Calculation of earth electrode
Calculation of earth electrode
(OP)
We have Indoor LV substation area of 600sqmm. We need to derive the required no of earth pits to be placed.
The main earthing conductor is 120Sqmm cu, sleeved, soil resistivity is 100ohm/m, minimum earth rod size to be used is 25mm dia 1200mm long, required minimum earth resistance 1 ohm .
Anyone can please help me out how to derive the no of rods based on area, soil resistivity when using the 120sqmm cu, cable as main earthing conductor.
The main earthing conductor is 120Sqmm cu, sleeved, soil resistivity is 100ohm/m, minimum earth rod size to be used is 25mm dia 1200mm long, required minimum earth resistance 1 ohm .
Anyone can please help me out how to derive the no of rods based on area, soil resistivity when using the 120sqmm cu, cable as main earthing conductor.






RE: Calculation of earth electrode
Schwarz, S. J., "Analytical expressions for resistance of grounding systems," AIEE Transactions on Power Apparatus and Systems, vol. PAS-88, pp. 910-919, June 1969.
RE: Calculation of earth electrode
Beware that rods is working in interconnected system and only will share a portion of the current injected in the earth. A starting point may be using the equations developed by S. Schwarz “Analytical expression for resistance of grounding systems,” AIEE Transactions on Power Apparatus and Systems, vol. 73, no. 13, part III-B, pp. 1011–1016, Aug. 1954. In addition, the IEEE Std 80-2000 contain portion of this subject on chapter 14.