Why can security cables maintain circuit integrity and ensure the operation of emergency equipment during a fire?
Publish Time: 2026-01-08
In densely populated or critical facilities such as high-rise buildings, subways, hospitals, and data centers, the reliability of the power system directly affects the success or failure of personnel evacuation, fire-fighting coordination, and emergency rescue in the event of a fire. Ordinary cables often melt rapidly, short-circuit, or even fuel the fire under high-temperature flames, leading to the paralysis of the entire electrical system. Security cables, however, can continuously supply power for tens of minutes to several hours in open flames exceeding 950°C, ensuring the normal operation of critical equipment such as fire pumps, emergency lighting, alarm systems, and elevator controls. This "perseverance in the face of fire" is not accidental, but rather the result of a combination of special material selection, structural design, and stringent standards.1. Fire-resistant mica tape: Constructing an insulation barrier under high temperaturesThe core of a security cable lies in the fire-resistant layer wrapped around its conductor, typically using synthetic mica tape or ceramicized silicone rubber composite materials. Mica is a natural silicate mineral with a melting point exceeding 1200°C, and it maintains excellent electrical insulation properties even at high temperatures. When a fire occurs, although the outer sheath may burn, the dense, ceramic-like insulation layer formed by the mica tape firmly encapsulates the conductor, preventing phase-to-phase short circuits or grounding breakdown. Even if the temperature rises to 950℃ and continues to burn for 3 hours, the cable can still maintain normal power transmission at its rated voltage, providing a "last glimmer of light" for life-saving passages.2. High-Melting-Point Metal Conductors and Stable Structural DesignSecurity cables mostly use high-purity annealed copper conductors, which not only have good conductivity but are also less prone to oxidation and brittleness at high temperatures. Some high-end products also incorporate copper alloy or tin plating to further enhance oxidation resistance. Simultaneously, the cable core uses a tightly stranded structure to reduce internal gaps and prevent flame penetration; the filler uses high-temperature resistant inorganic materials that do not produce flammable gases during combustion but instead form a heat insulation barrier, slowing heat conduction inward. This "multi-layered defense" structure effectively protects the mechanical and electrical continuity of the conductor in extreme environments.3. Low-Smoke Halogen-Free Sheath: Balancing Safety and Environmental ProtectionSecurity cables commonly use low-smoke halogen-free flame-retardant polyolefin or cross-linked polyethylene as their outer sheath. These materials are halogen-free and do not release toxic or corrosive gases such as hydrogen chloride during combustion. They produce extremely low smoke density, significantly improving visibility and breathing safety at fire scenes. More importantly, their flame-retardant mechanism is "endothermic decomposition + carbonization coverage," where the cable expands upon contact with fire to form a heat-insulating char layer. This inhibits flame spread and protects the internal fire-resistant layer from direct burning, providing double fire protection.4. Stringent Certification Ensures Real-World ReliabilitySecurity cables must pass internationally recognized testing. The fire resistance test simulates a real fire scenario: the cable is horizontally laid out and directly burned by a specified power blowtorch flame from below, while simultaneously applying rated voltage and mechanical impact. Only cables that do not experience short circuits or power interruptions throughout the entire test are considered合格 (qualified). This triple test of "fire + electricity + force" ensures the product's reliable performance in real disasters.5. Application Scenarios Determine the Value of LifeIn high-rise buildings, security cables are used in systems such as fire pump control lines, emergency broadcasts, and smoke extraction fans, ensuring that "water can come in, air can be expelled, and people can escape" during a fire. In subway tunnels, they ensure the operation of train emergency braking and evacuation guidance systems. In hospitals, they maintain uninterrupted power to life support equipment. In these scenarios, every minute of power continuity can potentially save countless lives.Security cables are not simply an upgrade of ordinary electrical wires; they are special power carriers with materials science as their shield, structural engineering as their armor, and life safety as their mission. They safeguard the flow of electricity in flames, essentially protecting humanity's last line of defense in the face of disaster. As building safety standards continue to rise, security cables have transformed from an "optional" to a "mandatory" choice, becoming a silent yet indispensable "lifeline" in modern urban infrastructure.
