SirSydom
2016-03-30 09:13:04
- #1
Oh yes – and equipped under the BP with a foundation earth electrode, as is usually only prescribed for special sealing – commonly from the white tank onwards.
That is not entirely correct.
The correct fact is that with a white tank, a separate ring earth electrode is definitely required. However, this does not replace the equipotential bonding INSIDE the foundation slab.
A separate ring earth electrode is also required if an "increased earth transition resistance" is to be expected.
A ring earth electrode is definitely not installed UNDER the foundation slab professionally, because it is dry there.
A ring earth electrode is regularly required because hardly any foundation slab gets by without a capillary-breaking gravel base with a blinding layer and often with insulation underneath the foundation slab.
Attention: there is still a lot of sloppiness in the area of grounding. Such an earth electrode may only be installed by a qualified electrician – this is regularly disregarded by shell builders.
There are also documentation obligations, e.g., plans and photographic documentation of all connections, connectors, etc...
Below are some excerpts from DIN18014
3.4
Foundation earth electrode
Conductive part embedded as a closed ring in the concrete of a building foundation
3.5
Ring earth electrode
Conductive part embedded as a closed ring in the soil outside a building foundation
Note 1 to the term: The ring earth electrode is referred to in DIN VDE 0100-540 (VDE 0100-540) as “foundation earth electrode installed in soil.”
[...]
According to this standard, a foundation earth electrode is an earth electrode embedded in concrete. If a concrete foundation is constructed with an increased earth transition resistance for structural reasons, the foundation earth electrode must be installed in the soil, then it is referred to as a ring earth electrode.
[...]
If a ring earth electrode is installed outside the building foundation, an additional functional equipotential bonding conductor for potential control inside the building foundations is necessary.
[...]
5.3 Ring earth electrode
The ring earth electrode must be installed in direct contact with the earth outside the foundations.
To achieve a constant, low earth spreading resistance, the ring earth electrode must be arranged in the moist, frost-free zone outside the foundation in direct contact with the earth.
NOTE This must be especially considered, for example, with large roof overhangs.
Installation examples:
laterally in the working space of the excavation pit, possibly below a drainage layer (see Figure 5 a), or
below the foundation in the area of the exterior walls (see Figure 5b) or
outside a frost protection apron (see Figure 5c).
[...]
5.7 Foundations with increased earth transition resistance
5.7.1 General
If the necessary earth contact of the earth electrode in the foundation is not given, e.g., due to the use of:
watertight concrete according to DIN EN 206 and DIN 1045-2 (white tank), see Figure 9;
bitumen seals (black tank), e.g., bitumen sheets, plastic-modified bitumen thick coating (KMB), see Figure 10;
impact-resistant plastic sheets;
thermal insulation (perimeter insulation) on the underside and sidewalls of the foundations, see Figure 11;
additionally introduced capillary-breaking, poorly electrically conductive soil layers, e.g., from recycled material,
a ring earth electrode must be installed.