Overhead power cables are cheaper to install and maintain than underground power cables. They are also quicker to fix whenever faults develop. However, they are more susceptible to damage, and many people do not like the way they look.
Some estimates put the costs of underground power cables at as much as four times the cost of the overhead option. This is the primary reason why most cables are overhead. But it is not just about the installation, as maintenance and repair is also cheaper with overhead lines. This is because faults and damage to the lines are easier to locate, so they are quicker to repair. This saves money and reduces the amount of time that homes and businesses are without power.
Overhead power lines also have a higher capacity than underground options, and they typically need fewer substations.
However, overhead power cables are exposed to the elements. In particular they can be damaged by high winds, or by falling trees or branches. This does not happen with underground cables, which get damaged less often than overhead lines. The biggest threat to underground cables is flooding, which means they are often regarded as unsuitable in some areas, such as those close to the coast. On the plus side, underground cables are invisible, so there is no aesthetic impact.