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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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Moisture content in the soil _______________ the soil resistance.
increase
decrease
does not affect
none of the above
decrease
Quick Summary: Soil resistance is inversely proportional to its moisture content. As the water content in the soil increases, the electrolytic conductivity of the soil improves, which significantly lowers its overall electrical resistivity.
Soil resistance is inversely proportional to its moisture content. As the water content in the soil increases, the electrolytic conductivity of the soil improves, which significantly lowers its overall electrical resistivity.
R=AρL — where R is resistance, ρ is soil resistivity, L is length, and A is area.
ρ∝M1 — showing resistivity is inversely proportional to moisture content M.
Soil acts as a complex electrolytic medium where water serves as the solvent for dissolved minerals and salts. When moisture levels rise, these ions become mobile, facilitating easier current flow. This increase in ionic mobility effectively decreases the bulk resistance offered by the soil to grounding electrodes.
Dry soil is an electrical insulator with very high resistance.
Moisture provides conductive ions that facilitate ground current dissipation.
Soil resistivity is a critical parameter in the design of earthing systems for substations and lightning protection.
Other factors affecting resistance include soil composition (clay vs. sand), temperature, and salt content.
Improved safety by ensuring low-impedance path to ground.
Better protection for sensitive electronic equipment.
Seasonal moisture variation can cause unstable earthing performance.
Corrosion rate of grounding electrodes increases in moist soil.
Electrical grounding systems (Earthing).
Geophysical surveys for resource exploration.
Lightning surge protection systems.
Soil resistivity testing is mandatory under IS 3043 for grounding system design.
Option A is incorrect because increasing moisture facilitates current flow, thus reducing resistance.
B is correct — Moisture acts as an electrolyte in the soil, which increases conductivity and consequently decreases the soil resistance.
Always remember that for grounding purposes, 'lower' resistance is safer; moisture is a natural helper, while dry, rocky soil is a major engineering challenge.