Equipment earthing, also known as equipment grounding or protective grounding, is a safety measure that involves connecting the metallic parts of electrical equipment and appliances to the earth or ground. The purpose of equipment earthing is to provide a low-resistance path for fault currents to flow, ensuring the safety of individuals and protecting the equipment from electrical faults.
Following are the points regarding equipment earthing:
- Protection against Electric Shock: By connecting the metallic parts of electrical equipment to the ground, equipment earthing helps prevent the buildup of dangerous voltages on the equipment’s surfaces. In the event of a fault or insulation failure, any fault current will flow through the equipment grounding conductor, quickly tripping the protective device and minimizing the risk of electric shock to users.
- Fault Current Path: Equipment earthing provides a dedicated path for fault currents to flow. If a fault occurs, such as a short circuit or ground fault, the fault current will preferentially flow through the grounding conductor rather than through unintended paths, such as through a person or other conductive objects. This helps protect both individuals and the equipment itself.
- Voltage Stabilization: Equipment earthing helps stabilize the voltage on the equipment’s conductive parts. By connecting them to the ground, any static charges or induced voltages are dissipated, ensuring that the equipment operates at the intended voltage levels and reducing the risk of damage due to overvoltage.
- Bonding of Metallic Parts: In addition to equipment grounding, it is important to establish proper bonding between metallic parts of electrical equipment and structures. Bonding ensures that all metallic parts within a facility are at the same electrical potential, minimizing the risk of potential differences that could lead to electrical hazards or equipment damage.
The equipment earthing system includes following components:
- Grounding Conductor: A dedicated conductor, often made of copper or aluminum, that connects the metallic parts of the equipment to the grounding electrode or grounding busbar.
- Grounding Electrode: A metal rod or plate buried in the ground, providing a low-resistance connection to the earth. Common grounding electrodes include copper rods, conductive plates, or grounding grids.
- Bonding Conductors: Additional conductors that connect metallic structures, enclosures, and equipment to ensure proper bonding and equalization of electrical potential.