In almost every electrical installation made, earthing is used. The earthing system, also known as the grounding system, is a circuit connecting parts of the electrical system to the ground. The earthing system thus regulates the conductors with respect to the earth’s conducting surface. Hence, the term, ‘earthing’ is also quite appropriate and indicative.
Why is an Earthing Necessary?
Earthing is an important component of electrical systems because of the following reasons:
- It keeps people safe by preventing electric shocks
- It prevents damage to electrical appliances and devices by preventing excessive current from running through the circuit
- It prevents the risk of fire that could otherwise be caused by current leakage
Advantages of earthing
From a technical perspective, earthing has some excellent advantages, resulting it in becoming a mainstream practice in the electrical industry.
- The electrical system is related to the potential of the general earth mass and cannot reach a different potential. The potential of the earth is zero volts and is known as the neutral of the electricity supply. This helps in keeping the balance.
- Another advantage is that metal can be used in electrical installations without having to worry about conductivity. Though metal is a good conductor of electricity, proper earthing ensures that metal parts not meant to be used for current transfer can be included in the system. This is done by providing a separate path for this faulty current, enabling its immediate detection and stoppage.
- In cases of surges in the voltage, high voltages can pass through the electricity circuit. These kinds of overload can lead to damaging of devices and danger to human life. When earthing is installed with the electrical installations, the current is routed through a different path and does not affect the electrical system.
- An electrical circuit has to be connected together with a lot of attention to the kind of reactions each transformer may have in response to any action on the part of any other transformer. The earth is an ever-present conductive surface and helps configure these relationships between different electrical sources and makes them easier to handle.
Types of Earthing
Plate earthing requires a copper or galvanised iron to be buried vertically into the earth in an earth pit, dug more than 10 feet into the ground. These earth pits are then filled with charcoal and salt in alternate layers.
For pipe earthing, a pipe of galvanised steel is placed in the soil instead of a plate. The pipe is drilled with holes for connecting the earthing wires. The length and diameter of the pipe depends on the type of soil and the type of electrical installation. In this method as well, the earth pits are filled with alternate layers of charcoal and salt for inducing reactivity. Pipe earthing is the most common type of earthing.
Similar to pipe earthing, rod earthing requires the burying of a rod made of copper or galvanised iron. Electrodes are embedded in the soil and thus decrease the resistance of the earth as required.
For wire earthing, several horizontal trenches are dug. Strip electrodes are buried inside these trenches. These electrodes are made of copper, or galvanised iron or steel. Sometimes, round conductors are also used in the ground.
The Waterman method calls for the use of Waterman or galvanised GI pipes. These pipes are buried in the earth and earthing clamps are used to reduce the resistance for the electrical connection.
Irrespective of which method is used for earthing, it is important to ensure that the size of the device, depth of its burial, and its connection to the electrical installations is done with great care and after in-depth calculations in order for it to be effective.
Factors Affecting Earthing Installations
Several factors can play a role in the earthing installations. These factors will have to be taken into consideration for any kind of calculations made about the type of earthing, the kind of circuits required, and so on.
The kind of soil is important for determining the effectiveness of the earthing. The earth’s resistance, moisture level in the soil, salts in the soil, etc. will play a significant role in determining the way the earthing is made. The soil composition is also another factor that needs to be taken into consideration. For e.g., rocky soil has to be treated very differently to wet soil.
Apart from the soil, the location of the earth pit is important to determine how the installation should be done. If there are underground obstructions in the form of rock beds, then they will affect the installations.