Grounding and Earthing: A Comprehensive Guide for Electrical Installations
1. Purpose
Grounding and earthing are essential safety measures in electrical installations. They serve to:
- Limit voltage levels to ground
- Ensure the proper functioning of protective devices
- Reduce the risk of electrical shock
2. Placing or Grounding: Definition
Grounding involves connecting an electrical circuit or conductive part to the earth using an electrode or group of electrodes buried in the ground. This creates a low-resistance path for electrical currents to flow, preventing dangerous voltage differences and reducing the risk of electrical hazards.
3. Connections to Ground
Grounding can be achieved through various methods, including:
- Protectionism driver: Connects protective devices to ground
- Main equipotential joined conductor: Connects all conductive parts to ground
- Driver or linia terra amb electrode denllaç post a terra: Connects the main equipotential bonding conductor to the ground electrode
- Driver equipotencialitat supplementary main terminal terra: Connects additional equipotential bonding conductors to the main earth terminal
- Massa, element driver canalizacio main daigua metal, terra-making: Connects metal water pipes and other conductive elements to ground
3.1. Grounding Electrodes
Grounding electrodes can take various forms, including:
- Rods
- Tubes
- Plates
- Bare conductors
- Metal mesh
- Buried concrete reinforcement
3.3. Grounding Terminals
The main earth terminal should be accessible and equipped with a device to measure grounding resistance. It should also be removable for maintenance purposes.
3.4. Protective Conductor
The protective conductor connects exposed conductive parts to ground to prevent indirect contact with live parts.
4. Reasons for Grounding Protection
Grounding is essential for protection against electric shock in TN, TT, and IT systems. It ensures that fault currents are safely discharged to ground, preventing dangerous voltage levels on exposed surfaces.
4.1. Grounding and Protective Conductors for Voltage Control Devices to Default
Grounding should be isolated to prevent contact with the protective conductor. The protective conductor should be connected to all exposed conductive parts that may become energized during a fault condition.
5. Earthing for Functional Reasons
Earthing for functional reasons ensures the proper operation of equipment and the reliability of the installation.
6. Reasons for Grounding Combination of Protection and Functional
When grounding is necessary for both protection and functional reasons, protection measures take precedence.
7. Drivers CPN (Also Called PEN)
In TN systems, the protective conductor and neutral conductor can be combined into a single CPN conductor with a minimum cross-sectional area of 10 mm² in copper or aluminum.
8. Drivers Equipotentiality
The main equipotentiality driver should have a cross-sectional area of at least half that of the largest protective conductor in the installation, with a minimum of 6 mm².
9. Strength of Earthing
The earth electrode should be dimensioned to ensure that the earth resistance does not exceed the specified value under all foreseeable circumstances. The earth resistance should be low enough to prevent dangerous contact voltages.
10. Separate Earthing
Separate earthing is considered when the voltage between two grounding points exceeds 50 V during an earth fault.
11. Separation of the Earthing the Masses of Facilities Use and the Masses of Processing Center
Grounding of facility masses and processing center masses should be separate to prevent dangerous contact voltages during earth fault evacuation in the processing center.
12. Review of Earthing
The main contractor or authorized installer must verify the earthing installation.