Earthing or grounding is an essential aspect of electrical installations and is necessary to ensure the safety of personnel and equipment. Earthing primarily consists of connecting a metal conductor or earth electrode to the Earth's surface. There are different types of earthing systems that are used depending on the application, environment, and safety requirements. In this article, we will discuss the various types of earthing systems and their advantages and disadvantages.
TT (Separate):
The TT earthing system is where each electrical device is connected to its own local earth electrode. The earthing electrode is connected to the earth pit directly, and not connected to any other conductive material. This type of earthing system is commonly used in residential areas.
TN-S (Combined):
The TNS earthing system is a combination of the TN and TT earthing systems. The electrical devices are connected to a common earth point, which is then connected to both the earth electrode and the
earth pit. This type of earthing system is commonly used in medium-sized industrial and commercial buildings.
TN-C-S (Combined):
The TN-C-S earthing system is a combination of the TN and IT earthing systems. The electrical devices are connected to a common earth point, which is then connected to the earth electrode and the earth pit through a monitoring resistor. This type of earthing system is commonly used in larger industrial and commercial buildings.
IT (Isolated):
The IT earthing system is where the electrical devices are isolated from the earth, and the only connection to the earth is through a monitoring resistor. The monitoring resistor is used to detect any earth fault currents and is typically set at a low value to ensure rapid detection. This type of earthing system is commonly used in sensitive electronic equipment.
TN-C (Combined):
The TN-C earthing system is where the combined neutral and protective conductor (PEN) serves as the earth connection for electrical devices. The PEN conductor is connected to the earth electrode, which is then connected to the earth pit. This type of earthing system is commonly used in small commercial and residential buildings.