3 Copper tests
26
ARGUS Copper Test Manual
2. Measuring site, e. g. demarcation point:
The demarcation point is not earthed. The cable shield is interrupted at the site shown in
the illustration. However, the resistance symmetry measurement can still work if the cable
shield at the demarcation point is connected to one of the earthing points shown in the pic-
ture. However, the RE measurement is not Rshield, as the shield can have an ground
potential of varying quality due to the lead sleeve in the ground (obsolete construction
method). The ground potential can also come from a network of building accesses (other
earthed demarcation points) in the branch cable: In the main cable area, the ground poten-
tial can come from another cable branch box. In practice, a combination of the two exam-
ples is quite common. All these effects lead to varying RE measurements.
3. TAE (residence)
Resistance symmetry is often faulty in the last mile, e. g. due to a poor splice (rat-tail splice,
poorly crimped conductor connections, loose screw connection).
A measurement is possible if the last mile is a connected to a buried, continuous shield
conductor this case is not illistrated). However, This is seldom the case. Thus, you must
either lay an auxiliary conductor, e. g. from the potential equalistion point to the
measurement, or use earthed harting pipes in the residence.
If does not work, trained electricians can, after checking the bulidung mains configuration
(TN-S, TT), use the PE (protective ground) line as an earthing point after verifying that it
voltage-free. In general, attention must be paid to ensuring secure contact, particulary to
osidised or corroded earthing points.
