Soil Resistivity Values for Different Types of Soil

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One key determinant of a good earthing installation is the soil resistivity of the soil where the earth electrode is installed. If you are involved  in earthing buildings and electrical installations, here is a list of the typical soil resistivity values for different types of soil that you might encounter:

Type of Soil Mean Value of Resistivity in Ωm
Swampy soil, bogs 1 - 30
Silt alluvium 20 - 100
Humus, leaf mould 10 - 150
Peat, turf 5 - 100
Soft clay 50
Marl and compacted clay 100 - 200
Jurassic marl 30 - 40
Clayey sand 50 - 500
Siliceous sand 200 - 300
Stoney ground 1,500 - 3,000
Grass-covered-stoney sub-soil 300 - 500
Chalky soil 100 - 300
Limestone 1,000 - 5,000
Fissured limestone 500 - 1,000
Schist, shale 50 - 300
Mica schist 800
Granite and sandstone 1,500 - 10,000
Modified granite and sandstone 100 - 600
Fertile soil, compacted damp fill 50
Arid soil, gravel, uncompacted non-uniform fill 500
Stoney soil, bare, dry sand, fissured rocks 3,000