Fire-resistant cables and conditions of use
Fire-resistant cable refers to a cable that can maintain safe operation for a certain period of time in the case of flame burning. China's national
standard GB12666.6 (such as IEC331) divides the fire resistance test into two levels, A and B. The flame temperature of Class A is 950 ~ 1000
℃, and the continuous fire time is 90min. min, during the entire test period, the sample should withstand the rated voltage value specified by the
product. Fire-resistant cables are widely used in high-rise buildings, underground railways, underground streets, large power stations, and
important industrial and mining enterprises and other places related to fire safety and fire rescue, such as power supply lines and control lines for emergency facilities such as fire equipment and emergency guide lights.
Use conditions of fire-resistant cables:
1. AC rated voltage: U. / U (V series: 600 / 1000V, K series: 450 / 750V, B series: 450 / 750V).
2. Maximum long-term working temperature of the cable
(1) PVC insulation and sheath: both 70 ℃ and 105 ℃; XLPE insulation: 90 ℃;
(2) Fluorine plastic insulation and sheath: 220 ℃ and 260 ℃; fluoroplastic insulation and 105 ℃ flame-retardant PVC sheath: 90 ℃ and 125 ℃.
(3) Low-halogen and low-smoke flame retardant PVC insulation and sheath: 70 ℃; halogen-free and low-smoke flame retardant polyolefin insulation and sheath: 90 ℃ and 125 ℃.
3. Minimum ambient temperature:
(1) Flame retardant PVC insulation and sheath: fixed laying -40 ℃; non-fixed laying -15 ℃;
(2) Fluoroplastic insulation and sheath: fixed laying -60 ℃; non-fixed laying -20 ℃；
4. The safe laying temperature of the cable should not be lower than 0 ℃.
5. Fire resistance characteristics:
Conforms to the provisions of IEC331 Conforms to the provisions of GB12666.6
Flame temperature 750 ℃ Flame temperature 950 ℃ -1000 ℃ Flame temperature 750 ℃ -800 ℃
Burning time 3h Burning time 90min Burning time 90min
Cooling time 21h Additional voltage Rated voltage Additional voltage Rated voltage
Additional voltage Rated voltage Additional current 3A Additional current 3A
Additional current 3A Class A Class B
6. The recommended allowable bending radius for laying: unshielded, braided shielded cable should not be less than 6 times the outer diameter of the cable;
Steel tape armored cable should not be less than 12 times the outer diameter of the cable;
Fluorine plastic insulated and sheathed material cables should not be less than 8 times the outer diameter of the cable.