1. Flame-retardant wire and cable should have flame-retardant properties. According to "Test method for burning wire and cable and cable" GB/T18380.3-2001, it can be divided into three flame retardant grades: A, B and C. .
The American Institute of Standards and Technology conducted comparative combustion tests on flame-retardant and non-flame-retardant wires. The following test results illustrate the importance of using flame-retardant wire and cable:
a. Flame-retardant wires can provide more than 15 times of escape time than non-flame-retardant wires;
b, the material burned by the flame-retardant wire is only 1/2 of the non-flame-retardant wire;
c, the heat release rate of the flame-retardant wire is only 1/4 of the non-flame-retardant wire;
d. The amount of toxic gas produced by combustion is only 1/3 of that of non-flame retardant products;
e, smoke production performance, flame retardant products and non-flame retardant products no significant difference.
2. Halogen-free low-smoke wire and cable
Halogen-free low-smoke wire and cable should have halogen-free, low-smoke and flame-retardant properties. The indicators are:
GB/T17650.2-1999 (halogen-free test) GB/T17651.2-1998 (low smoke test)
PH weighted conductivity minimum light transmittance
PH≥4.3 r≤10us/mm T≥60%
3. Fire resistant cable
a. Fire test index of fire resistant cable (fire temperature and time), "Test method for fire resistance of wire and cable" GB12666.6-90 is specified as: Class A 950 ~ 1000 ° C, 90 minutes; Class B 750 ~ 800 ° C, 90 minute. The IEC331-1970 standard specifies 750 ° C, 3 hours, which is equivalent to China's Class B standard. From the new draft of IEC60331, which was recently voted by the IEC, the fire supply temperature is still 750 ° C ~ 800 ° C, 3 hours. If this standard is passed, China will be equivalent, then the fire resistant cable will not be classified as A or B.
b. Fire-resistant wire and cable can be divided into fire-retardant fire-resistant wire and cable and non-flame-retardant fire-resistant wire and cable according to different non-metallic materials. The domestic products of fire-resistant wire and cable are covered with mica and the flame-retardant protective layer is the main body. Most of them are B-class products. At present, they can reach the A-class standard, such as special synthetic mica tape and mineral insulation (copper core copper sleeve, Magnesium oxide insulation, also known as MI) fire resistant cable. The mineral insulated fire-resistant cable has the characteristics of non-combustible, smokeless, corrosion-resistant, non-toxic, impact-resistant and spray-resistant. It is called fireproof cable. The fireproof performance is the most prominent among the fire-resistant wire and cable varieties, but the manufacturing process is more complicated and the price is higher. High, the manufacturing length is limited, the bending radius is large, the insulation is easy to get wet, and the section of 25mm2 and above can only provide single-core products. It must use permanent special terminal and intermediate coupling, which is more complicated to install and construct.