This code provides comprehensive guidelines for the design, installation, calculation, and measurement of electrical earthing systems. It covers the determination of earth fault currents, soil resistivity, selection and sizing of earth electrodes and conductors, and safety measures against electric shock.
Provides guidelines for design, installation, and maintenance of earthing systems for electrical installations to ensure safety and proper operation.
Quick Reference Values
minimum length of pipe or rod electrode2.5 m
minimum diameter of GI pipe electrode40 mm
minimum dimensions of plate electrode600 mm x 600 mm
minimum thickness of GI plate electrode6.3 mm
minimum thickness of copper plate electrode3.15 mm
maximum earth resistance large power stations0.5 Ohm
maximum earth resistance major substations1.0 Ohm
depth of burial of strip or conductor electrode0.5 m
Key Formulas
S = (I * sqrt(t)) / k — Minimum cross-sectional area of protective conductor (where I is fault current, t is operating time, k is material constant)
R = ρ / (2 * π * l) * ln(4l/d) — Earth resistance of a driven pipe/rod electrode
Practical Notes
Adding alternate layers of salt and charcoal around the electrode significantly lowers earth resistance but accelerates the corrosion of the electrode.
Always physically disconnect the earth electrode from the main electrical installation via the test link before measuring its individual earth resistance.
Plate electrodes are preferred for high fault current applications (like substations), while pipe or rod electrodes are generally sufficient for standard building earthing.