Soil resistivity is one of the most critical factors affecting earthing and grounding system performance and safety. In cold climates, the top-soil layers may be frozen during the winter or spring seasons, and resistivity may increase to as high as 10,000 Ω.m in the frozen soil layers. This can give rise to significant touch voltage hazards during an earth fault.

Design methods that reduce earth grid resistance, comparing relative effectiveness and practical limitations in grounding system design.

This article shows the effects of soil resistivity and thickness of layers on grid resistance for earthing systems in multilayer soils. Increasing the resistivity of soil layers tends to increase the grid resistance, no matter which soil layer that is. Increasing the thickness of any soil layer with high resistivity also increases grid resistance and if the soil layer thickness is increased for a low resistivity layer then the grid resistance will decrease. Software modelling is performed and the results are compared and shown to match well with those from CDEGS software.