Electrical earthing systems are fundamental in ensuring safety and functionality in electrical installations. In South Africa, these systems adhere to the specifications outlined in the South African National Standards (SANS). Let’s delve into the different types of electrical earthing systems specified by SANS, accompanied by illustrations depicting each system.
1. TT System (SANS 10142-1:2020)
The TT system involves the connection of electrical equipment to earth through individual earthing electrodes. It’s commonly used in locations where a reliable earth connection via the supply system is not feasible. In this system, both the neutral and protective earth conductors are separated. Illustrations show dedicated electrodes connecting the electrical installation to the earth.
2. TN-S System (SANS 10142-1:2020)
The TN-S system maintains separate conductors for the neutral and protective earth. It involves an independent earth conductor running parallel to the supply conductor, ensuring a reliable earth connection. Diagrams illustrate the distinct paths of the neutral and protective earth conductors, meeting SANS specifications for safe electrical installations.
3. TN-C System (SANS 10142-1:2020)
In the TN-C system, a combined neutral and earth conductor, known as a PEN conductor, is used for distribution. This system requires careful implementation to avoid the risk of loss of earth continuity. Illustrations demonstrate the PEN conductor’s configuration and its connection points to ensure compliance with SANS regulations.
4. TN-C-S System (SANS 10142-1:2020)
The TN-C-S system combines elements of both TN-C and TN-S systems. It uses a combined neutral and earth conductor (PEN) for distribution, which then separates into separate neutral and earth conductors closer to the electrical installation. Detailed illustrations depict the transition from the combined PEN conductor to individual neutral and protective earth conductors.
Conclusion
Electrical earthing systems in South Africa, guided by SANS standards, play a critical role in ensuring the safety and reliability of electrical installations. Understanding and implementing the appropriate system as per SANS codes is imperative for electrical engineers and installers to safeguard both people and property from electrical hazards.