Forgetting the foundation grounding - tips?

  • Erstellt am 2016-03-05 18:48:16

Kerstin2

2016-03-05 18:48:16
  • #1
Hello everyone, out of sheer exuberance we forgot about the [Fundamenterder]. We have been talking about the [Fundamenterder] the whole time, now the foundations are finished and the earthing is not in! Under the garage there will be a slab and under the slab of the house there will be the XPS insulation 10 cm. What would be your approach?
 

Legurit

2016-03-05 18:52:45
  • #2
When in doubt, hire someone who knows what they are doing...
 

Dipol

2016-03-10 23:36:28
  • #3
There is plenty of free downloadable secondary literature on this question, in particular the DEHN Blitzplaner, the VdB lightning protection installation manual, Kleiske Info, and also slides from me, so that everyone can inform themselves even without a VDE selection subscription or DIN 18014 and regarding the question of who is allowed to install a foundation grounding. If the frost skirt does not have full perimeter insulation, a foundation grounding conductor would have been sufficient. Since it is too late for that, one can only install a PA conductor in the insulated floor slab and a norm-compliant stainless steel ring grounding conductor (V4A) in the natural ground. A vertical grounding electrode is cheaper but not an equivalent substitute for the ring grounding electrode. Details such as mesh sizes and other implementations are exhaustively covered in the mentioned publications.
 

Landschafter1

2016-06-18 14:46:29
  • #4
Hello everyone,

We started building our house in March this year. Except for the earthworks, everything was awarded to a general contractor. He also forgot the foundation earth conductor/functional equipotential bonding for us, or rather his subcontractor forgot it... There are expert reports from both sides regarding the resulting problem.

The general contractor's expert assured me that everything was fine... Since I was skeptical, I sent it to another expert, the one mentioned above. The first thing he noticed was that the general contractor's expert had used the 2007 version of the DIN, including all tolerances and measurement values – and the measuring instrument was also not approved by the VDE... The general contractor's expert had tried to compensate for the missing foundation earth conductor and functional equipotential bonding by installing a ring earth conductor around the house and creating connections to the reinforcement of the slab at four points. The ring earth conductor itself lies at a maximum of 60 cm in the ground, in some places less than 20 cm, and even in the gravel/splint. It also does not encompass the entire structure but was pushed under the slab at one point (width in that area 2.2 m). The mesh spacing of 20*20 m was also not observed.

We presented all of this again to the general contractor and his expert, but both still claim "everything is flawless and not dangerous to life and limb."

My expert said that retrofitting the FPA as prescribed by the DIN is practically impossible or an enormous effort. He also views the ring earth conductor critically, as the mesh under the slab would also be difficult to install.
 

Dipol

2016-06-19 11:42:36
  • #5
Just one extreme example more of the usual resistance to the standard regarding DIN18014.


For execution, the nominal standard valid at the time of completion is decisive.

That the grounding system may only be installed according to NAV by licensed electrical or lightning protection specialists and must be documented before concreting is, contrary to the amendment communications of DIN 18014:2014-03, not new.

More significant is the change of the contact resistance from 1 to 0.2 ohms and the minimum installation depth, see below.


This is an emergency solution but not a full substitute for a PA conductor laid in the floor slab according to paragraph 5.7.2 Combined equipotential bonding system (CBN) of DIN 18014, which must be connected to the reinforcement every 2 m. Even if this emergency solution was implemented, I believe there is still a claim for reduction.


Ring earth electrodes installed like this, even with compliant mesh dimensions, do not conform to the generally accepted rules of technology.

The frost-free minimum installation depth of ≥ 0.5 m according to the old DIN 18014:2007-09 was adjusted in DIN 18014:2014-03 to ≥ 0.8 m to align with building standard DIN 1054 and may require even deeper installations regionally.


In the face of such gross errors, one might as well try to get ahead of it. A work is free of defects when it essentially complies with the generally accepted rules of technology (= standards), which is clearly not the case here multiple times.

Whether a danger to life or limb exists primarily depends on the earth spread resistance. How high and during which time of year was it measured? Ring earth electrodes laid continuously with earth contact certainly have better values, and according to my legal understanding, one does not have to accept sufficient but unnecessarily worse values.


The first error could only have been remedied by demolition, which, in my view, would still have been reasonable in terms of effort as long as the basement floor is not yet in place. A ring earth electrode not continuously earth-contacting around the entire house can be corrected retroactively to comply with the standard. Mesh sizes too large at 20 m x 20 m without or 10 m x 10 m with a lightning protection system can be compensated with additional vertical electrodes.
 

T21150

2016-06-19 12:07:14
  • #6
Before Roland's professional expertise, one can only take off their hat.

When building, I would have wished: Only such competent people on site.

Instead, I always had to read up myself and then target my efforts accordingly.

Respect, dear Roland, for your knowledge and your attitude towards the subject/profession.

Best regards
Thorsten
 

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