Earth electrodes are electrical conductors, metallic rails, pipes, grids, profiles or other electrically conductive bodies that are connected to the earth and have a low resistance, the earth resistance, to it.
In general, earth electrodes are divided into natural earth electrodes, surface earth electrodes and deep earth electrodes. Natural earth electrodes include building and foundation components that are connected to the earth over a large area via metallic bodies. The other earth electrodes differ in how deep and where they are installed. There are surface earth electrodes, which include ring earth electrodes, mesh earth electrodes and radiation earth electrodes, and deep earth electrodes and foundation earth electrodes.
Earthrods are installed vertically in the ground at a depth of several meters. These earth electrodes can be metal rods, pipes or cross sections that are driven vertically into the ground. The advantage of deep installation is the constant resistance to the ground. The grounding resistance of the Tifenerder should be less than 10 ohms, the minimum length depends on the lightning protection class and may be between 2.5 m and 10 m. They are connected to the equipotential bonding rail.
Foundation earth electro des are those that are installed as a closed ring in the concrete foundations of the outer wall of the building, in the moisture area, i.e. below the moisture barrier. According to DIN regulations, foundation grounding electrodes must be made of 30 mm x 3.5 mm or 25 mm x 4 mm galvanized strip steel or 10 mm diameter round steel. Foundation earth electrodes are specified in DIN 18014.
Radial earth electrodes belong to the group of deep earth electrodes. In this type of earth electrode, several steel rods, pipes or strip earth electrodes are driven into the earth at an angle of 45° from a central point. Radial earth electrodes are connected to the equipotential bonding system.
In contrast to deep earth electrodes, surface earth electrodes are laid horizontally in the ground, at a depth of less than one meter. Surface earth electrodes can be metallic lattice or mesh constructions, metal or copper plates, or radially arranged rods.
Ring earth electrodes are flat earth electrodes that are installed in a ring around the building. Ring earth electrodes are band earth electrodes, they are preferably made of V4A steel or a leaded copper strip and are located about 0.5 m below the ground surface and at a distance of about 1 m from the building. They are used for external lightning protection.
The building earth electrode (BWE) is a structural earth electrode. It consists of the connections of the foundation earth electrodes to each other or to the reinforcements of the concrete and the steel girders of the structure.