EARTHING

​

IIMT College of Engineering

EARTHING

• What is Earthing?
• Purpose of Earthing?
• Method of Earthing?

Earthing

The process of connecting metallic bodies of all the electrical apparatus and equipment to the earth plate or earth electrode through a thick conductor wire (which has very low resistance) for safety purpose is known as Earthing or Grounding.

Purpose of Earthing:

​

• To save human life from danger of electrical shock or death.
• To protect buildings, machinery & appliances under fault conditions   ie. To ensure that all exposed conductive parts do not reach a dangerous potential.
• To provide safe path to dissipate lightning and short circuit currents.
• To maintain the voltage at any part of an electrical system at a known value so as to prevent over current or excessive voltage on the equipment. 
• To provide protection against static electricity from  friction.      

​

​

Earthing Electrode

It consisting of three basic components:

1. Earth Wire
2. Connector
3. Electrode

​

1. Plate Earthing

• In this type of earthing plate either of copper or of Galvanised Iron (G.I.) is buried into the ground at a depth of not less than 3 meter from the ground level.
• The earth plate is embedded in alternative layer of coke and salts for a minimum thickness of about 15cm.
• The earth wire is securely bolted to an earth plate with the help of bolt nut and washer made of copper, in case of copper plate earthing and of G.I. in case of G.I. plate earthing.

2. Pipe Earthing

• Pipe earthing is best form of earthing and it is cheap also.
• In this system of earthing a GI pipe of 2meters length is embedded vertically in ground to work as earth electrode.
• The earth wire are fastened to the top section of the pipe with nut and bolts.
• The pit area around the GI pipe filled with salt and coal mixture for improving the soil conditions and efficiency of the earthing system.
• It can take heavy leakage current for the same electrode size in comparison to plate earthing.
• In summer season to have an effective earthing three or four bucket of water is put through the funnel for better continuity of earthing.

3. Rod Earthing

• In this system of earthing a solid rods of copper or solid rod of GI or steel of length not less than 3 meters are driven vertically into the earth
• In order to increase the embedded length of electrode under the ground, which is some time necessary to reduce the earth resistance to desired value more than one rod section are hammered one above the other.
• This system of earthing is suitable for area which are sandy in character .
• This system of earthing is very cheap

​

4. Strip Earthing

• In this system of earthing strip electrode of copper or GI or steel are buried in horizontal trenches of minimum depth of 0.5m
• The length of buried conductor shall be sufficient to give the required earth resistance (about 0.5Ωto 1.5Ω)
• It shall however be not less than 15 m
• The electrode shall be as widely distributed as possible in a single straight or circular trenches radiating from a point
• This type of earthing is used in rocky soil because at such places excavation work for earthing is difficult.

​

​

5. Earthing through water mains

• In this type of earthing the GI or copper wire are connected to the water mains with the help of the steel binding wire which is fixed on copper lead.
• The water pipe is made up of metal, and it is placed below the surface of the ground, i.e. directly connected to earth.
• The fault current flow through the GI or copper wire is directly get earthed through the water pipe.

​

THANK YOU