Several problems needing attention when installing fire-resistant cables
The fire-resistant cable can still maintain the normal operation of the line for a period of time under the burning condition, that is to say, in case of fire, the fire-resistant cable will not burn at once, and it can still maintain the normal power supply for a period of time.
This characteristic determines that fire-resistant cables play an important role in modern cities and industrial buildings, because once a fire occurs, the power supply circuits of control, monitoring, guidance and alarm systems must maintain normal operation.
Main application occasions of refractory cables: fire-resistant cables are mainly used on the power supply circuits from emergency power supply to users' fire fighting equipment, fire alarm equipment, ventilation and smoke extraction equipment, guide lights, emergency power outlets, emergency elevators, etc.
Staff should pay attention to the following problems when installing fire-resistant cables: 1. When fire-resistant cables are used in cable tunnels, cable interlayers, or in flammable places such as oil pipes and oil depots, class A fire-resistant cable should be selected first.
In addition to these situations, and when the number of cables is small, Class B fire-resistant cables should be selected.
2, fire-resistant cables are mostly used as the power supply circuit of emergency power supply, requiring normal work in case of fire.
As the ambient temperature rises sharply during fire, in order to ensure the transmission capacity of the line and reduce the voltage drop, for the circuit with long power supply line and strictly limited allowable voltage drop, the cross section of the fire-resistant cable shall be enlarged by at least one gear.
3. Fire-resistant cables cannot be used as high temperature resistant cables.
4. In order to reduce the failure probability of cable joints in fire accidents, the number of joints should be reduced as much as possible during installation to ensure that the lines can work normally in fire.
If branch wiring is needed, fire prevention should be done for the joint.