What is the model number of fire-resistant wires and cables with a Class A combustion performance rating?-Guangdong Yongyi Zhujiang Wire & Cable Co., Ltd. – A manufacturing enterprise specializing in the production of wires and cables.

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What is the model number of fire-resistant wires and cables with a Class A combustion performance rating?

2020-01-03

In the "Partial Amendment to the Code for Fire Protection in Building Design," the term "mineral-insulated non-combustible cables" has been revised to "fire-resistant wires and cables with a fire performance rating of Class A." So, what specific standards must "fire-resistant wires and cables with a fire performance rating of Class A" meet? Currently, which models available on the market can satisfy this Class A fire performance requirement?

The classification of the combustion performance of wires and cables shall comply with the provisions of the current national standard "Classification of Combustion Performance of Cables and Optical Fibers," GB 31247-2014. According to GB 31247-2014, a combustion performance rating of Class A essentially corresponds to non-combustible cables. The entire cable product and each of its components (excluding metallic materials) shall be tested separately using the test method specified in GB/T 14402-2007, "Determination of Burning Heat Value of Building Materials and Products." Only when both the total heat value of the entire cable product and the total heat values of all its components meet the classification criterion—total heat value PCS ≤ 2.0 MJ/kg—can the product be classified as Class A.

Although the test method appears simple, in practice, only the BTTZ (BTTQ) series of copper-core, copper-sheathed magnesium oxide mineral-insulated cables specified in GB/T 13033.1-2007 "Mineral Insulated Cables and Terminations Rated 750V and Below—Part 1: Cables" can meet the requirements. This is because the BTTZ cable uses highly compressed magnesium oxide as its insulation material; its material structure is simple and contains few impurities, thus enabling it to satisfy the total heat value requirement of PCS ≤ 2.0 MJ/kg. Currently, the RTTZ series of flexible corrugated copper-sheathed mineral-insulated cables specified in the national standard GB/T 34926-2017 "Mineral Insulated Corrugated Copper-Sheathed Cables and Terminations Rated 0.6–1 kV and Below with Mica Tape Insulation" cannot meet the total heat value requirement. This is due to the use of mica tape insulation and a low-smoke, halogen-free, high-flame-retardant protective layer, both of which contain adhesives and other volatile substances within the mica tape. As for other types of flexible mineral-insulated cables available on the market—such as NG-A (BTLY), BBTRZ, and HFTGB—they contain large amounts of combustible materials like plastics and rubber, making it even more impossible for them to meet the requirement.

In summary, the "Partial Amendment to the Code for Fire Protection in Building Design" effectively reclassifies mineral-insulated, non-combustible cables as single-grade A non-combustible cables of the BTTZ (or BTTQ) type. Consequently, all flexible mineral-insulated cables currently available on the market will no longer meet the fire protection requirements stipulated in the code.

We are a manufacturer of non-combustible cables that have passed the GB 31247-2014 Class A fire performance test conducted by the National Fireproof Building Materials Quality Supervision and Inspection Center.

What is a mineral-insulated, non-combustible cable?

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