As an important part of the electrical system, wire, cable and optical cable play an important role in the construction engineering. However, as electrical facilities, there are many fires caused by wires and cables. As the protective layer and insulation layer of wires and cables will use some rubber and plastic materials, in case of fire, the flame may spread along the trend of wires and cables and become the ignition source of fire. Therefore, flame retardant wire and cable, fire-resistant wire and cable, flame-retardant optical cable, fire-resistant optical cable these products have been developed.

In fact, China's requirements for flame retardancy and fire resistance of wires, cables and optical cables can be traced back to 2005, when China officially issued the general rules for flame retardant and fire resistant wires and cables. The standard classifies halogen-containing and halogen-free flame-retardant wires and cables for the first time, and makes clear requirements for their performance. "Flame retardant and fire-resistant cables: classification and requirements for flame retardant and fire-resistant cables with plastic insulation Part 1: flame retardant cables" and "requirements and marking for flammability of flame retardant products and components in public places" These two national compulsory standards have also been promulgated one after another. These two standards have made clear provisions on the flame retardant characteristics, smoke emission, smoke toxicity and so on of flame retardant wires and cables, which further improves the standard system of flame retardant wires and cables.

With the upgrading of technology and the emergence of new products, the standards of all kinds of flame retardant and fire-resistant wires and cables have been released one after another. Today, we will introduce the testing items of relevant products specified in the latest GB / T 19666-2019 "general rules for flame retardant and fire resistant wires, cables or optical cables" and SJ / T 2932-2016 "flame retardant PVC insulated installation wires and cables".

Test items of flame retardant and fire resistant wires, cables or optical cables

1. Classification of combustion characteristics: single flame retardant, flame retardant class A, flame retardant class B, flame retardant class C, flame retardant class D, halogen-containing, halogen-free, low smoke, low toxicity, simple fire resistance, fire resistance with mechanical impact, fire resistance with mechanical impact and water spray

2. Flame retardant performance test items: single flame retardant performance test, bundle flame retardant performance test, fire resistance performance test, halogen-free performance test, low toxicity performance test, water spray test, water spray test

3. Critical concentrations of gases produced by combustion: carbon monoxide, carbon dioxide, sulfur dioxide, nitrogen oxide and hydrogen cyanide

Testing items of flame retardant PVC insulated wires and cables

1. Service characteristics: number of cores, nominal cross-sectional area of conductor, rated voltage, long-term allowable maximum working temperature of conductor, minimum ambient static temperature, installation temperature, minimum bending radius;

2. Structure and material: structure evaluation, conductor quality, insulation quality, stranding mass flow, shielding quality, sheath quality and dimension measurement;

3. Electrical performance: electrical continuity of conductor and shield, DC resistance of conductor, spark test, voltage test, insulation resistance;

4. Mechanical and environmental properties: insulation core tear off test, mechanical properties (tensile strength, elongation at break) of insulation and sheath before and after aging, high temperature pressure test, thermal shock test, low temperature winding test, etc;

5. Combustion performance: vertical combustion test

At present, PVC wire and cable are the main wire and cable materials in China. The chlorine atoms in the molecular structure of PVC wires and cables can make them have effective flame retardancy, but the smoke and hydrogen chloride gas produced during combustion are toxic. How to detect PVC wires and cables to study high-quality flame-retardant and fire-resistant wires and cables has become the subject of relevant enterprises. Of course, in the actual production, we should strictly follow the relevant flame retardant and fire resistant wire and cable testing standards