How many earthing rods or plate electrodes do you need, and how far apart?

[dhairyashil_2]

how to decide the number of earthing rod or plate electrodes..

What the distance btwen two rod to be maintained in prepairng layout

As per IS3043 and IEEE 80..

 

[Bobbywhy]

The Indian & International standards for grounding are IS 3043 & IEEE 80 respectively. The size of the ground conductor for grounding the screen of an XLPE cable depends on the calculated ground fault current of the system. The ground fault current depends on various factors like strength of the source, type of grounding (solid, resistive etc), impedance of the source & the ground fault path. To understand the concept fully it is recommended that you read IEEE 80.

Additionally, you may see:
http://electricalnotes.wordpress.com/abstract/abstract-of-is-code/is-3043/