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Earthing Systems
Covol Engineering provides specialist design, assessment and optimisation of earthing systems for industrial, commercial and high voltage electrical installations. A correctly designed earthing system provides a safe earth connection for fault currents, helping protective devices operate correctly and reducing the risk of electric shocks, equipment damage and electrical safety issues.
Our engineers assess the full electrical installation, including the power supply, supply transformer, neutral and earth conductors, earth electrodes, exposed conductive parts, protective earth arrangements and earth fault loop impedance. We work with TT systems, IT systems and TN systems, including TN-S, TN-C, TN-C-S and protective multiple earthing arrangements, to help ensure safe and reliable continuity across your electrical systems.
Earthing for electrical power systems provide a direct electrical connection between exposed conductive parts and the earth to protect against electric shock and manage fault current. They provide a path to earth so that protective devices can operate as per their design. A single system does not meet every requirement, so understanding the correct approach for your electrical installations is critical to safety and compliance.
Our designs consider the power supply, distribution system, neutral and protective conductors, and earth electrodes to ensure reliable continuity and safe fault current management.
Both earthing and protection coordination work together to control fault energy and ensure selective device operation. Learn more about our Protection Coordination Studies to ensure your earthing systems work effectively under fault conditions.
At Covol Engineering, we design and verify all major system earthing arrangements, including:
TT System
In a TT system, the exposed conductive parts of the installation are connected to earth through independent earth electrodes. The supply neutral has a direct electrical connection to earth. Residual current devices (RCDs) are essential for fault protection in TT earthing systems.
IT System
An IT earthing system has no direct connection between the supply neutral and earth, or only a high impedance connection. This system requires continuous monitoring because the first insulation fault does not immediately create a ground fault current. IT systems are often used in high voltage installations and critical industrial facilities.
TN System
In a TN system, the supply neutral and protective functions are combined in various configurations:
TN-S system: Separate neutral and protective conductors throughout the distribution system.
TN-C system: Combined neutral and protective functions using a PEN conductor.
TN-C-S system (Protective Multiple Earthing): Combines TN-C and TN-S arrangements for reliable continuity and earth fault management.
Each system type is designed to control ground fault current, manage insulation faults and meet electricity safety standards.
Our engineers follow the fundamental principles of protective earthing and system grounding. We assess the supply transformer, supply cable and distribution network to ensure correct earth connection and reliable performance.
We reference the latest UK standards for every project, including:
BS 7430 Code of Practice for Protective Earthing of Electrical Installations
BS EN 50522 Earthing of Power Installations exceeding 1kV
BS 7671 IET Wiring Regulations
We consider issues such as touch and step potentials, high voltage earth return paths and electromagnetic compatibility to ensure the safest and most cost-effective earthing solution for your site.
Our team has extensive experience designing and verifying earthing systems for industrial electrical installations. We ensure protective earthing is correctly integrated with your electrical systems to prevent electric shock, control fault current and maintain compliance with safety standards.
Get in touch for more advice from our expert team, and learn more about Covol today.
If you are unsure whether your earthing installation is suitable, compliant or performing as expected, Covol Engineering can help. Our engineers can review your existing earthing arrangements, assess earth conductors and earth electrodes, verify earth fault loop impedance and advise on the safest and most practical way to manage fault currents across your electrical system.
We support sites with TT earthing systems, IT earthing arrangements, TN-S systems, TN-C-S systems, protective multiple earthing and complex industrial power supply arrangements. Our work helps duty holders, facilities teams and electrical engineers understand the risks, make informed decisions and maintain safe and reliable continuity.
Speak to Covol Engineering today to discuss your earthing system design, assessment or verification requirements.
Earthing systems provide a controlled connection to earth for an electrical installation. They help manage fault currents, reduce the risk of electric shocks and allow protective devices such as circuit breakers or residual current devices to operate when an earth fault occurs.
The main types of earthing systems include TT, IT and TN systems. TN systems can include TN-S, TN-C and TN-C-S arrangements. Each system handles the relationship between the neutral conductor, protective earth, earth electrode and supply network differently, so the correct design depends on the installation, power supply and safety requirements.
Protective multiple earthing, often known as PME, is commonly associated with a TN-C-S system. In this arrangement, the supply neutral is connected to earth at multiple points in the supply network, and the combined PEN conductor is separated into neutral and protective earth functions within the installation.
A TT earthing system uses an earth electrode at the installation to provide the connection to earth. The electricity supplier provides the live and neutral supply, but the consumer’s installation has its own separate earth connection. Residual current devices are normally important in TT systems because earth fault current may be limited by the resistance of the earth path.
An IT earthing system has no direct connection between the supply neutral point and earth, or it uses a high impedance connection. IT systems are often used where continuity of supply is important, because the first insulation fault may not immediately disconnect the system. They require suitable monitoring and careful engineering design.