Home generalRetrofitting equipotential bonding / grounding in the house - procedure + costs

Retrofitting equipotential bonding / grounding in the house - procedure + costs

  • Task of grounding
  • The wrestler
  • The earth driver
  • Other types
  • Expiration of a foundation grounding
  • Tips for quick readers

Equipotential bonding on a house is a central component of its electrical equipment. It serves to protect the house against overstretching, short circuits and lightning strikes against the spread of electrical damage. The measure commonly referred to as "earthing" is today planned and implemented by default in house building. Due to formerly valid laws, however, numerous houses up to the 1960s are still equipped with no or only insufficient equipotential bonding. In this case, today must be retrofitted.

Who can install a grounding ">

With a lot of goodwill on the part of the electrician, it may be possible to carry out the individual work steps themselves and to lose weight. But the electrician must then come to the construction site after every step and give his OK. This can be useful if the electrician is heavily used and can not free up time for small tasks like these. Since the electricians not only earn their money with this work, but also take responsibility for it with their signature, an own contribution in this case is only very rarely enforceable.

Task of grounding

Grounding or equipotential bonding has the task of dissipating surges into the ground. For this purpose, the RCCB is connected to the equipotential bonding.


This can then be connected, with appropriate design, with the lightning rod. The installation of the foundation foundation has been mandatory for every new building since 2007. Previously, compromises were also made by using sewage pipes or other earth-bound metal pipes as grounding. However, since plastic pipes are increasingly being used for this purpose and the metal pipes have proved to be very susceptible to rusting due to the electrical stress, the conditions for earthing are particularly stringent today. In detail, process, design and permissible personnel are regulated in DIN 18014.

The wrestler

The most commonly used in new buildings earth electrode is integrated in the strip foundation or floor plate Ringerder. It consists of a long sheet of galvanized steel. It is laid on the outside in the form of a ring around the entire building and laid inwards via a connection cable with a wide cross-section. The wrestler is currently the cheapest to lay the foundation of the foundation: The wide plate is simply anchored together with the reinforcement in the formwork and concreted. With sufficient concrete cover galvanized steel is perfectly sufficient. One meter earthing strap costs about 1.30 and is mounted virtually free of cost when introducing the reinforcement.

Wrestlers can also be equipped. For this purpose, a ditch of 0.5 meters to 1 meter depth is drawn around the house. In this case, however, if you do not want concrete or can not, no galvanized sheet must be used. Although earthing strap by default has a layer of 70 microns of zinc as a minimum for corrosion protection, this is not sufficient for contact with the permanently damp soil. The tape would rust. In addition, electrical stress is also highly conducive to corrosion. That's why only the expensive V4A comes into question for a retrofitted wrestler. This stainless steel is extremely corrosion resistant and thus a permanent solution. However, this has its price: At just under 9 euros per meter, the ring anchor made of stainless steel is almost ten times as expensive as galvanized sheet steel in terms of material. In addition, there are the costs for installation and acceptance by the electrician.

In a house with 10 meters edge length and a wrestler of 0.03 meters you come to an area of ​​about 3 m² effective contact surface to the ground, from which the current to be dissipated is emitted. This large area is the default for any other Earth form.

The earth driver

A depth grounding is a popular form of ground anchor, if the structural conditions do not allow the subsequent installation of a ground anchor. It consists of a long rod, also made of V4A stainless steel. He is rammed at least nine feet deep into the ground. It must be ensured that the earth electrode can not cause damage to other installations such as power lines or sewage pipes. A preliminary ground survey is therefore required to determine the ideal impact point of the earth electrode.

Connection clamp for earth electrodes

A depth hammer costs about 20 euros per 1.5 meters rod. The rods can be inserted into each other and connect together when driving permanently together. The reaming of the earth electrode is a thing for a professional operation with appropriate tools. For smaller tasks, a strong hammer drill is sufficient. For larger foundation earth but a pile driver is needed. To set a ground anchor in a simple family home you have to calculate between 200 and 500 euros.

Other types

Basically, it only depends on an earth electrode that there is sufficient contact surface with the soil. Therefore, instead of a Tiefenerders or a ring anchor come:

  • Straight earth electrodes
  • Strahlerder
  • Plattenerder or
  • Mesh miner into consideration.

Straight earth electrodes are horizontally routed grounding straps, cables, or rods, and are placed parallel to ground power cables. They are very inexpensive, as they cause virtually no installation costs, but must already be included in the construction of the house.

In order to come to the required contact surface to the soil, the rectilinear earth can also be distributed radiant or cross-shaped. The important thing is that all the rays meet in a common point and have electrical contact there. A maximum of six individual beams are allowed, which are laid at an angle of 60 ° to each other.

If one connects the rays of a ray generator with each other, one obtains a field with six meshes. This type of earth is called mesh. In order to avoid misunderstandings: A mesh mower is definitely not a buried chain link fence! Also, only permissible material can be used for the mesh former, which has a sufficiently large cross section.

Finally, plate earthing is also permitted as ground connection of a house. They can optionally be buried horizontally at a depth of 0.5 - 1 meter and driven vertically back into the ground.

Their use is, however, reserved for telecommunications equipment. In house building Plattenerder are rarely used.

Expiration of a foundation grounding

If you buy a house from before 2007, you should definitely check the grounding and the equipotential bonding. The cost of this check is very moderate. From the point of view of the electrician measures only the resistance at the ground. This is already sufficient to be able to make a valid statement about the equipotential bonding. It may also happen that a service technician detects a missing or insufficient potential equalization from the cable connection. This requires a grounding with sufficient cross-section to connect the amplifier from the cable connection. If this is missing, no attempt should be made to install a separate, own potential equalization. The determination of missing or insufficient equipotential bonding during the installation of the cable connection should definitely be considered as a warning signal. The next step must now be the call to the expert.

The expert opinion now follows the advice. Which potential equalization is necessary and which version is possible?>> Tips for quick readers

  • Do not want to cut costs by saving on cross sections
  • Lower costs through earthworks possible
  • All steps have to be approved by a specialist electrician
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