The manufacturing and fire resistance testing of fire-resistant power cables comply with relevant international and domestic standards. The International Electrotechnical Commission (IEC) standard IEC 331-1970 stipulates that cables must maintain normal operation for 3 hours under a flame at 750°C.
my country's national standard GB 12666.6, "Test Methods for Fire Resistance Characteristics of Wires and Cables," is equivalent to IEC 331 (1970), but divides the test into two categories, A and B: Category A requires a fire temperature of 950–1000°C for 90 minutes; Category B requires a fire temperature of 750–800°C for 90 minutes. The new draft of IEC 60331, submitted for voting by the IEC, still requires a fire temperature of 750–800°C for 3 hours. If this standard is adopted and equivalently adopted in my country, there will be no distinction between Category A and B for fire-resistant cables. my country's current national standard for fire-resistant cable products is GB/T 19666-2019. In addition, there are international standards such as the British standard BS 6387 for fire resistance testing methods.
