Difference between IEC 60331/60332 fire protection standards and flame retardancy standards
Thread Content
The customer’s requirements for the cable specified that it needed to meet both IEC 60331 and 60332 standards. The cable manufacturers’ quotes all stated that it is impossible to satisfy these two standards simultaneously, as the cable structure would differ in such cases. I have also examined these standards carefully; perhaps my understanding of the English versions is insufficient, as I have been unable to distinguish between the differences between them. Because they are both in “under fire condition”; one is a circuit test and the other is a single wire test. There are also differences in temperature and duration during testing. Why do some people say that one is a flame-retardant standard and the other is a fire-resistant standard?
NH stands for fire resistance; it features a layer of mica tape inserted between the polyvinyl chloride insulation and the copper conductor, so that in the event of an external fire, the flame is separated from the conductor, allowing power supply to continue normally for a certain period of time. However, its insulating material is the same as that of ordinary BV wires； ZR stands for flame retardancy, which means that flame-retardant materials are added to the polyvinyl chloride insulation, preventing the outer insulation from catching fire and allowing it to extinguish itself once the source of fire is removed. The principle is different, but still, NH has a higher grade. Don’t really understand it; found it on Baidu. . . .
From a practical perspective, the only difference lies in the time and temperature of the fire resistance test. It always seems to me that this concept of fire resistance or flame retardancy is defined by us in China; is there such a term used abroad? Is it the Ran family that sets the standards directly? Different temperatures and times determine whether there will be a mica-based fire-resistant layer. So I would like to ask, since flame resistance is provided by the insulation layer and both the inner and outer sheaths are made of insulating materials, what materials are used for these various components of a fire-resistant cable? If it is an insulating material, can it be considered equivalent to the same type of flame-retardant cable with mica tape added to it, thereby achieving fire resistance?