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the building. These narrow gaps or ducts can occur during the
curing process and the resulting shrinkage of concrete.
Therefore, professional and proper installation of the wall
bushing into the formwork is essential. This is described in de-
tail in the relevant installation instructions.
Waterproof wall bushings for “white tanks”, e.g. Part No.
478 550 (Figure 5.5.2.17):
¨ Version for installation into the formwork with water bar-
rier and M10/12 double thread on both ends is connected
e.g. to a ring earth electrode or equipotential bonding bar.
¨ Adjustable depending on the wall thickness by means of
M10 thread and lock nut. The thread of the bushing can be
5.5.2.15 5.5.2.16 shortened, if required.
Figure 5.5.2.15 Wall bushing installed in the formwork ¨ Tested with compressed air of 5 bars according to
Figure 5.5.2.16 Test setup (sectional view) with connection for the IEC 62561-5 (EN 62561-5)
pressure water test
“Black tank”
The term “black tank” refers to the black multi-layer bitumi-
nous coating applied to the building in the soil to seal the
building. The building structure is covered with a bitumen /
tar mass over which typically up to three layers of bituminous
sheetings are applied (Figure 5.5.2.18). Nowadays, a poly-
mer-modified bituminous coating is also used.
Due to the high insulation values of the materials used, it can-
not be ensured that a foundation earth electrode is in contact
with the soil. Here again, a ring earth electrode in conjunction
with a functional equipotential bonding conductor is required
(same procedure as for “white tanks”).
Wherever practical, the external ring earth electrode should be
led into the building above the building sealing, in other words
Figure 5.5.2.17 Waterproof wall bushing above the highest ground water level, to ensure that the tank
is waterproof in the long term (Figure 5.5.2.19). Pressure-
water-tight penetration of the concrete is only possible by
means of special components.
Perimeter insulation
Nowadays, various types of foundations with different designs
and sealing versions are used.
Heat insulation regulations have also influenced the design
of strip foundations and foundation slabs. If foundation earth
electrodes are installed in new structures based on the Ger-
man DIN 18014 standard, the sealing / insulation has an effect
on their installation and arrangement. Perimeter refers to the
wall and floor area of a building that is in contact with the soil.
Perimeter insulation is the heat insulation fitted around the
building. The perimeter insulation situated outside on the seal-
Figure 5.5.2.18 Bituminous sheetings used as sealing material ing layer encloses the building structure without forming heat
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