The basic prerequisite for a safe electrical system is its earthing. For this reason energy suppliers, in their technical stipulations concerning connnections, and the standard DIN 18015-1 both specify that foundation earthing must be installed in new buildings.
In addition, foundation earthing can perform universal functions for other household systems, e.g. for communication systems, for antennae and for lightning conductors.
The construction of foundation earthing is regulated in the standard DIN 18014. It is fitted as a closed ring in the exterior part of the foundations of the building. If using a foundation plate system, the earthing should be laid as a complete circuit in the outer walls of the foundation. In all cases the foundation earthing circuit must be so installed that it is completely surrounded by concrete. This prevents erosion and ensures a virtually unlimited operating life.
Connection terminals make it possible to establish links to the foundation earthing. These terminals consist of connector strips and connector plates. The connector strips lead through from the foundation earthing to the mains connection point in the house. The length of the connector strips, measured from their entry into the room, should be at least 1.5 metres. For concrete walls it is best to use a connector plate fused into the wall to link the earthing to the electrical system.
The foundation earthing is a component of the electrical system and the building owner or architect is responsible for organising its construction. It must be taken into account right from the start of the project when estimates for work on the structure of the building are being considered. The installation of the foundation earthing must be overseen by a construction engineer, a consultant electrical engineer or a specialist in lightning protection.
Modern construction techniques
In energy-efficient houses (with under-structure perimeter insulation) or in buildings with a seal against ground water (use of water-impermeable concrete) standard foundation earthing does not usually function. Its effectiveness can be determined by taking measurements through the electrical system. If the earthing is found to be defective the land around the exterior of the building must be dug up and a ring earthing system made of stainless steel should be installed. This then assumes the role of the foundation earthing.
To avoid such additional and unplanned costs the ELEKTRO+ Initiative offers a comprehensive brochure outlining the range of installation techniques for foundation earthing systems. This publication can be ordered or downloaded free of charge by clicking on the link.