Earthing, also known as grounding, is a safety measure used in electrical installations to prevent electric shock and damage to equipment in case of a fault. Earthing provides a low resistance path for the current to flow to the earth, thereby protecting human life and electrical equipment.
In an electrical installation, earthing is achieved by connecting the metallic parts of the electrical equipment to the earth electrode, which is typically a metal rod or a plate buried in the ground. This connection is made using a copper or galvanized iron wire, known as the earth continuity conductor.
In the event of a fault, such as a short circuit or electrical leakage, the current flows through the earth continuity conductor to the earth electrode, thereby preventing electric shock to humans and damage to equipment.
Earthing is an essential safety measure in all electrical installations, and it is important to follow the relevant guidelines and standards to ensure proper installation and maintenance.
As per CPWD guidelines, earthing is an essential safety measure in all electrical installations. The purpose of earthing is to provide a low resistance path for the current to flow to the earth in case of a fault. This prevents electric shock to humans and damage to equipment.
The following are some of the guidelines recommended by CPWD for earthing:
The earth electrode should consist of a galvanized iron pipe or a copper plate buried vertically in the ground.
The minimum depth of burial for the earth electrode should be 3 meters.
The earth electrode should be connected to the earth continuity conductor by means of a suitable clamp.
The earth continuity conductor should be of copper or galvanized iron wire, and the minimum size should be 4 sq.mm.
The earth continuity conductor should be laid in a straight line and not coiled.
The resistance of the earth electrode should be measured periodically, and it should not exceed 5 ohms.
The earth continuity conductor should be connected to all metallic parts of the electrical installation, including the metal frames of equipment and the distribution boards.
It is important to follow these guidelines to ensure proper earthing and to minimize the risk of electrical hazards.
The following are some of the earthing values required as per NBC:
Residential areas: The earthing resistance should not exceed 5 ohms.
Industrial areas: The earthing resistance should not exceed 1 ohm.
High voltage installations: The earthing resistance should not exceed 0.5 ohms.
Hospitals: The earthing resistance should not exceed 1 ohm.
Telecommunication installations: The earthing resistance should not exceed 10 ohms.
These earthing values are specified to ensure that the earthing system is effective in providing protection against electric shock and damage to equipment. It is important to follow the guidelines and standards specified by the NBC to ensure proper installation and maintenance of the earthing system. It is also recommended to periodically test the earthing system to ensure that the resistance values are within the specified limits.
Both CPWD (Central Public Works Department) and NBC (National Building Code of India) provide guidelines for earthing in electrical installations. The following are the types of earthing recommended by CPWD and NBC:
Earthing types as per CPWD:
Plate Earthing - This type of earthing is suitable for areas where soil conductivity is low. A copper or galvanized iron plate is buried in a vertical position in the ground.
Pipe Earthing - This type of earthing is suitable for areas where soil conductivity is high. A galvanized iron pipe is buried in a vertical position in the ground.
Strip Earthing - This type of earthing is suitable for rocky soil or shallow soil. A copper or galvanized iron strip is buried horizontally in a trench.
Earthing types as per NBC:
Plate Earthing - A copper or galvanized iron plate is buried vertically in the ground.
Pipe Earthing - A galvanized iron pipe is buried vertically in the ground.
Rod Earthing - A copper or galvanized iron rod is buried vertically in the ground.
Both CPWD and NBC recommend the use of high-quality materials for the earthing system, such as copper or galvanized iron wire or strip. It is important to follow the guidelines and standards specified by CPWD and NBC to ensure proper installation and maintenance of the earthing system. It is also recommended to periodically test the earthing system to ensure that the resistance values are within the specified limits.
Indian Standard for Earthing System
The Indian Standard for earthing is specified by the Bureau of Indian Standards (BIS) under the code IS 3043:2018 "Code of Practice for Earthing". This standard provides guidelines for the design, installation, and maintenance of earthing systems in electrical installations.
IS 3043 specifies the following requirements for earthing:
Earthing resistance values for different types of installations, as per the location and level of electrical activity.
Selection of earthing materials and equipment, such as earth electrodes, earthing conductors, and earthing pits.
Earthing system design, including the calculation of the number of earth electrodes required and their spacing.
Earthing system installation, including the placement of earth electrodes and earthing conductors, and the method of connecting them.
Earthing system testing and maintenance, including periodic testing of earthing resistance values, and maintenance procedures to ensure the earthing system remains effective over time.
It is important to follow the guidelines and standards specified by IS 3043 to ensure the safety and effectiveness of the earthing system in electrical installations.
Design of Earthing System
Here are some general steps to consider when designing an earthing system:
Determine the type of earthing required: Based on the electrical installation and the location, the type of earthing required can be determined. This includes selecting the appropriate type of earth electrode (plate, rod, pipe, etc.) and the material of the electrode (copper, galvanized iron, etc.).
Determine the number and spacing of earth electrodes: The number and spacing of earth electrodes are determined by the electrical load and the soil conditions. The resistance of the earth electrode system should not exceed the specified limit as per the relevant standard.
Determine the type and size of earthing conductor: The earthing conductor connects the earth electrode to the electrical equipment. The type and size of the earthing conductor depend on the electrical load, the distance between the equipment and the earth electrode, and the type of earthing electrode.
Determine the type and size of earthing pit: The earthing pit is the enclosure for the earth electrode and the earthing conductor. The type and size of the earthing pit depend on the type of earthing electrode and the soil conditions.
Determine the location of the earthing system: The location of the earthing system should be selected based on the requirements of the electrical installation, the accessibility for testing and maintenance, and the safety considerations.
Develop a detailed design plan: The detailed design plan should include the layout of the earthing system, the specification of materials, and the installation and testing procedures.
It is important to follow the guidelines and standards specified by relevant codes and standards, such as IS 3043:2018, to ensure the safety and effectiveness of the earthing system.
Installation of Earthing System
The installation of an earthing system involves the following steps:
Site preparation: The site should be cleared of any obstacles, and the area where the earth electrode and earthing pit are to be installed should be marked.
Excavation: The earth electrode and earthing pit are usually installed below the ground level. The excavation should be made to the depth and size required for the specific earthing system design.
Installation of the earth electrode: The earth electrode should be installed in the excavation and securely anchored to the ground. The earthing electrode should be surrounded by a layer of backfill material to ensure good contact with the surrounding soil.
Installation of the earthing conductor: The earthing conductor should be connected to the earth electrode and run to the electrical equipment. The conductor should be laid in a straight line with minimal bends, and should be protected from mechanical damage and corrosion.
Installation of the earthing pit: The earthing pit is the enclosure for the earth electrode and earthing conductor. It should be constructed using suitable materials, such as concrete, and should be designed to protect the electrode and conductor from damage.
Testing: Once the earthing system is installed, it should be tested to ensure that the earth resistance is within the specified limits. The testing should be performed periodically, and the results should be recorded and maintained for future reference.
Maintenance of Earthing Systems
Maintenance of earthing systems is important to ensure their continued effectiveness and safety. Here are some general steps to consider when maintaining an earthing system:
Visual inspection: Regular visual inspections should be performed to check for any signs of damage, corrosion, or other issues. Any damage should be repaired immediately.
Ground resistance measurement: The earth resistance of the earthing system should be measured periodically to ensure that it is within the specified limits. The measurement should be recorded and compared to previous measurements to detect any changes.
Soil resistivity measurement: The resistivity of the soil around the earth electrode should be measured periodically to ensure that it is within the specified limits. The measurement should be recorded and compared to previous measurements to detect any changes.
Maintenance of earthing pits: The earthing pits should be kept clean and free from debris to ensure good contact between the electrode and surrounding soil. Any damage or deterioration to the earthing pit should be repaired immediately.
Protection of earthing conductor: The earthing conductor should be protected from mechanical damage and corrosion. Any damage should be repaired immediately.
Record keeping: All maintenance activities and test results should be recorded and maintained for future reference.
Installation Process as per IS 3043:2018
The installation process for an earthing system as per IS 3043:2018 can be summarized in the following steps:
Site survey and preparation: The site should be surveyed to determine the soil resistivity, which is an important parameter in the design of the earthing system. The area where the earth electrode and earthing pit are to be installed should be marked, and any obstacles should be cleared.
Design of the earthing system: The earthing system should be designed based on the soil resistivity and the electrical characteristics of the electrical installation. The design should include the number and type of earth electrodes, the size and type of earthing conductor, and the layout of the earthing system.
Installation of the earth electrode: The earth electrode should be installed in the ground according to the design. The electrode should be securely anchored to the ground and surrounded by a layer of backfill material to ensure good contact with the surrounding soil.
Installation of the earthing conductor: The earthing conductor should be connected to the earth electrode and run to the electrical equipment. The conductor should be laid in a straight line with minimal bends, and should be protected from mechanical damage and corrosion.
Installation of the earthing pit: The earthing pit is the enclosure for the earth electrode and earthing conductor. It should be constructed using suitable materials, such as concrete, and should be designed to protect the electrode and conductor from damage.
Testing and commissioning: Once the earthing system is installed, it should be tested to ensure that the earth resistance is within the specified limits. The testing should be performed using a suitable earth tester, and the results should be recorded. The earthing system should be commissioned only after the test results are satisfactory.
Documentation: All design calculations, installation drawings, test results, and other relevant information should be documented and maintained for future reference.
It is important to follow the guidelines and standards specified by IS 3043:2018 to ensure the safety and effectiveness of the earthing system. Additionally, it is recommended to consult with a qualified electrical engineer or contractor for the installation of an earthing system.
Material required as per IS 3043:2018
The materials required for the installation of an earthing system as per IS 3043:2018 depend on the specific design and requirements of the installation. However, the following are some general materials that may be required:
Earth electrode: This is the component that is buried in the ground to provide a low impedance path to earth. Common types of earth electrodes include copper-clad steel, galvanized steel, and copper rods.
Earthing conductor: This is the cable or wire that connects the earth electrode to the electrical installation. The conductor should be made of high conductivity material such as copper or aluminum, and should be insulated to prevent any contact with other conductive objects.
Backfill material: This is the material that is used to surround the earth electrode to ensure good contact with the surrounding soil. The backfill material should be a high conductivity material such as bentonite or graphite.
Earthing pit: This is the enclosure for the earth electrode and earthing conductor. It should be constructed using suitable materials, such as concrete or brick, and should be designed to protect the electrode and conductor from damage.
Fasteners and fittings: These are the components that are used to connect the earthing conductor to the earth electrode and to the electrical equipment. The fasteners and fittings should be made of high conductivity material such as copper, and should be corrosion-resistant.
Testing equipment: This includes an earth tester or ground tester, which is used to measure the earth resistance of the earthing system. The testing equipment should be calibrated and maintained according to the manufacturer's specifications.
It is important to select the appropriate materials for the specific installation based on the design and requirements. Additionally, it is recommended to consult with a qualified electrical engineer or contractor for the selection and procurement of materials for an earthing system.
Plate Earthing as Per IS 3043:2018
Plate earthing is a type of earthing system that is commonly used in electrical installations. It involves the use of a metal plate that is buried in the ground to provide a low impedance path to earth. The following is a detailed process for plate earthing as per IS 3043:2018:
Site survey and preparation: The site should be surveyed to determine the soil resistivity, which is an important parameter in the design of the earthing system. The area where the plate is to be installed should be marked, and any obstacles should be cleared.
Plate selection: The plate should be made of a suitable material such as copper, galvanized steel, or aluminum. The size and thickness of the plate should be selected based on the electrical characteristics of the installation and the soil resistivity.
Plate installation: The plate should be installed in a vertical position, with at least 60 cm of the plate buried in the ground. The plate should be surrounded by a layer of backfill material such as bentonite or graphite, to ensure good contact with the surrounding soil.
Earthing conductor: The earthing conductor should be connected to the plate using suitable fasteners such as bolts or clamps. The conductor should be made of high conductivity material such as copper or aluminum, and should be insulated to prevent any contact with other conductive objects.
Earthing pit: The earthing pit is the enclosure for the plate and earthing conductor. It should be constructed using suitable materials, such as concrete or brick, and should be designed to protect the plate and conductor from damage.
Testing and commissioning: Once the plate earthing system is installed, it should be tested to ensure that the earth resistance is within the specified limits. The testing should be performed using a suitable earth tester, and the results should be recorded. The earthing system should be commissioned only after the test results are satisfactory.
Maintenance: The plate earthing system should be regularly inspected and maintained to ensure that it is in good working condition. The inspection should include checking for any signs of corrosion, damage, or degradation, and taking appropriate action as necessary.
Material Used in Plate Earthing as Per CPWD:
1.Earthing with G.I. earth plate 600 mm X 600 mm X 6 mm thick including accessories, and providing masonry enclosure with cover plate having locking arrangement andwatering pipe of 2.7 metre long etc. with charcoal/ coke and salt.
Pipe Earthing as Per IS 3043:2018
Pipe earthing is a type of earthing system that is commonly used in electrical installations. It involves the use of a metal pipe that is buried in the ground to provide a low impedance path to earth. The following is a detailed process for pipe earthing as per IS 3043:2018:
Site survey and preparation: The site should be surveyed to determine the soil resistivity, which is an important parameter in the design of the earthing system. The area where the pipe is to be installed should be marked, and any obstacles should be cleared.
Pipe selection: The pipe should be made of a suitable material such as copper, galvanized steel, or GI (galvanized iron). The size and thickness of the pipe should be selected based on the electrical characteristics of the installation and the soil resistivity.
Pipe installation: The pipe should be installed in a vertical position, with at least 60 cm of the pipe buried in the ground. The pipe should be surrounded by a layer of backfill material such as bentonite or graphite, to ensure good contact with the surrounding soil.
Earthing conductor: The earthing conductor should be connected to the pipe using suitable fittings such as clamps. The conductor should be made of high conductivity material such as copper or aluminum, and should be insulated to prevent any contact with other conductive objects.
Earthing pit: The earthing pit is the enclosure for the pipe and earthing conductor. It should be constructed using suitable materials, such as concrete or brick, and should be designed to protect the pipe and conductor from damage.
Testing and commissioning: Once the pipe earthing system is installed, it should be tested to ensure that the earth resistance is within the specified limits. The testing should be performed using a suitable earth tester, and the results should be recorded. The earthing system should be commissioned only after the test results are satisfactory.
Maintenance: The pipe earthing system should be regularly inspected and maintained to ensure that it is in good working condition. The inspection should include checking for any signs of corrosion, damage, or degradation, and taking appropriate action as necessary.
Material Used in Pipe Earthing as Per CPWD:
Strip Earthing as Per IS 3043:2018
Strip earthing is a type of earthing system that is commonly used in electrical installations. It involves the use of a metal strip that is buried in the ground to provide a low impedance path to earth. The following is a detailed process for strip earthing as per IS 3043:2018:
Site survey and preparation: The site should be surveyed to determine the soil resistivity, which is an important parameter in the design of the earthing system. The area where the strip is to be installed should be marked, and any obstacles should be cleared.
Strip selection: The strip should be made of a suitable material such as copper, galvanized steel, or GI (galvanized iron). The size and thickness of the strip should be selected based on the electrical characteristics of the installation and the soil resistivity.
Strip installation: The strip should be installed in a horizontal position, with at least 30 cm of the strip buried in the ground. The strip should be surrounded by a layer of backfill material such as bentonite or graphite, to ensure good contact with the surrounding soil.
Earthing conductor: The earthing conductor should be connected to the strip using suitable fittings such as clamps. The conductor should be made of high conductivity material such as copper or aluminum, and should be insulated to prevent any contact with other conductive objects.
Earthing pit: The earthing pit is the enclosure for the strip and earthing conductor. It should be constructed using suitable materials, such as concrete or brick, and should be designed to protect the strip and conductor from damage.
Testing and commissioning: Once the strip earthing system is installed, it should be tested to ensure that the earth resistance is within the specified limits. The testing should be performed using a suitable earth tester, and the results should be recorded. The earthing system should be commissioned only after the test results are satisfactory.
Maintenance: The strip earthing system should be regularly inspected and maintained to ensure that it is in good working condition. The inspection should include checking for any signs of corrosion, damage, or degradation, and taking appropriate action as necessary.
Rod Earthing as Per IS 3043:2018
Rod earthing is a type of earthing system that is commonly used in electrical installations. It involves the use of a metal rod that is driven vertically into the ground to provide a low impedance path to earth. The following is a detailed process for rod earthing as per IS 3043:2018:
Site survey and preparation: The site should be surveyed to determine the soil resistivity, which is an important parameter in the design of the earthing system. The area where the rod is to be installed should be marked, and any obstacles should be cleared.
Rod selection: The rod should be made of a suitable material such as copper, galvanized steel, or GI (galvanized iron). The size and length of the rod should be selected based on the electrical characteristics of the installation and the soil resistivity.
Rod installation: The rod should be driven vertically into the ground using a suitable driving tool such as a hammer or hydraulic press. The rod should be driven to a depth of at least 2.5 meters, or to a depth where the soil resistivity is below the specified limit.
Earthing conductor: The earthing conductor should be connected to the rod using suitable fittings such as clamps. The conductor should be made of high conductivity material such as copper or aluminum, and should be insulated to prevent any contact with other conductive objects.
Earthing pit: The earthing pit is the enclosure for the rod and earthing conductor. It should be constructed using suitable materials, such as concrete or brick, and should be designed to protect the rod and conductor from damage.
Testing and commissioning: Once the rod earthing system is installed, it should be tested to ensure that the earth resistance is within the specified limits. The testing should be performed using a suitable earth tester, and the results should be recorded. The earthing system should be commissioned only after the test results are satisfactory.
Maintenance: The rod earthing system should be regularly inspected and maintained to ensure that it is in good working condition. The inspection should include checking for any signs of corrosion, damage, or degradation, and taking appropriate action as necessary.
Maintenance Free Earthing
IS 3043:2018 does not specify any standard for "maintenance-free earthing". However, there are some alternatives to traditional earthing systems that are advertised as "maintenance-free" or "maintenance-friendly".
One such system is the Chemical Earthing System, which uses a chemical compound as an electrode to provide a low impedance path to earth. The chemical compound is placed around a copper electrode, which is then inserted into the ground. The chemical compound enhances the conductivity of the soil, which reduces the earth resistance and improves the performance of the earthing system. Chemical earthing systems are claimed to be maintenance-free and have a longer lifespan compared to traditional earthing systems.
Another alternative is the Copper Clad Steel (CCS) Earthing System, which uses a copper layer over a steel core to provide a low impedance path to earth. The steel core provides strength and durability, while the copper layer provides the conductivity. CCS earthing systems are claimed to be maintenance-free and have a longer lifespan compared to traditional earthing systems.
It is important to note that the effectiveness of any earthing system, including "maintenance-free" systems, depends on the soil resistivity, installation practices, and other factors. It is recommended to consult with a qualified electrical engineer or contractor to determine the most suitable earthing system for a specific application. Additionally, regular inspections and maintenance should be performed to ensure that the earthing system is in good working condition.
Chemical Earthing System
The Chemical Earthing System is not specifically mentioned under any particular code in India. However, it is generally accepted as a viable alternative to traditional earthing systems and is commonly used in many electrical installations.
The Chemical Earthing System typically consists of a copper electrode surrounded by a chemical compound that enhances the conductivity of the soil and provides a low impedance path to earth. The chemical compound may include a mixture of bentonite clay, salt, and other additives.
While there is no specific code for Chemical Earthing Systems, it is important to ensure that the system is installed in accordance with applicable standards and guidelines for earthing systems, such as IS 3043:2018 "Code of Practice for Earthing" and IEEE 80 "Guide for Safety in AC Substation Grounding". Additionally, regular inspections and maintenance should be performed to ensure that the earthing system is in good working condition.
Installation of Chemical Earthing System
The installation process for a Chemical Earthing System generally involves the following steps:
Site Preparation: Identify a suitable location for the earthing system, away from any underground utilities or obstructions. Dig a pit in the soil to accommodate the earthing electrode.
Electrode Placement: Insert the copper electrode into the pit and ensure that it is vertical and centered in the pit. The electrode should be long enough to reach a depth where the soil resistivity is low.
Backfilling: Fill the pit with the chemical compound, which is typically a mixture of bentonite clay, salt, and other additives. The chemical compound should be compacted around the electrode to ensure good contact with the soil.
Connection: Connect the copper electrode to the equipment to be grounded, using suitable copper wires and clamps.
Testing: Perform an earth resistance test to ensure that the earthing system is functioning properly. The test should be conducted in accordance with applicable standards, such as IS 3043:2018 and IEEE 80.
It is important to follow the manufacturer's instructions and applicable standards when installing a Chemical Earthing System. Additionally, regular inspections and maintenance should be performed to ensure that the earthing system is in good working condition.
Copper Clad Steel (CCS) Earthing System
Installation of Copper Clad Steel (CCS) Earthing System
The installation process for a CCS Earthing System is similar to other earthing systems and typically involves the following steps:
Site Preparation: Identify a suitable location for the earthing system, away from any underground utilities or obstructions. Dig a pit in the soil to accommodate the earthing electrode.
Electrode Placement: Insert the CCS electrode into the pit and ensure that it is vertical and centered in the pit. The electrode should be long enough to reach a depth where the soil resistivity is low.
Backfilling: Fill the pit with a suitable backfill material, such as bentonite clay or a mixture of bentonite and sand. The backfill material should be compacted around the electrode to ensure good contact with the soil.
Connection: Connect the CCS electrode to the equipment to be grounded, using suitable copper wires and clamps.
Testing: Perform an earth resistance test to ensure that the earthing system is functioning properly. The test should be conducted in accordance with applicable standards, such as IS 3043:2018 and IEEE 80.
CCS Earthing System offers several advantages over other earthing systems. The copper coating provides excellent corrosion resistance, while the steel core provides good strength and durability. Additionally, CCS earthing systems can be a cost-effective alternative to solid copper earthing systems, while still providing good performance and reliability.
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