cableresistance

Cable resistance, also known as ohmic resistance in conductors, is the opposition that a cable presents to the flow of electric current. It is a fundamental property that influences power losses, voltage drop, and heating in electrical systems. The resistance of a cable depends on the resistivity of its material, its cross‑sectional area, and its length, as expressed by the formula R = ρL/A. Copper and aluminium are common conductors, with copper having a typical resistivity of about 1.68 × 10⁻⁸ Ω·m at 20 °C. Temperature also affects resistance; for many conductors it increases by roughly 0.393 % per degree Celsius for copper. Insulation, sheathing, and the presence of multiple conductors can modify the effective resistance through parallel paths or additional contact resistances.

Accurate knowledge of cable resistance is essential for designing power distribution, grounding, and protective devices. Excessive resistance leads to voltage drop, reducing the efficiency of electrical systems, and can cause overheating and damage to components. Engineers mitigate these effects by selecting cables with appropriate cross‐sectional areas, using materials with lower resistivity, and accounting for temperature coefficients in the design. Measurement methods include the Kelvin (four‑wire) technique, which eliminates lead resistance, and the use of specialized test rigs that can simulate operating temperatures and lengths. These practices help ensure that cables meet performance and safety standards while maintaining energy efficiency.