Designers should consider the following points when selecting fire-resistant cables based on their specific characteristics:
(1) Class A fire-resistant cables should be the primary choice when cables are installed in densely packed cable tunnels or cable mezzanines, or in flammable areas such as those near oil pipelines or oil depots. Class B fire-resistant cables may be used in situations other than those mentioned above, provided the number of cables is limited.
(2) Fire-resistant cables are primarily used for emergency power supply circuits and must remain operational during a fire. Since ambient temperatures rise sharply during a fire, the conductor cross-section should be increased by at least one standard size for long supply circuits with strict allowable voltage drop limits; this ensures sufficient transmission capacity and minimizes voltage drop.
(3) Fire-resistant cables should not be used as high-temperature cables.
(4) To reduce the likelihood of cable joint failure during a fire, the number of joints should be minimized during installation to ensure the circuit continues to function properly. If branch connections are required, the joints must be properly treated with fire-resistant measures.