Earthing

Have you ever experienced a mild shock when you touch certain appliances while in operating condition? Sometimes these shocks can be dangerous and can lead to major hazards. To avoid mishappenings, it is always advisable to have a proper earthing done to the building. This process of sharing the charges with the earth is called earthing. Earthing is a simple way for the leakage of current and hence protects the devices from electrical damage. Grounding is also a safety process that protects the entire power system from malfunctioning and is mainly used to balance the load when the electric system overloads.

Earthing is defined as “the process in which the instantaneous discharge of the electrical energy takes place by transferring charges directly to the earth through low resistance wire.”

Low resistance earthing wire is chosen to provide the least resistance path for leakage of fault current. Let us know more about earthing and its types in this article.

How is Earthing Done?

To ensure safety, earthing can be done by connecting the electrical appliance to earthing systems or electrodes placed near the soil or below the ground level.

The electrode or earthing mat equipped with a flat iron riser is installed under the ground level. It helps to connect all the non-current-carrying metallic parts of the equipment.

This picture below shows the earthing system incorporated into an electrical system.

When the overload current is passed through the equipment or when the fault occurs in the system due to the current, the fault current from the equipment flows through the earthing system. The earth mat conductors aid in raising the voltage value equal to the resistance of the earth mat multiplied by a ground fault and helps guard the equipment against overload current or fault current.

In homes, there shall be three types of wires, live, neutral, and earth. Live and neutral carry electric current from the power station and the earth is connected to the buried metal plate. Electric appliances like refrigerators, iron boxes, and TV are connected to the earth wire while operating. Hence, these devices are protected from the surge or faulty electrical supply. Local earthing is done near the electrical metre of the house.

Here is a video with animations to help you understand the process of Earthing

Types of Earthing

There are three types of earthing, they are:

• Pipe earthing
• Plate earthing
• Strip earthing

Pipe earthing is the best and most efficient way of earthing and is also easily affordable. Pipe earthing uses 38mm diametre and 2 metres length pipe vertically embedded in the ground to work as earth electrodes.

In plate earthing, an earthing plate made of copper or G.I. is buried into the ground at a depth more than 3 metres from the ground level. This earthing plate is embedded in an alternative layer of coke and salts.

Strip earthing is used in transmission processes. Strip electrodes of cross section not less than 25mm X 1.6mm of copper or 25 mm X 4mm of G.I. or steel are buried in horizontal trenches of a minimum depth of 0.5m.

Advantages of Earthing

1. Earthing is the safe and the best method of offering safety. We know that the earth’s potential is zero and is treated as Neutral. Since low equipment is connected to earth using low resistance wire, balancing is achieved.
2. Metal can be used in electrical installations without looking for its conductivity, proper earthing ensures that metal does not transfer current.
3. A sudden surge in voltage or overload does not harm the device and person if proper earthing measures are done.
4. It prevents the risk of fire hazards that could otherwise be caused by the current leakage.

Read more about the difference between earthing and grounding.

Watch the full revision of the chapter Magnetic Effects of Electric Current Class 10

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