Experimental characterization of contact resistance of desert soil with waste-enhancement materials in grounding systems

This study aims to investigate how the electrical-resistivity of different soils and grounding enhancement-materials is influenced by water-content and the dehydration under ambient and high-constant temperatures. The used enhancement-materials were extracted from surrounding wastes in Egyptian desert. First, waste enhancement-materials, their developed-mixture and soil samples were prepared for experimental testing. The contact-resistance between soil and enhancement-material was measured by using a designed soil-box. It was observed that adding a wood-ash as an interface-layer between the soil and enhancement-materials decreased significantly the contact-resistance. The developed-mixture and wood-ash demonstrated highest water-content retention when compared against the other enhancement-materials. This maintains their resistivity values low to serve for grounding purpose. The wood-ash has the smallest grain–size diameter among the enhancement-materials. This is why it ensures effective contact between the soil and enhancement-materials in grounding systems. The effect of varying injected-current through the soil-box on the resistance values of soils and enhancement-materials is also investigated. Finally, the effectiveness of using of these materials in reducing the resistance-to-ground of a practical copper rod buried into desert soil is evaluated.