Earthing: Basis for safety and functionality
Setting the right basis with foundation and ring earth electrodes
Whether existing or new buildings, a functioning earth-termination system is the prerequisite for protecting people from dangerous high voltages and for the safe operation of electric systems in buildings.
An earth-termination system forms the basis for the proper function of the:
New building: Basic elements of an earth-termination system
- A - Foundation earth electrode
- B - Ring earth electrode
- C - Main earthing busbar and fixed earthing terminal
- D - Connections to the external lightning protection system
Tip
Stay flexible by providing fixed earthing terminals for the external lightning protection system at the initial phase of construction. This allows you to retrofit an external lightning protection system more easily at lower cost.
Normative requirement for foundation and ring earth electrodes
A safe and cost-effective earth-termination system can be implemented with the help of foundation or ring earth electrodes – over the entire lifetime of the building.
If a lightning protection system is installed, the extended requirements of EN 62305-3 have to be observed.
Foundation earth electrode
Foundation earth electrodes are installed as a closed ring in the foundations of the exterior walls of the building.
In case of large buildings, additional cross connections with a mesh size of max. 20m x 20 m have to be observed.
Planning
Careful design and implementation of the foundation earth electrode are of central importance since omissions and errors cannot be corrected after the concrete has set. Therefore, agreement between architects, construction companies, electrical engineers and lightning protection/electrical installation companies is required at the design stage.
Implementation
Foundation earth electrodes are installed in the concrete foundation and covered by at least 5 cm of concrete to ensure corrosion protection. However, this conductive earth connection may no longer be ensured (foundations with increased earth contact resistance) due to various building construction measures (e.g. when constructing a building made of waterproof concrete). In this case, a corrosion-resistant ring earth electrode must be installed.
In Germany, DIN 18014 must be used for planning, implementing and documenting foundation earth electrodes.
Ring earth electrode
Ring earth electrodes are used for increased earth contact resistances (e.g. building made of waterproof concrete or perimeter insulation).
Design
Special features have to be considered at the design stage of foundation earth electrodes, for example
- Connection to individual foundations
- Installation of the ring earth electrode below insulating base layers.
Implementation
Ring earth electrodes are installed in the ground as a closed ring around the structure. In case of large buildings, additional cross connections with a mesh size of max. 20 m x 20 m have to be observed. If a lightning protection system is planned, the mesh size has to be reduced to 10 m x 10 m.
In Germany, DIN 18014 must be used for planning, implementing and documenting foundation earth electrodes.
Downloads
Foundation earth electrode
FAQ earthing
- Ring earth electrode or foundation earth electrode?
- Which mesh size is required?
- Which distances have to be kept from the edge of the building?
- What has to be observed for buildings with pad foundations?
... Here are the answers to frequently asked questions concerning earthing.
Existing building
Retrofitting and restoration of earth-termination systems
A functioning earth-termination system ensures that buildings are safe and is a prerequisite for protecting people - even in existing buildings. Earth rods or ring earth electrodes can be used for retrofitting.
