TNCSjärjestelmässä

TNCSjärjestelmässä refers to the TNCS earthing system, a configuration used in electrical power distribution. In this system, the neutral point of the transformer is directly earthed, and the metal casing of electrical equipment is connected to this earthed neutral. The 'C' in TNCS stands for Combined, indicating that the neutral and protective earth conductors are combined in some parts of the system, typically the main supply cable from the transformer.

The primary advantage of the TNCS system is its cost-effectiveness, as it requires only one conductor for both neutral and protective earthing up to the point of separation. This reduces installation complexity and material costs. It provides effective protection against electric shock, as faults to the metal casing will result in a low-impedance path to earth, causing a large fault current that should trip protective devices like circuit breakers or fuses.

However, the TNCS system also has potential drawbacks. The combination of neutral and earth conductors can lead to circulating currents in the protective earth conductor under normal operating conditions. This can cause interference with sensitive electronic equipment and may pose a risk of electric shock if the combined conductor is damaged or becomes disconnected. For these reasons, the separation of neutral and earth conductors is typically done at the consumer's intake point, creating a TN-S system within the installation. Careful design and adherence to regulations are crucial when implementing and maintaining TNCS systems to ensure safety and reliability.