EARTHING

 EARTHING:

Generally earthing means non current carrying metallic part of electrical equipments should be earthed to avoid danger of human life.

GRID RESISTANCE:  

Grid resistance means in an industry or building the number of earth pits joined parallel together to get a minimum earth resistance value and the vale should be less than 1.0 Ohms acceptable in the industry.

PIT RESISTANCE:  

Individual pit resistance can vary according to the solid resistance and the value can be 5 Ohms or more than that.  But to get a minimum value all the pits should connect in parallel as grid.

EARTH PITS: 

Earth pits are generally used by using charcoal, salt and GI pipe of 3meters in length and 40mm diameter.

Another type of earth pits are generally used are the solid rod of copper driven straightway into the earth to get minimum value by driving to a depth of max. 6meters.

EARTH MEGGER:  

For measuring the earth resistance earth megger is used and the diagram given below how to measure the earth resistance.

Safe earth resistance:  

Generally earth resistance of the total grid should be less than 1.0 Ohms which is acceptable for safe operation in Industries.