Professional Answer:

There are several primary methods for laying power cables, each with its own advantages. The most common methods are:

1. Direct Burial Laying: This is a popular and cost-effective method where armored cables are placed directly into a prepared trench. The trench is typically lined with a layer of sand or soft soil for protection, and the cables are then covered with another layer of sand before the trench is backfilled. This method is often used in rural or open areas.

2. Draw-in System: This method involves installing pipes, ducts, or conduits in the ground first. Cables are then "drawn" through these conduits from manholes or access points. This system provides superior mechanical protection and allows for easier repairs, alterations, or additions to the network without re-excavating the entire route.

3. Underwater Laying: This specialized method is used for submarine power cables. It involves laying cables on the seabed or riverbed using a specially designed deep-sea vessel known as a cable layer. To prevent damage from anchors or fishing trawlers, the cables are often buried in trenches on the seafloor using high-pressure water jets.