5.Īdd the result of steps 3 and 4 to provide the total resistance. 4.Ĭalculate the soil resistance using the backfill dimensions and the soil resistivity. For a level ground deposit with zero lateral strain in the soil, the 'at-rest' coefficient of lateral earth pressure, K 0 is obtained. For multiple anodes the internal resistance is calculated using the single anode equation and the result is divided by the number of anodes. The maximum stable value of K is called the passive earth pressure coefficient, K p the passive earth pressure would develop, for example against a vertical plow that is pushing soil horizontally. Subtract the value calculated in step 2 from that calculated in step 1. 2.Ĭalculate the resistance between the backfill and the protected structure using the backfill dimensions and the resistivity of the backfill. The following procedure is recommended to determine the total resistance: 1.Ĭalculate the resistance between the anode and the protected structure using the anode dimensions and the resistivity of the backfill. Both the groundbed resistance, which is often called the internal resistance, and the soil resistance have to be added together to get the total resistance between the groundbed and the buried structure.
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