This document discusses underground cables for electrical power distribution. It covers the construction of cables including conductors, insulation, metallic sheathing, bedding, armouring and serving. Common insulating materials like XLPE are described. Cables are classified based on voltage level. Methods of laying cables underground include direct laying, draw-in systems and solid systems. Potential cable faults include open circuits, short circuits and earth faults. Underground cables have advantages over overhead systems like better appearance, lower maintenance needs and fewer faults, but the installation costs are higher.