Professional Answer: For direct burial applications, cables must be specifically designed to withstand the harsh underground environment without the need for a conduit. The most common types are underground Feeder (UF-B) and Underground Service Entrance (USE). UF-B cable is a versatile cable for residential and commercial uses, featuring a solid plastic sheath that fully encases the conductors, making it highly resistant to moisture, corrosion, and sunlight. USE cable is typically used for bringing power from a utility transformer to a building, and it's built with a tough, waterproof, and abrasion-resistant jacket. Both are excellent choices for ensuring a durable and safe installation.