Mineral fireproof cable
Mineral fire-resistant cable, also known as mineral insulated cable or fire-resistant cable, is a type of cable that uses inorganic mineral materials as insulation and sheath. It has excellent fire resistance, high temperature resistance, non toxicity, and durability, and is widely used in situations that require extremely high safety and reliability.
Core definitions and standards
It is a general term for a type of cable, whose insulation and sheath materials are mainly composed of mineral powders (such as magnesium oxide, mica), completely different from traditional plastic (PVC/XLPE) or rubber cables. Internationally, it is commonly referred to as MI cable or mineral insulated cable.
According to the structure and materials, it is mainly divided into two categories, both of which comply with the highest level of fire protection standards (such as CWZ level of BS 6387 in the UK and A-level fire resistance of GB/T 19666 in China):
1. Rigid mineral insulated cable (traditional MI cable, copper sheathed magnesium oxide insulation)
This is the most classic and high-performance type.
Structure:
Conductor: High purity copper core.
Insulation: Highly compacted magnesium oxide powder.
Sheath: Seamless copper tube.
Features:
The highest fire rating: can sustain power supply for more than 3 hours under flames of 950 ° C-1000 ° C.
Completely inorganic: does not contain any organic materials, does not burn or smoke in flames, and is non-toxic.
High temperature resistance: Long term working temperature can reach 250 ° C, short-term or special models can reach 1083 ° C (the melting point of copper).
High mechanical strength: The copper sheath is sturdy, corrosion-resistant, explosion-proof, spray resistant, and resistant to mechanical damage.
Extremely long lifespan: The material is stable, and the design lifespan can reach several decades or even hundreds of years.
2. Flexible mineral insulated cable (modern improved type)
Structure:
Conductor: Multiple strands of thin copper wire twisted together to make it soft.
Insulation: wrapped with mica tape (high-temperature resistant inorganic mineral).
Metal sheath: Use copper strip welded longitudinal wrapping or aluminum sheath to make it bendable.
Outer sheath: Add a layer of low smoke halogen-free flame-retardant plastic sheath on the outermost layer to facilitate pipe penetration and provide additional protection.
Features:
Retaining excellent fire resistance: typically meeting the requirement of continuous power supply for 1.5-3 hours at 750 ° C-950 ° C.
Good flexibility: Similar to ordinary cables, easy to lay and bend.
Better moisture resistance: The structural design is more conducive to moisture resistance.
The installation process is relatively simplified, and the production of joints is more convenient.
Mineral fire-resistant cables are not an upgraded version of ordinary cables, but a completely different design concept of "safety redundancy" products. Its core value lies not in daily use, but in excellent survival ability and reliability under extreme fire conditions.
Pursuing ultimate safety, regardless of cost, installation conditions allow → Choose rigid mineral insulated cables.
Meet the highest fire safety standards, while requiring convenient construction and comprehensive cost → Choose flexible mineral insulated cables.
In architectural electrical design, it is often mandated to be used for the most important fire protection circuits.
