Types of Mineral Insulated Fire Cables

At present, the domestic fire cables are mainly divided into two categories: rigid mineral insulated fire cables and flexible mineral insulated fire cables. Rigid mineral fire cables include (BTTZ, BTTQ, BTTVZ, BTTVQ) and so on, while flexible mineral insulated fire cables (BTLY, BTTW, YTTW, RTTW, TBTRZ, BBTRZ) and others. Rigid mineral insulated fire protection cables and flexible fire protection cables are widely used in applications requiring high fire safety standards. Each type has its own characteristics, making them suitable for different installation environments and needs. Below,  Shenxing Cables will elaborate on the characteristics, structure, and application scenarios of these two types of cables.

I. Rigid Mineral Insulated Cable / BTTZ BTTQ BTTVZ BTTVQ

BTTZ Rigid Mineral Insulated Cable is a fireproof cable that meets national standards and exceeds the BS6387 standard. It has been widely used in the international market for nearly a century and has undergone extensive validation. It is recognized as a mature, high-performance cable with exceptional fireproof qualities. Compared to other fire-resistant cables, the BTTZ cable allows a reduction by one cross-section level, eliminating the need for a ground wire, which results in cost savings similar to those of ordinary fire-resistant cables.

The construction of mineral insulated cables consists of a metal copper conductor, magnesium oxide as insulation, and a seamless copper tube as the sheath. The outer layer can be further protected by adding polyvinyl chloride, especially in areas prone to copper corrosion or where aesthetic appeal is important. In building or underground areas, a halogen-free and low-smoke outer sheath may be added. The continuous working temperature of these cables can reach up to 250°C, and they can withstand temperatures ranging from 950°C to 1000°C for 3 hours. They can operate even at temperatures close to the melting point of copper (1083°C), with the melting point of magnesium oxide at 2800°C.

BTTZ Rigid Mineral Insulated Cable

Key Features of Rigid Mineral Insulated Cable

• Excellent fire performance

• Overload protection ability

• High current-carrying capacity

• High working temperature tolerance

• Waterproof, anti-corrosion, and explosion-proof

• Superior shielding performance

• Radiation resistance

• Long service life

• Compact external diameter and lightweight

• Environmentally friendly and safe

• High mechanical strength and bending performance

• Good grounding capability

Main Application Areas for Rigid Mineral Insulated Cables

• Public buildings: Hotels, hospitals, schools, libraries, and museums.

• High-temperature environments: Metallurgical, coke, and shipbuilding industries.

• Explosion-proof and fire-hazardous areas: Petrochemical industries, refineries, nuclear power plants, etc.

• Underground areas: Subways, tunnels, and underground warehouses.

• Transportation and traffic hubs: Airports, train stations, and ports.

Rigid Mineral Insulated Cable  - BTTVZ

II. Flexible Mineral Insulated Cable / YTTW / BTTW / RTTW

Flexible mineral insulated cables, such as BTTZ, offer fire protection standards similar to those of rigid cables. These cables are especially advantageous in overcoming some limitations of the BTTZ cable. The flexible cables can be customized according to the required length and are easier to install, eliminating the need for intermediate connectors. The comprehensive cost is relatively low, while still maintaining the fireproof and mechanical characteristics of mineral insulated cables.

Advantages of Flexible Fireproof Cables

• Excellent fire performance, exceeding GB12666.6 Class A and BS6387 standards for high-temperature endurance (650°C for 3 hours, 950°C for 3 hours).

• Long continuous length, up to 1000 meters for single-core and multi-core cables.

• Large cross-sections, with single-core cables reaching up to 1000mm² and multi-core cables up to 240mm².

• Flexible and can be coiled on cable trays, with a bending radius ≤ 20D (D is the cable's outer diameter).

• Smoke-free and non-toxic, with inorganic insulation materials that do not produce harmful gases when burning.

• High overload capacity, with sheath temperatures up to 105°C.

• Corrosion-resistant copper sheath that eliminates the need for external pipe protection.

• Superior shielding performance to prevent interference in control and information lines.

• Reliable safety performance for power supply in fire-fighting systems and equipment.

• Long service life, with resistance to aging and high temperatures, often exceeding a century of use under normal conditions.

• Simple installation process, similar to ordinary cables, with significantly lower overall cost compared to mineral insulated cables.

Structure of Flexible Fireproof Cable

• Conductor: Stranded copper wire with excellent bending characteristics.

• Insulation: High-temperature resistant, non-combustible inorganic insulation materials.

• Copper sheath: Copper material with good bending properties after special processing, used as a PE wire.

• Outer sheath: Low-smoke, non-toxic plastic material with excellent anti-corrosion properties.

Application Scope of Flexible Fireproof Cable

• Power supply for fire-fighting equipment in all types of buildings, including elevators and emergency lighting systems.

• Power supply for equipment and lighting systems in densely populated buildings.

• High-temperature environments: Steel mills, glass factories, and smelters.

• Flammable and explosive environments: Petrochemical, coal mining, and related equipment power supply.

• Special environments: Hospitals, food factories, and other facilities requiring high cleanliness standards.

• Power supply for critical equipment in power plants and nuclear power plants.

III. Isolated Flexible Mineral Insulated Cable (BTLY, BBTRZ, TBTRZ)

Building on the traditional BTTZ mineral insulated cable, we have developed the BTLY, BTLYQ, BTLV, and BTLVQ cables with aluminum sheath continuous extruded mineral insulation. These cables feature a round copper stranded conductor, pure gold mica tape insulation, and an aluminum metal sheath, significantly simplifying the copper pipe drawing process and reducing costs.

Isolated Flexible Mineral Insulated Cable - BBTRZ

Features of Isolated Flexible Mineral Insulated Cable

• Fire resistance: Meets BS6387 standards for fire performance, including resistance to flames, water spray, and mechanical impacts.

• Available in a variety of sizes and lengths, with no need for intermediate connectors.

• Waterproof and shockproof, with a high degree of anti-rodent and anti-termite protection.

• Explosion-proof capabilities for use in hazardous environments.

• Corrosion-resistant aluminum sheath, requiring no additional protective measures in most environments.

• High mechanical strength, able to function even under severe mechanical damage.

IV. Installation and Construction Methods

Installation of mineral insulated cables requires careful attention to the cable head production process. The insulation resistance should meet specification requirements, and special care should be taken when stripping the magnesium oxide to avoid moisture infiltration.

The process involves sealing the exposed wires with a brass sealing cup, applying sealing paste gradually to avoid air pockets, and using heat-shrinkable tubing to secure the cables. Always perform insulation resistance tests after installation to ensure the integrity of the cable.

V. Installation and Laying Precautions

When laying mineral cables, the production of cable heads is critical. The insulation resistance must meet specification standards. Proper quality control during the cable head production process ensures long-term reliability. Special attention should be given when handling multi-core cables to avoid phase connection errors.

Intermediate joints, such as those for BTTZ cables, include brass components and require careful handling to ensure reliable insulation. Special care must be taken during the joint assembly process to ensure optimal performance.

In conclusion, both rigid and flexible mineral insulated cables offer outstanding fire resistance and mechanical protection, making them essential components in various high-risk environments. The choice between these cable types should be made based on the specific requirements of the installation site and the performance needed.

China Leading Mineral Insulated Cable Supplier- Shenxing

If you have needs or questions about high temperature cables（-100℃~+1200℃），mineral insulated cables, please feel free to contact us by e-mail, you can also get free samples.

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