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Examoogle • User • info@examoogle.com • EE-2024-8821
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Which type of material is used to make a rod for rod earthing?
Iron
Steel
Copper
All of above
All of above
Quick Summary: Rod earthing utilizes a metallic rod driven vertically into the earth to provide a low-resistance path for fault currents. Materials like iron, steel, and copper are used depending on soil resistivity, corrosion factors, and mechanical strength requirements.
Rod earthing utilizes a metallic rod driven vertically into the earth to provide a low-resistance path for fault currents. Materials like iron, steel, and copper are used depending on soil resistivity, corrosion factors, and mechanical strength requirements.
R=2πLρln(d4L) — Resistance of a rod electrode in homogeneous soil
The rod functions as an electrode where the resistance to earth R=2πLρln(d4L) depends on soil resistivity (ρ), rod length (L), and diameter (d). By increasing the depth, the rod accesses lower resistivity soil layers, enhancing the grounding efficiency. Metallic rods are chosen to withstand the impact forces during driving into the ground and to resist chemical corrosion.
Rod earthing is effective in areas with sandy or loose soil where deep penetration is possible.
Copper rods offer excellent conductivity and corrosion resistance but are expensive.
Galvanized iron (GI) and steel are common due to cost-effectiveness and high structural strength.
The resistance of the electrode is inversely proportional to the length of the rod driven into the soil.
Requires very small space for installation.
Economical compared to plate or pipe earthing in suitable soil conditions.
Cannot be used in hard rocky strata where driving a rod is difficult.
Susceptible to corrosion over long periods, especially in acidic or alkaline soils.
Residential building grounding systems.
Transmission line tower grounding.
Lightning arrester installations.
BIS codes (IS 3043) specify minimum diameters for rods to ensure mechanical integrity during installation.
Galvanizing provides a protective zinc coating to steel rods, significantly increasing service life in aggressive soil conditions.
D is correct — Rod earthing electrodes are manufactured from various conductive metallic materials like iron, steel, or copper to suit soil conditions and mechanical requirements.
Always remember that while copper provides the lowest resistance, GI and steel are preferred in many Indian installations for their superior mechanical strength during the 'driving' process.