal registers on the meter and audio tone
again. Make a second mark on the ground at this point. The true location of the conductor is midway
between the two marks.
Blind Search, Metal Mass Location, Ground Survey with the Carrying Handle
A "blind search" is a search for the location of a conductor with an unknown source or ending. The 480B
must be operated in the Inductive Mode using a systematic grid approach. Looking for a "metal mass", such
as a manhole cover or steel drum is the same as a "blind search" with the exception that the search paths
need to be closer together so as not to miss the metal object. A "ground survey" is a process by which an
operator can locate all the underground conductors within a particular area.
4.8 Conductor Identification Using a Second 4820 Metroclamp
When exposed multiple conductors are present, for example in conduits, ducts, or pedestals, use the
method described below to identify a specific conductor
1 Apply transmitter signal to the target conductor using a 4820 Metroclamp, as described in Section 4.2..
2 Plug a second Metroclamp cable into the jack marked AUX INPUT on the Receiver.
3 Set the RANGE switch on the receiver to "Norm". Set the MODE switch to "Active".
4 Place the Metroclamp around each conductor in succession, making sure that the jaws are fully closed.
The conductor with the highest field strength indication is the target conductor. (Figure 4-11)