The fire-resistant cable can still maintain the normal operation of the line for a period of time under burning conditions, that is, 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.
Fire resistant cables are mainly used in power supply circuits from emergency power supply to user's fire-fighting equipment, fire alarm equipment, ventilation and smoke exhaust equipment, guiding lights, emergency power sockets, emergency elevators, etc.
The following issues shall be paid attention to when installing fire-resistant cables:
1. When fire-resistant cables are used in cable tunnels and cable interlayer with dense cables, or located near oil pipes, oil depots and other flammable places, Class A fire-resistant cables shall be selected first. Except for these conditions, and when the number of cables is small, Class B fire-resistant cables shall be selected.
2. Fire resistant cable is mostly used as the power supply circuit of emergency power supply, which requires normal operation in case of fire. As the ambient temperature rises sharply in case of fire, in order to ensure the transmission capacity of the line and reduce the voltage drop, the fire-resistant cable section shall be enlarged at least one gear for the circuit with a long power supply line and strictly limited allowable voltage drop.
3. Fire resistant cables shall not 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 shall be reduced as much as possible during installation to ensure that the line can work normally in fire. If branch wiring is required, fireproof treatment shall be done for the connector.
