Which type of cable is allowed to be buried in a trench underground with stabilized sand for protection?

Which type of cable is allowed to be buried in a trench underground with stabilized sand for protection?

• A. Type NM cable
• B. Type SE cable
• C. Type MI cable
• D. Type UF cable

Answer: (C)

Type MI (Mineral Insulated) cable is designed with a robust construction that includes a core made of copper or aluminum conductors insulated with a mineral oxide, typically magnesium oxide, and encased in a seamless metallic sheath. This design makes MI cable highly durable and resistant to moisture, corrosion, and mechanical damage. When buried underground, it can withstand the pressure and conditions of the environment, including being surrounded by stabilized sand, which provides an extra layer of protection. In the context of the other cable types, Type NM (Non-Metallic Sheathed) cable is not suitable for direct burial as it cannot endure moisture and is generally used indoors. Type SE (Service Entrance) cable is designed for overhead or exposed installations and is not typically intended for direct burial applications. Type UF (Underground Feeder) cable, while designed for underground use, does not provide the same level of protection from external damage as MI cable does, especially in more challenging environments. The construction and materials used in MI cable make it the appropriate choice for installation in buried applications, ensuring longevity and safety in the electrical system it supports.

Type MI (Mineral Insulated) cable is designed with a robust construction that includes a core made of copper or aluminum conductors insulated with a mineral oxide, typically magnesium oxide, and encased in a seamless metallic sheath. This design makes MI cable highly durable and resistant to moisture, corrosion, and mechanical damage. When buried underground, it can withstand the pressure and conditions of the environment, including being surrounded by stabilized sand, which provides an extra layer of protection.

In the context of the other cable types, Type NM (Non-Metallic Sheathed) cable is not suitable for direct burial as it cannot endure moisture and is generally used indoors. Type SE (Service Entrance) cable is designed for overhead or exposed installations and is not typically intended for direct burial applications. Type UF (Underground Feeder) cable, while designed for underground use, does not provide the same level of protection from external damage as MI cable does, especially in more challenging environments.

The construction and materials used in MI cable make it the appropriate choice for installation in buried applications, ensuring longevity and safety in the electrical system it supports.