What are the most common grounding systems used in Electrical Design?

Often forgotten and unusually misunderstood is the Protective Neutral Bonding used in the TNC-S (PNB) system. These are always on private networks, look on paper like a TNC-S system but without a DNO interface. These involve a supply from a private transformer with a Neutral conductor providing a combined function, a N-E link in the LV switchboard to create a low impedance earth return path. These usually have local earth farm(s) to assist with step and touch potential and can combine with the HV earthing systems in ‘cold’ sites. In relation to the afore mentioned TNC-S system and their high earth resistance risk, PNB systems rarely suffer from this and can be assessed in the same way as a TN-S earthing system and for bonding calculations.

In data center design, we always adopt TN-S or TT system for electrical installation / distribution. TN-C is not preferable as it will create "noise" to the server and the harmonic content in the neutral cable is considered high. In additions, we also adopt TIA-607 for telecommunication grounding/bonding.

We prefer to connect the neutral to PE in the main LV S.W.G and locate the earth leakage protection CT at this link. this way the system is considered TNC from transformer to main LV S.W.G and after that change the system to TNC-S to distribute both Neutral and PE separately through the system

A TN (Terre-Neutre) grounding system is a common electrical grounding configuration used in industrial settings. It involves connecting the electrical system's neutral point directly to the ground, providing a reliable and safe path for fault currents. This configuration is often chosen for its simplicity and cost-effectiveness in many industrial applications.

The TN system and its variety of combinations are the most common systems in use in buildings and in relatively limited distance between the source and the load. It worth noticing that the TNCS system requires a very good electrode to earth which can be achieved by either applying foundation earthing or multi-electrodes network. This system suffers from constant leakage current to the building reinforcement system and can increase reinforcement corrosion rates. This system also doesn't allow the disconnection of the neutral before the branch of the earth wire. Despite its disadvantages this system is considered safe, reliable and relatively cheap to achieve. The TNC system is only allowed is only allowed in limited countries.

TN system is the most commonly used in industry, I also worked many times with TN grounding systems. This system is easy and safe also

I have always wondered why we haven’t moved to using an impedance earth on domestic properties? What are others thoughts on that?

In TN-C-S grounding systems, a lesser-known issue is the electromagnetic interference (EMI) caused by harmonic currents in the combined neutral and protective conductor. This can adversely affect sensitive electronic equipment in industrial environments. To combat this, engineers often employ additional electromagnetic compatibility measures, such as shielded cabling and specialized filters. These steps are crucial for maintaining the precision and safety of electronic devices in settings where such interference can significantly impact operational efficiency.

This approach enhances safety and reduces the risk of electric shock, especially in environments where a reliable ground connection is critical. It is often used in industries with stringent safety requirements, such as manufacturing, petrochemical, and power generation.

TT system is also required in buildings with multiple power sources such as generators and solar / renewable energy sources.

In Kenya TT and PME are the most widely used earthing systems for domestic power sub-distribution. Kenya follows British Standards and therefore we use the term earthing rather than grounding. PME is useful where the earth/ ground lacks moisture most of the year to guarantee safety of the electrical system to the consumers.

Bonjour, ça dépend évidemment du type d'installation mais au vu du nombre d'habitation, le système TT est je pense le plus connu et répandu

The IT system is used in Hospital power distribution facilities, where the sustainability of system is important and we do not want to experience any disconnection at the event of first fault. Thus to find out about the first fault happened in the system we should you special fault detectors which are called LIM devices (Line Insulation Monitoring), these equipment find the fault and alarm for the first fault.

Although considered relatively rare within the UK, and only ever typically seen in installations such as Operating Theatres, where continued service is life-critical. IT is now seeing more use within another field, namely Battery Energy Storage Systems (BESS), whom are arriving in the UK pre-configured in this manner from their manufacture in the far east.

In IT and communications, a common concept is electronic earthing. Usage is prevalent in communication systems. This earth is ultimately connected to the main earth grid somewhere. A separate dedicated earth helps filter out noise in the power line earthing which may affect the sensitive electronics.

An IT (Isolated or Insulated Termination) reduce the risk of electrical shock and maintain critical operations in case of a ground fault. It's commonly used in data centers and critical infrastructure where uninterrupted power supply is essential.

Ships and marine installations almost always use ungrounded power systems with earth fault monitoring. One reason is to avoid hull corrosion problems.

With a TN-C-S system you can have issues when the neutral becomes disconnected. The neutral can develop a voltage that is significantly higher than the ground. If this happens then there is a real issue with the main earth bar at the consumer as this is connected to neutral. So to get round that TT systems are used where your taking power out with the equipotential zone of the consumer. car charger, hot tub etc. they put in an earth rod and make their own earth that's separate from the consumer earth terminal. If they didn't, then this raised potential could be present on the metal work of the appliance. and the user could receive an electric shock if they were to be grounded and touch that metal appliance.

Due to the complex nature of Earthing / Grounding Systems, and their critical and fundamental function within other power parts of the power system, such as Protection, it is always best to consult the relevant engineering standards when carrying out design works. Within the UK, standards such as BS 7671, BS EN 7430 and BS EN 50522 shall be the absolute minimum. Furthermore, and if ever in doubt, do not hesitate to consult with an Earthing Specialist, of which, there are a number of extremely competent and experienced individuals currently practicing within the UK marketplace.

In industry where the customer has their own transformers, the TN-S system is the most common. AS3000 and AS3010 are written mostly around the TN-S-C system with multiple earthed neutral which can add some confusion about essential requirements.

A seleção do sistema de aterramento em um projeto elétrico é influenciada por diversos fatores, incluindo a fonte e carga de energia, regulamentações locais e disponibilidade de recursos. É crucial avaliar cuidadosamente as vantagens e desvantagens de cada sistema para assegurar a qualidade e confiabilidade da instalação. Consultar especialistas é fundamental para garantir conformidade com normas de segurança e eficiência.

In an electrical system, effective grounding ensures a safe working environment as well as proper equipment performance. A “ground” is a conducting connection by which an electrical circuit or equipment is connected to earth. This connection is used to establish and maintain as closely as possible the potential of the earth on the circuit or equipment connected to it. This connection to the earth provides a low impedance path for electrical currents to travel under fault conditions.

It is important note that grounding is only for three phase systems. It is not applicable for single phase appliances or circuits. For example, the connection between circuits (sockets) in the residential building is ring connection between the line (phase A/B/C) and Neutral (N). The neutral is a return path for leakage current to the system three phase system ( Star Connection ). Another important note is the earthing and grounding are different systems but it share the same purpose. For instance, earthing is used to discharge the electrostatic charge or charge cause by lightning. On the other hand, ground is providing path for leakage current during fault. Both of them should provide high impedance and high protection.