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Underground cables are laid it sufficient depth so as to
Minimize temperature stresses
Minimize effects of shocks and vibration due to passing of vehicles
Avoid being unearthed due to removal of soil
Both (a) and (b)
Minimize effects of shocks and vibration due to passing of vehicles
Underground cables are buried at a sufficient depth (typically 0.75m to 1.2m) primarily to provide a cushioning layer of soil that attenuates mechanical shocks and vibrations caused by heavy vehicular traffic. This depth also provides protection against accidental excavation and ensures a stable thermal environment for the cable insulation.
Underground cables are buried at a sufficient depth (typically 0.75m to 1.2m) primarily to provide a cushioning layer of soil that attenuates mechanical shocks and vibrations caused by heavy vehicular traffic. This depth also provides protection against accidental excavation and ensures a stable thermal environment for the cable insulation.
PsoilтАЛ=AFтАЛ тАФ Pressure distribution mechanism where burial depth increases the area (A) of force dispersion.
The soil acts as a mechanical buffer. When a load passes over the surface, the pressure is distributed through the soil layers such that the stress reaching the cable is within safe limits. Burial also prevents direct thermal fluctuations due to solar radiation and ambient temperature shifts.
Typical burial depth for LT cables is 0.75m and for HT cables is 0.9m to 1.2m.
Mechanical stresses caused by heavy traffic (compressive waves) are dissipated by soil particles.
Sufficient depth prevents accidental damage during routine surface maintenance.
Soil thermal resistivity determines the safe current-carrying capacity (ampacity) of the cable.
Protection from extreme surface temperatures
Resistance to mechanical vibration and shock
Low susceptibility to damage from overhead line hazards (storm, lightning)
Difficult to locate and repair faults
High cost of excavation and installation
Heat dissipation is restricted compared to air-laid cables
Urban power distribution
Crossing under roadways and railways
Areas where overhead lines are restricted for safety or aesthetics
Standard depth requirements are governed by the Indian Electricity Rules (IER) to ensure public safety.
Option A is partially correct regarding temperature but is secondary to the primary design goal of physical integrity.
Option C is a secondary benefit, as marking tapes are used to warn excavators even at proper depths.
B is correct тАФ burial at a sufficient depth ensures that the mechanical pressure and vibrations from surface vehicles are adequately dispersed and attenuated by the soil cover.
Always remember that in power system installation, 'Depth' serves as a dual-purpose parameter: managing thermal resistance (ampacity) and structural load protection.