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7.4 Terrain
examination
To examine a particular area for existing cable/pipes systems we recommend the following
procedure:
-
Divide the area in question into squares of approx. 25 x 25 m.
-
Set up the Audio Frequency Generator in the centre of the cable run.
-
Set ground rods into the ground to the left and right of the generator at approx. 12 to
15m.
-
Keep output power of generator low.
If there is a metallic conductor within the set out area, it will propagate a magnetic field in its
vicinity. The magnetic field has in most cases the shape of a single-sided maximum; e.g. with
a steep edge to the audio frequency waveform.
7.5 Cable
identification
As this method requires a high technical knowledge for cable identification, the use of a the
special instrument KSG 100 is recommended. To prevent possible accidents due to
inappropriate handling or misinterpretation of the cable selection, it is generally
recommended to use cable cutters according to EN 50340 and/or a cable shooting devices.
The local safety and accident precaution instructions are always applicable, and mandatory.
If a cable is to be picked out of several in a cable duct (e.g., cutting for a house connection):
- disconnect the desired cable at all end points
-
sheath remains grounded
-
connect two wires with each other at one end point
-
connect Audio Frequency Generator across 2 short-circuit wires and set current to 0.1
to 0.5 A.
Summary of Contents for TG 20/50
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