A Guide to Earthing Systems

Earthing is the fundamental basis for the safe function of every electrical system and its protection devices. It ensures reliable operation and protects people from dangerous electric shock and fire hazards. OBO Bettermann’s Guide to Earthing Systems is a comprehensive technical document that provides the essential principles, standards, and practical applications for designing and installing effective earthing systems. This article summarizes the key content from this valuable resource.

Why This Guide Matters

The earthing system performs several critical functions in any electrical installation, making it a cornerstone of electrical safety and system reliability.

Personal Safety: It provides a safe path for fault currents and lightning currents to dissipate into the earth, protecting people from dangerous electric shocks.
Equipment Protection: It protects equipment from unintentional contact with live parts and helps to limit damage from electrical faults.
System Functionality: It ensures the correct operation of protection devices by providing a low-impedance path for fault current, which is essential for devices like circuit breakers to trip quickly.
Electromagnetic Compatibility (EMC): It reduces electrical noise and ensures good power quality, which is especially critical for buildings with IT systems and sensitive data cabling.

The guide emphasizes that a well-designed earthing system is not just a regulatory requirement, but a key part of a building’s functional and safety infrastructure.

Understanding Normative Requirements

The guide references the key international and national standards that govern the planning and installation of earthing systems:

IEC 60364-4-41: Protection against electric shock
IEC 60364-5-54: Earthing arrangements and protective conductors
IEC 62305-3 / VDE 0185-305-3: Protection against lightning – Physical damage to structures and life hazard
DIN 18014: Foundation earth electrodes – General planning principles for new buildings in Germany
EN 50310: Application of equipotential bonding and earthing in buildings with information technology equipment

A key requirement across these standards is that the earthing resistance of the system should be as small as possible. The guide notes that a value below 10 Ω is generally recommended for lightning protection systems to ensure safe and effective dissipation of lightning currents.

Earthing System Types and Materials

The guide provides a detailed overview of the two primary types of earthing systems as defined by international standards.

Type A Earthing Systems

These are vertical earth electrodes, typically used where soil conditions are suitable and space is limited.

Examples: Earth rods (deep-driven or plate earth electrodes) and horizontal earth electrodes.
Application: Commonly used to supplement other earthing arrangements or as the primary system for individual structures.

Type B Earthing Systems

These are surface earth electrodes, which are laid around the building’s foundation.

Examples: Ring earth electrodes and foundation earth electrodes.
Application: Foundation earth electrodes are a mandatory requirement for new buildings in Germany (per DIN 18014) and are considered best practice elsewhere.

Conductor Materials

The guide details the available materials for earthing conductors, noting that material selection is critical for longevity and performance, especially in corrosive soils.

Galvanised Steel: Widely used for standard applications. The guide specifies different zinc coatings for use in the ground (e.g., 500 g/m²) versus above ground (e.g., 225 g/m²) to prevent corrosion.
Stainless Steel: Required for use in potentially corrosive soil conditions, especially when in contact with a building’s concrete foundation reinforcement.
Copper: Offers high conductivity and corrosion resistance and is available as round or flat conductors, often used for ring earth electrodes.

Practical Implementation

Beyond the theory, the guide provides practical, step-by-step guidance for designing and installing a compliant earthing system.

Foundation Earth Electrodes

A dedicated chapter details the installation of a foundation earth electrode (Type B), as per DIN 18014. It covers execution details for different foundation types, including unreinforced foundations and pad foundations. Construction companies are advised to allow supervision of the installation and acceptance of the earthing system by electrical and lightning protection specialists to ensure compliance.

Ring Earth Electrodes

The guide specifies that a ring earth electrode should be installed as a closed loop at a distance of at least 1.0 meter from the building and at a depth of 0.5 meters, with at least 80% of its total length in contact with the ground.

Earth Rods (Type A)

Guidance is provided on the installation of earth rods, including deep earthing systems. The range includes systems like OMEX and LightEarth, with details on their specific connection methods and corrosion protection.

Specific Applications

The guide also addresses the unique earthing requirements for specialized environments.

Photovoltaic (PV) Systems: The guide, and OBO’s related materials, highlight the need for earthing systems for PV arrays, including requirements for functional earthing of metallic substructures and the conductor cross-sections needed depending on whether a lightning protection system is present.
Wind Power Plants: Earthing for wind turbines is a complex topic, with the guide noting that the foundation must not only support the structure but also safely dissipate lightning currents. OBO offers specific solutions for these installations, such as ring earth conductors placed around the tower base.

Digital Planning Support

To assist with the complexity of earthing system design, OBO Bettermann offers a digital planning tool called OBO Construct. This tool supports the user in selecting a suitable earthing system by guiding them through the design steps and automatically calculating required quantities. The output can be exported as a parts list for ordering or to share with clients, bridging the gap between design and procurement.

Conclusion: A Vital Resource for Electrical Professionals

OBO Bettermann’s Guide to Earthing Systems is an invaluable reference for electrical engineers, installers, and consultants. By compiling essential standards, product specifications, and practical design advice into a single document, it provides a solid foundation for designing safe, reliable, and compliant earthing solutions. The guide’s systematic approach to topics like system types, material selection, and specific applications helps professionals navigate the critical task of protecting people and equipment through an effective earthing system.

Download the Full Guide

This overview is based on OBO Bettermann’s comprehensive guide. The full document provides a much deeper dive into each topic, with detailed diagrams and specific product recommendations.

The guide is available to download for free:

Download the Guide to Earthing Systems (PDF)