Which type of service-entrance conductors are allowed to be contained in a cable tray?

The correct answer is MI Cable. This type of cable, which stands for Mineral Insulated Cable, is specifically designed for use in a variety of applications, including areas where it may be exposed to harsh environmental conditions. MI cable is often used where both flexibility and fire resistance are required.

Mineral insulated cables are constructed with a solid metal sheath that encases the conductors, providing excellent protection against physical damage and extreme temperatures. Due to its unique construction, MI cable can safely be contained in a cable tray without the risk of compromising the cable's integrity or performance.

In contrast, the other types of cables mentioned, such as NM Cable (Non-Metallic sheathed cable), MC Cable (Metallic-Sheathed cable), and UF Cable (Underground Feeder cable), typically have specific installation conditions that may restrict their usage in cable trays due to factors like exposure to moisture or lack of adequate physical protection against mechanical damage. Thus, MI cable stands out as the most suitable option for containment in a cable tray.