2. Malfunctions

2.1 Causes of defects

The various components of the networks are designed, built, and maintained to achieve the best balance between cost and the risk of failure. This risk is therefore not zero, and incidents or malfunctions can disrupt the operation of the facilities.

• Overhead power lines (see specialized articles in the "Equipment and Structures" section) are subject to atmospheric disturbances (lightning, storms, etc.). Certain regions, such as mountainous areas, are much more exposed than others to lightning, ice, or snow; depending on the year and voltage levels, lightning can account for 60 to over 80% of faults.

• Underground cables are exposed to external damage (from earth-moving...