There are different types of cables that are buried directly underground, but they all need to have a certain level of protection to withstand the special requirements of the underground environment. These cables have a robust insulation and jacket that protects them from moisture, soil, and damage that may be caused by digging or other ground activities. The following are the main types of cables that can be buried directly underground:
- UF (Underground Feeder) Cables: UF cables are typically used in direct burial applications. They can be installed directly underground without conduit, but must be covered with at least 24 inches of earth. For residential installations in approved non-metallic raceways, the minimum cover can be reduced to 18 inches.
- USE (Underground Service Entrance) Cables: With rugged XLPE insulation and annealed soft bare copper conductors, they can withstand harsh conditions and are typically maintained and managed by utility professionals.
- Direct Buried Wire: This type of outdoor wire is designed to be buried underground, usually without conduit. Direct burial wire has distinctive characteristics including rugged insulation and flexibility for underground cable applications.
- Armored Cable: This type of cable has a metal jacket, such as steel tape or steel wire, wrapped around the internal conductors to increase mechanical strength and protect the cable from external damage.
Key Considerations:
- Follow local electrical installation codes and standards to ensure safety and compliance in cable laying
- Environmental conditions (soil type, water table, soil corrosivity, presence of chemicals, etc.)
- Maintenance and overhaul. The burial depth of cables, path planning, joint handling, etc., should take into account possible future maintenance and overhaul needs.
In practice, we should consider the above factors to select the most appropriate cable type and laying method. As long as they are installed correctly and in accordance with the electrical code, cables can run underground for many years. However, additional protective measures still need to be considered under certain conditions such as crossing roads, building foundations or areas that may be subject to mechanical damage.
