Fire-resistant cables can still maintain the normal operation of the line for a period of time under burning conditions, that is to say, in case of fire, fire-resistant cables will not burn all at once, and it can still maintain the normal power supply for a period of time. This characteristic determines the fire-resistant cable in modern urban and industrial buildings plays an important role, because once the fire occurs, control, monitoring, guidance and alarm systems such as power supply circuit must maintain normal operation.
The main use of fire-resistant cable occasions:
Fire-resistant cables are mainly used in the emergency power supply to the user fire equipment, fire alarm equipment, ventilation and smoke exhaust equipment, guide lights, emergency power outlets, emergency elevators and other power supply circuit.
Staff need to pay attention to the following issues when installing fire-resistant cables:
1, when the fire-resistant cable is used in cable-intensive cable tunnels, cable mezzanine, or is located near the oil pipe, oil depot and other flammable places, should be the first choice of class A fire-resistant cable. In addition to these cases, and the cable configuration is less in number, should be selected class B fire-resistant cable.
2, fire-resistant cables are mostly used as emergency power supply circuit, requiring normal operation during fire. Due to the fire when the ambient temperature rises sharply, in order to ensure that the transmission capacity of the line, reduce the voltage drop, for the power supply line is longer and strictly limited to the permissible voltage drop of the circuit, the fire-resistant cable cross-section should be enlarged by at least one grade.
3, fire-resistant cable can not be used as a high-temperature cable.
4, in order to reduce the failure rate of cable joints in fire accidents, in the installation should minimize the number of joints to ensure that the line can work properly in the fire. If you need to do branch wiring, the joints should be well treated for fire protection.