Operating instructions for Cable Detector, article 37270766
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5.2.4 Locating deeply covered power cables
In two-pole use the search depth is severely limited if the ring conductor consists of centre wires as in multi-
strand cables (such as NYM 3x1.5 mm²), because the short distance between the supply line and the ring
conductor generates a highly distorted magnetic field. A sufficiently strong magnetic field cannot be established
at the narrow places. If a separate ring conductor is used, the problem can be solved simply, since the separate
conductor can spread out the magnetic field more. The ring conductor can be some kind of conductive wires or
wire rolls. The important thing is that the interval between supply line and ring conductor be greater than the
depth at which the cable is laid. In practice this interval is usually 2 m or more.
Requirements:
The circuit must be voltage-free.
Connect the transmitter as shown in Fig. 3-2-4.
The interval between supply line and ring conductor must be at least 2~2.5 m.
The measurement procedure is the same as shown in the example.
1.
In this application, moisture or mortar in the wall has no influence down to the search depth.
2.
The stronger the signals shown on the receiver display while searching the circuit, the closer the cable.
3.
Adjust the transmitter power to suit the different search radii.
4.
Set the receiver to manual mode and set the right sensitivity to precisely locate the circuit.