The choice between underground and overhead transmission lines involves a trade-off between several key factors:

Advantages of underground Lines:

• Aesthetics and Land Use: Underground lines are visually unobtrusive, making them ideal for urban areas or locations with scenic landscapes. The land above the cables can often be used for agricultural purposes or other development with some minor restrictions.

• Protection from Weather: Buried cables are shielded from extreme weather events such as strong winds, ice storms, and lightning, which significantly improves reliability and reduces outage frequency.

• Increased Safety: The risk of accidental contact with energized conductors is eliminated, and they pose no hazard to wildlife or low-flying aircraft.

Disadvantages of Underground Lines:

• Higher Cost: The initial installation and material costs for underground cables are significantly higher than for overhead lines. This is due to the extensive excavation, specialized cables, and complex cooling systems required.

• Repair Challenges: While less prone to faults, when a fault does occur, locating and repairing the damage can be more complex, time-consuming, and expensive than for an overhead line.

• Thermal Constraints: underground cables are more susceptible to heat buildup. Their current-carrying capacity (ampacity) is often limited by the ability of the surrounding soil to dissipate heat.