Equipment earthing is a connection between the body of electrical equipment like motor, generator, or other to the Earth.
Point to be Noted:
- Equipment earthing is based on IS:3043-1987 Standards.
- Classification of electrical equipment IS: 9409-1980
- Important rules for safety and earthing practice is based on IE rules 1956
- Guide on effects of current passing through human body – IS:8437-1997
- Protection of buildings and structures from lightning – IS:2309-1969
Terminology in Equipment Earthing:
- Earth: Point at which electric potential at any point is taken as zero.
- Earth Electrode: It is a conductor which is used as electrical connection to earth.
- Earth Electrode Resistance: It is resistance of an earth electrode.
- Earthing Conductor: It is also known as Earthing Lead which provide connection between earthing to equipment.
- Touch Potential: It is potential difference between grounded metallic structure (tower, equipment, substation support etc) to point on the earth’s surface separated by a horizontal reach of one Metre.
- Step Potential: It is potential difference between two points on the earth’s surface separated by a distance one step.
- Earth Grid: A System of grounding electrodes consisting of interconnected connectors buried in the earth to provide a common ground from electrical devices and metallic structures.
- Earth Mat: It formed by a grid of horizontally buried conductors to dissipate the earth fault current to earth and also as an equipotential bonding conductor system.
