Which type of conductor is used for direct burial of underground service entrance?

The correct choice for a conductor suitable for direct burial of underground service entrances is Type USE. This type of conductor is specifically designed and rated for direct burial in the ground, with insulation that is resistant to moisture and sunlight, making it ideal for outdoor applications where exposure to the elements is a concern.

Type USE (Underground Service Entrance) is often utilized in installations where the conductor may be buried directly without additional protection. Its robust construction enables it to withstand the conditions encountered underground, such as soil moisture and chemical exposure.

In contrast, other types of conductors, while useful for various applications, may not provide the same level of protection or suitability for direct burial. Type TW is typically used for general wiring in dry conditions, which doesn’t necessarily support direct burial without additional measures. Type XHHW is insulated for wet and dry locations but is often intended for above-ground or conduit installations rather than direct burial. Type UF is indeed rated for underground use; however, it is typically limited to specific applications and sizes not primarily designated for service entrances.

Overall, Type USE is the preferred choice for ensuring safety and performance in underground service entrance applications.