11 Resistance symmetry (RSym)
56
ARGUS Copper Box
Special features for RE (Examples):
1a. Measuring site, e. g. demarcation point:
The demarcation point is not earthed. The
Copper box (GND socket) is disconnected
from the shielding terminal of the demarca-
tion point. The measurement works when
the cbale shield os continuous. The dis-
played RE measurement is the R-cable
shield (Rshield). The measurement works
even if e. g. a shield terminal in the earth
cable becomes high-ohm due to an installa-
tion error or a lightning strike. This can then
be recognised from the high RE measured
value.
1b.However, if the cable shield is not contin-
uous (see image) or too high-ohm, the mea-
surement will no longer function
(RE>10 kΩ).
As a remedy, the reistance symmetry mea-
surement can be conducted using the build-
ing potential equalisation rail or an earthed
metal water or heating pipe. If this is not pos-
sible either, trained electricians can, after
checking the building configuration (TN-S,
TT), use the PE (protective ground) line as
an earthing point after verifying thar it is
voltage-free. In general, attention must be paid to ensuring secure contact, particularly to
oxidised or corroded earthing points.
The measurement does not work when the earthing is interrupted at one of the connection
points. However, it will work for a poor ground connection. Reason for cancellation of mea-
surement (RE >10 kΩ).
