Sometimes adding more ground rods and pipes will not do achieve anything to bring the floor resistance down in high resistivity areas. Especially sometimes, adding more ground rods will not likely do just about anything to create the resistance down (the resistance stays exactly the same).

An excellent idea of soil resistivity and related tests are essential. Some guidelines needs to be established for your soil testing. Similarly the testing and spacing to ascertain the soil resistivity with depth is very important particularly if deep grounding/earthing elements will probably be used.

A greater than acceptable ground resistance would modify the safe operation of power system. Several various methods was applied in earlier times to diminish the grounding resistance from the grounding system. Methods include enlarging the grounding/earthing grid, connecting the principle grounding grid with the external grounding grid, improving the burial depth from the grounding grid, utilizing natural grounding object like steel foundations of structures, adding long vertical grounding electrodes or pipes, and changing the soils throughout the grounding grid with low resistivity materials and chemicals.

These techniques are suitable for different geographical situations but that does not mean they're going to work with no correct soil resistivity testing or proper evaluation and without collection of acceptable data to warrant their application. In reality, in a specific soil environment, two or more methods can be considered to decrease the grounding resistance effectively.



The technique to include deep vertical grounding electrodes to the grounding grid is very efficient at substations with small area. This technique can utilize low-resistivity soil layer and get rid of the high resistivity soil close to the surface afflicted with freezing and occasional temperature. To be able to limit the grounding resistance, the explosive grounding technique was proposed to lower the grounding resistance of grounding grids in high resistivity area. The evaluation of the explosive grounding technique as with every grounding technique is also suffering from cost.

One efficient strategy to limit the earthing resistance of substation is to apply deep ground wells electrodes. Several kinds of deep ground wells exist: For instance it is possible to drill 150 mm ground well and go 50 meters to 85 meters deep or maybe more in your yard unless you reach moist soil ground water or limestone... The soil well is filled with bentonite material and non-corrosive material to further improve resistivity.

In order to do such a grounding you need and to depend on enhanced or maybe more advanced grounding enter in to calculate correctly the grounding resistance since programs including ETAP or SKM would not have the mandatory capability to do these calculations because the grounding resistance from the equivalent model is not easily calculated. The grounding resistance of an deep ground well might be calculated by numerical analysis program according soil model. The SES application can be used.

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