Several issues need to be paid attention to when installing fire-resistant cables
The refractory cable can still maintain the normal operation of the line for a period of time under burning conditions, that is to say, in the event of a fire, the refractory cable will not burn at once, and it can still maintain normal power supply for a period of time. This characteristic determines that fire-resistant cables play an important role in modern urban and industrial buildings, because once a fire occurs, the power supply circuits of control, monitoring, guidance and alarm systems must maintain normal operation.
The main use occasions of fire-resistant cables:
Fire-resistant cables are mainly used in power supply circuits from emergency power sources to user firefighting equipment, fire alarm equipment, ventilation and smoke exhaust equipment, guide lights, emergency power sockets, and emergency elevators.
When installing fire-resistant cables, workers need to pay attention to the following issues:
1. When the fire-resistant cable is used in cable-intensive cable tunnels, cable interlayers, or in flammable places such as oil pipes and oil depots, Class A fire-resistant cables should be selected first. Except for these cases, and when the number of cables is small, class B fire-resistant cables should be used.
2. Fire-resistant cables are mostly used as the power supply circuit of emergency power supply, and are required to work normally in case of fire. Since the ambient temperature rises sharply during a fire, in order to ensure the transmission capacity of the line and reduce the voltage drop, the cross-section of the fire-resistant cable should be enlarged by at least one level for a circuit with a long power supply line and a strictly limited allowable voltage drop.
3. Fire-resistant cables cannot be used as high-temperature cables.
4. In order to reduce the failure probability of cable joints in a fire accident, the number of joints should be minimized during installation to ensure that the line can work normally in a fire. If branch wiring is required, fireproof treatment should be performed on the joints.