What type of insulation surrounds conductors in Type MI cable?

Type MI (Mineral Insulated) cable is characterized by its use of refractory mineral insulation that surrounds the conductors. This type of insulation is typically made from materials like magnesium oxide (MgO) and is designed to withstand high temperatures and provide excellent electrical insulation properties.

The mineral insulation offers several advantages, including resistance to moisture, fire, and various chemical environments, making it particularly useful in demanding applications such as industrial settings, power generation, and certain types of building wiring where safety and durability are paramount. This type of insulation allows Type MI cable to maintain its integrity and functionality under extreme conditions, which is a key feature that distinguishes it from cables insulated with other materials.

In contrast, the other materials listed, such as polyethylene or thermoplastic, do not have the same thermal and physical properties and are not used for the same high-temperature applications as Type MI cable. Rubber insulation, while flexible, is also not suited for high-temperature and high-performance applications like the mineral insulation found in Type MI cable.