What is TNS Earthing System?

In India, TNS (TN-S) earthing systems are commonly used in residential and commercial buildings and are required by electrical codes and standards. These systems are a safe and reliable choice for electrical installations in India, and are compatible with a wide range of electrical devices and appliances.

In addition to being widely used in India, TNS earthing systems are also commonly used in many other countries around the world. They are a popular choice for electrical installations due to their safety, reliability, compatibility, and cost-effectiveness.

Purpose of a TNS Earthing System

The main goal of a TNS (TN-S) earthing system is to ensure the safety of an electrical installation and protect people and property from electrical hazards. This is achieved by providing a low-resistance connection to the ground, which helps to dissipate electrical current and prevent electrical shocks or fires.

In a TNS earthing system, the electrical supply is connected to the “neutral” conductor (N), and the earth conductor (S) is connected to a metallic structure, such as a metal water pipe or metal rod, that is buried in the ground. The electrical installation is connected to the “live” conductor (T). If there is a fault in the electrical installation (such as a short circuit), the fault current will flow through the earth conductor to the ground, rather than through the electrical installation or the people using it. This helps to prevent electrical shocks and damage to the electrical installation.

It is important to note that a TNS earthing system will not prevent a fault or short circuit from occurring, but it will help to ensure that the fault current is safely dissipated to the ground, protecting people and property from electrical hazards.

TNS Earthing System VS TN-C, TN-C-S, IT

There are several different types of earthing systems that are used in electrical installations, including TN-S, TN-C, TN-C-S, and IT. Each of these systems has its own specific characteristics and is used in different situations depending on the needs of the electrical installation and the requirements of local electrical codes and standards.

A TN-C earthing system is similar to a TN-S system, but in this case the earth conductor (C) is also used as the neutral conductor. This means that the earth conductor is connected to both the neutral point of the electrical supply and to a metallic structure that is buried in the ground. TN-C systems are typically used in smaller installations, such as in single-phase residential dwellings.

A TN-C-S earthing system is a combination of the TN-C and TN-S systems. In this case, the earth conductor (C) is used as the neutral conductor, and there is also a separate earth conductor (S) that is connected to a metallic structure buried in the ground. TN-C-S systems are often used in larger installations, such as in multi-phase commercial or industrial buildings.

An IT (isolated neutral) earthing system is a type of earthing system that is used in systems with a high voltage level (greater than 1 kV). In an IT system, the neutral conductor is not connected to the earth or any other metallic structure. Instead, the neutral conductor is isolated from the earth, and the electrical installation is connected to both the live conductor (T) and the neutral conductor (N). IT systems are typically used in power generation and transmission systems, as well as in some industrial applications.

TNS earthing systems are generally less expensive to install and maintain than other types of earthing systems, such as IT systems. There are several reasons why TNS earthing systems may be less expensive to install and maintain.

1. Simplicity: TNS earthing systems are relatively simple and straightforward, with fewer components and a more straightforward installation process. This can make them less expensive to install and maintain than more complex systems.
2. Compatibility: TNS earthing systems are compatible with a wide range of electrical devices and appliances, including those with a neutral conductor. This means that they can be used in a variety of applications without the need for specialized equipment or materials.
3. Materials: TNS earthing systems typically use inexpensive materials, such as copper or aluminium conductors and metallic structures (such as metal rods or water pipes) for the earth connection. This can make them less expensive to install and maintain than systems that use more expensive materials.
4. Labour: TNS earthing systems are relatively easy to install and maintain, which can result in lower labour costs compared to other types of earthing systems.

It is important to note that the cost of installing and maintaining an earthing system will depend on a variety of factors, including the size and complexity of the electrical installation, the materials used, and the labor required. TNS earthing systems may be less expensive to install and maintain than other types of earthing systems in some cases, but this will depend on the specific circumstances of each installation.

Designing a TNS Earthing System

There are several special considerations that should be taken into account when designing a TNS (TN-S) earthing system for a particular location or type of building:

1. Local codes and standards: It is important to adhere to local electrical codes and standards when designing a TNS earthing system. These codes and standards will specify the minimum requirements for earthing systems in the area, including the materials that can be used, the size of the earth conductor and earthing electrode, and the earthing resistance limits. For India, refer to IS 3043 (2018) – Code of Practice for Earthing and the National Building Code (2016) when designing the earthing systems.
2. Soil conditions: The soil conditions at the site of the electrical installation can have an impact on the design of the TNS earthing system. For example, if the soil is highly resistive (such as dry, sandy soil), it may be necessary to use a larger earthing electrode or to adopt special measures (such as using chemical earthing) to ensure that the earthing resistance is within acceptable limits.
3. Building materials: The materials used in the construction of the building can also affect the design of the TNS earthing system. For example, if the building is made of materials that are not conductive (such as concrete or brick), it may be necessary to use an earthing electrode with a larger surface area in order to ensure a low-resistance connection to the ground.
4. Size and complexity of the electrical installation: The size and complexity of the electrical installation will also impact the design of the TNS earthing system. Larger or more complex installations may require a more robust earthing system with a larger earth conductor and earthing electrode, and may also require additional protective devices (such as circuit breakers or fuses).

Components of a TNS Earthing System

The main components of a TNS (TN-S) earthing system include:

1. Earth conductor: This is a conductor (usually made of copper or aluminium) that is used to connect the electrical installation to the ground. In a TNS earthing system, the earth conductor (S) is connected to a metallic structure (such as a metal water pipe or metal rod) that is buried in the ground.
2. Neutral conductor: This is a conductor (usually made of copper or aluminium) that is used to connect the electrical installation to the neutral point of the electrical supply. In a TNS earthing system, the neutral conductor (N) is connected to the electrical supply.
3. Live conductor: This is a conductor (usually made of copper or aluminium) that is used to carry electrical current from the electrical supply to the electrical installation. In a TNS earthing system, the live conductor (T) is connected to the electrical installation.
4. Earthing electrode: This is a metallic structure (such as a metal rod or water pipe) that is buried in the ground and used to provide a low-resistance connection to the earth. In a TNS earthing system, the earth conductor (S) is connected to the earthing electrode.
5. Protective devices: These are devices (such as circuit breakers or fuses) that are used to protect the electrical installation from overcurrent or short circuit conditions.
6. Wiring: This is the conductor (usually made of copper or aluminium) that is used to connect the various components of the electrical installation.

TNS Earthing Installed in a Building/Structure

The installation of a TNS (TN-S) earthing system in a building or other structure typically involves the following steps:

1. Design: The first step in installing a TNS earthing system is to design the system in accordance with relevant electrical codes and standards, and taking into account the size and complexity of the electrical installation, the soil conditions at the site, and the materials used in the construction of the building.
2. Installation of earthing electrode: The earthing electrode is a metallic structure (such as a metal rod or water pipe) that is used to provide a low-resistance connection to the ground. The earthing electrode is typically installed by digging a hole at the desired location and inserting the electrode into the ground.
3. Connection of earth conductor: The earth conductor is a conductor (usually made of copper or aluminium) that is used to connect the electrical installation to the earthing electrode. The earth conductor is typically installed by running it from the electrical installation to the earthing electrode and connecting it to the electrode using a suitable connector.
4. Connection of neutral conductor: The neutral conductor is a conductor (usually made of copper or aluminium) that is used to connect the electrical installation to the neutral point of the electrical supply. The neutral conductor is typically installed by running it from the electrical installation to the main electrical panel and connecting it to the neutral point of the electrical supply.
5. Connection of live conductor: The live conductor is a conductor (usually made of copper or aluminium) that is used to carry electrical current.

Potential Hazards associated with a TNS Earthing

1. Electrical shock: If the TNS earthing system is not functioning properly, there is a risk of electrical shock for people using the electrical installation. This can be caused by a variety of factors, such as a damaged earth conductor or earthing electrode, or a failure of protective devices (such as circuit breakers or fuses). To mitigate this risk, it is important to regularly inspect and maintain the TNS earthing system, and to ensure that it is properly designed and installed in accordance with relevant electrical codes and standards.
2. Fire: If the TNS earthing system is not functioning properly, there is a risk of electrical fires caused by the accumulation of electrical current in the electrical installation. To mitigate this risk, it is important to regularly inspect and maintain the TNS earthing system, and to ensure that it is properly designed and installed in accordance with relevant electrical codes and standards.
3. Corrosion: The materials used in a TNS earthing system, such as copper or aluminum conductors and metallic structures (such as metal rods or water pipes), can be prone to corrosion over time. This can affect the performance of the TNS earthing system and increase the risk of electrical hazards. To mitigate this risk, it is important to use corrosion-resistant materials when designing and installing a TNS earthing system, and to regularly inspect and maintain the system to ensure that it is functioning properly.

This is why it is critical to properly maintain any Earthing System that you implement for your structure.

Maintenance of Earthing System

There are several steps that you can take to properly maintain a TNS (TN-S) earthing system:

1. Perform regular inspections: It is important to regularly inspect the components of your TNS earthing system to ensure that they are in good condition and functioning properly. This should include checking the condition of the earth conductor, the earthing electrode, and any protective devices (such as circuit breakers or fuses).
2. Test the earthing resistance: The earthing resistance of a TNS earthing system should be tested periodically to ensure that it is within acceptable limits. This can be done using an earthing resistance tester.
3. Repair or replace damaged components: If any components of your TNS earthing system are damaged or not functioning properly, they should be repaired or replaced as soon as possible to ensure the safety and reliability of the electrical installation.
4. Follow proper procedures when making changes to the electrical installation: Any changes or modifications to the electrical installation should be carried out by a qualified electrician, and should be done in accordance with relevant electrical codes and standards.
5. Follow proper procedures when using electrical appliances: It is important to use electrical appliances in accordance with the manufacturer’s instructions and to unplug them when not in use.

How do I know if my property has a TNS Earthing System Installed?

There are several ways you can determine whether your property has a TNS (TN-S) earthing system installed:

1) Check the electrical panel: The electrical panel is typically located in a central location in the building, such as a utility room or basement. The panel will contain circuit breakers or fuses that are used to protect the electrical installation from overcurrent or short circuit conditions. The panel will also have a grounding terminal, which is used to connect the earth conductor (S) to the earthing electrode. If your property has a TNS earthing system installed, you should be able to locate the grounding terminal in the electrical panel.

2) Check the wiring: If you have access to the wiring in your property (for example, if you have exposed wiring in an unfinished basement or attic), you should be able to identify the earth conductor (S), neutral conductor (N), and live conductor (T). In a TNS earthing system, the earth conductor (S) will be connected to the earthing electrode, while the neutral conductor (N) will be connected to the electrical supply, and the live conductor (T) will be connected to the electrical installation.

3) Consult the property’s electrical plans: The electrical plans for your property should contain information about the earthing system that is installed. You can usually obtain a copy of the electrical plans from the property’s previous owner or the local authorities.

4) Consult a qualified electrician: If you are still unsure whether your property has a TNS earthing system installed, or if you have any concerns about the safety or reliability of the earthing system, it is a good idea to consult a qualified electrician. A qualified electrician will be able to inspect the electrical installation and determine the type of earthing system that is installed, as well as identify any issues or deficiencies that may need to be addressed. They will also be able to provide recommendations for any necessary repairs or upgrades to ensure the safety and reliability of the earthing system.

Conclusion

In conclusion, TNS earthing systems are a vital component of any electrical installation, and it is important to understand their role in ensuring the safety of people and property.

Axis can provide a range of services to help clients design and install a TNS earthing system, including:

1. Design and engineering services: Axis Electricals can provide expert design and engineering services to help clients develop a customised TNS earthing system that meets the specific requirements and characteristics of their electrical installation. This may include selecting the appropriate materials, sizing the earthing conductors, and selecting the most suitable earthing electrodes.
2. Hardware Supply: Axis Electricals can also provide the hardware and materials needed to design and install a TNS earthing system. This may include earthing electrodes, such as copper plates, rods, or pipes, as well as earthing conductors, protective conductors, bonding conductors, and other components.
3. Installation services: Axis Electricals can provide professional installation services to help clients install their TNS earthing system. This may include installing the earthing electrodes, connecting the earthing conductors, and installing any protective devices, such as circuit breakers or fuses.
4. Testing and verification services: Axis Electricals can provide testing and verification services to ensure that the TNCS earthing system is installed correctly and is functioning properly. This may include using specialised test equipment to measure the performance of the earthing system and identifying any issues that need to be corrected.

By providing both the hardware and the services needed to install the earthing system, Axis offers a complete solution to clients looking to design and install a TNS earthing system.