Earthing, also known as grounding, is an essential aspect of electrical systems. It involves connecting electrical equipment or installations to the earth or ground to protect people, animals, and equipment from electric shock and damage. Earthing also helps in reducing electrical noise, improving signal quality, and preventing electromagnetic interference. There are several types of earthing systems available, and selecting the best type of earthing for a particular installation depends on several factors. This article discusses the different types of earthing systems and their respective advantages and disadvantages to help determine which type of earthing is best.
Plate Earthing
Plate earthing is a type of earthing system where a copper or galvanized iron plate of size 60 cm x 60 cm x 3.18 mm is buried vertically in the ground. A connection is made between the plate and the electrical system to be earthed using a copper wire. Plate earthing is suitable for areas with dry soil conditions and low soil resistivity. It is easy to install, cost-effective, and requires minimal maintenance. However, plate earthing can be ineffective in areas with high soil resistivity and where the soil is prone to corrosion.
Pipe Earthing
Pipe earthing is a type of earthing system where a hollow galvanized steel or PVC pipe is buried vertically in the ground. The pipe is filled with alternate layers of charcoal and salt to improve the conductivity of the soil around the pipe. A copper wire is connected to the top of the pipe, and the other end is connected to the electrical system to be earthed. Pipe earthing is suitable for areas with high soil resistivity and moist soil conditions. It is also suitable for installations that require high fault current carrying capacity. However, pipe earthing requires periodic maintenance to refill the charcoal and salt layers, and the installation cost is relatively high.
Rod Earthing
Rod earthing is a type of earthing system where a copper or galvanized steel rod of length 2.5 m to 3 m is buried vertically in the ground. A connection is made between the rod and the electrical system to be earthed using a copper wire. Rod earthing is suitable for areas with dry soil conditions and low soil resistivity. It is easy to install, cost-effective, and requires minimal maintenance. However, rod earthing can be ineffective in areas with high soil resistivity and where the soil is prone to corrosion.
Strip Earthing
Strip earthing is a type of earthing system where a copper or galvanized iron strip of size 25 mm x 3 mm is buried horizontally in a trench of depth 0.75 m to 1 m. A connection is made between the strip and the electrical system to be earthed using a copper wire. Strip earthing is suitable for areas with high soil resistivity and moist soil conditions. It is also suitable for installations that require high fault current carrying capacity. However, strip earthing requires a large trench for installation, and the installation cost is relatively high.
Chemical Earthing
Chemical earthing is a type of earthing system that uses a backfill compound to improve the conductivity of the soil around the electrode. The electrode can be a copper pipe, rod, or plate. The backfill compound is a mixture of bentonite, salt, and graphite powder that is poured around the electrode. The compound absorbs moisture from the soil, and the salt helps in reducing soil resistivity. Chemical earthing is suitable for areas with high soil resistivity and where the soil is prone to corrosion. It is also suitable for installations that require high fault current carrying capacity. However, the installation cost is relatively high.
Earth Mat Earthing
Earth Mat earthing is a type of earthing system where a conductive mat made of copper or aluminum is laid on the surface of the earth. The mat is connected to the electrical system to be earthed using a copper wire. Earth mat earthing is suitable for installations with limited space and where there is no possibility of digging trenches or installing electrodes. It is also suitable for installations that require high fault current carrying capacity. However, earth mat earthing can be ineffective in areas with high soil resistivity, and it requires periodic maintenance to ensure the mat remains conductive.
Combined Earthing
Combined earthing is a type of earthing system that uses a combination of different types of earthing systems to provide a reliable and efficient earth. For example, a combination of rod earthing and strip earthing can be used in areas with varying soil resistivity. The rods are used in areas with low soil resistivity, while the strips are used in areas with high soil resistivity. Combined earthing is suitable for installations that require high fault current carrying capacity and where there is a need for a reliable and efficient earth. However, combined earthing requires careful design and planning to ensure the different types of earthing systems work together effectively.
So, which type of earthing is best? The answer depends on several factors such as soil resistivity, moisture content, installation space, and fault current carrying capacity requirements. For example, in areas with dry soil conditions and low soil resistivity, plate earthing or rod earthing may be the best option. In areas with high soil resistivity and moist soil conditions, pipe earthing or strip earthing may be the best option. In installations with limited space, earth mat earthing may be the best option. In installations that require high fault current carrying capacity, chemical earthing or combined earthing may be the best option.
It is essential to note that selecting the best type of earthing is just the first step. Proper installation and maintenance of the earthing system are crucial for it to work effectively. The earthing system must be installed according to the relevant codes and standards and regularly inspected and tested to ensure its integrity. Faults in the earthing system must be promptly identified and rectified to prevent electric shock or damage to equipment.
In conclusion, selecting the best type of earthing system requires careful consideration of several factors such as soil resistivity, moisture content, installation space, and fault current carrying capacity requirements. Each type of earthing system has its advantages and disadvantages, and the best option depends on the specific installation requirements. Proper installation and maintenance of the earthing system are crucial for it to work effectively, and regular testing and inspection must be carried out to ensure its integrity.