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How long do cables last?

2022-09-29

Cables typically have a service life of 20 years. Some might argue that they can last longer—perhaps even beyond 20 years. Indeed, there are cables that exceed this lifespan. From a safety perspective, however, the design life of a cable is intended to be significantly longer than its actual operational lifetime.

　　Factors affecting cable lifespan:

　　1. External Damage: Over the past decade, economic development has been rapid, with regions across the country growing at an accelerated pace. This has led to more visible impacts on daily life and transportation—especially in today’s era of fast-paced economic growth. While it’s well-known that cables can be damaged by external factors, many cable failures are actually caused by mechanical damage.

　　2. Insulation Damping: Typically, most cables are buried underground or housed within underground drainage pipes. In many cases, substandard cable joints are installed under damp weather conditions, allowing water or steam to seep into the connections. Over time, this moisture, combined with the influence of the electric field, can lead to the formation of water trees—microscopic, tree-like structures that gradually degrade the cable's insulation strength, ultimately resulting in failures.

　　3. Chemical Corrosion: The cable is buried underground. When selecting the type of underground cable, the intended service life of corrosion-resistant cables is typically determined based on their resistance to corrosion. However, if these anti-corrosion cables are not buried underground, they may be affected by microorganisms present in the soil.

　　4. Long-term Load Operation: Cables heat up, leading to reduced insulation performance and increased susceptibility to aging, which can ultimately cause short circuits. Prolonged operation under overload conditions generates high temperatures that significantly accelerate insulation degradation. This is especially true during the hot summer months, when cable temperature rises dramatically, often resulting in breakdowns at weak points in the insulation. As a result, cable failures become particularly common during the summer season.

　　5. Abnormal Cable Joints: Cable joints are a weak link in cable lines and frequently experience failures caused by human error. During the installation of cable joints, improper crimping or insufficient heating by construction workers can lead to reduced insulation at the cable termination, potentially resulting in accidents.

　　6. Environmental Conditions and Temperature: The external environment and nearby heat sources where the cable is located can also lead to excessive cable temperatures, insulation breakdown, severe explosions, and fires.

　　7. Causes of Cable Aging and Natural Disasters: Each cable will be explained in detail, along with its typical lifespan. Cables gradually lose functionality if used beyond the period specified in the manufacturer’s instructions. In addition to human-induced factors, natural environmental hazards such as landslides, mudflows, and wildfires can also contribute to cable degradation.

　　Characteristics of flame-retardant cables, halogen-free cables, and fire-resistant cables:

　　1. Power cables

　　Flame-retardant cables (ZA, ZB, ZC): Effectively slow down flame spread and prevent fires from escalating. Thanks to their low cost, they are widely used as fire-resistant cables. Whether a single cable or an entire bundle is involved, these cables ensure that flames remain contained within a specific area when combustion occurs, thereby minimizing the risk of major fire-related disasters and significantly enhancing fire safety for cable systems.

　　2. Power cables

　　Halogen-free cable (WZD): Low-smoke, halogen-free cables contain no halogen materials, resulting in low combustion corrosion and toxicity. They produce minimal smoke, reducing damage to people, instruments, and equipment—and facilitating prompt fire rescue operations. While these cables offer excellent flame retardancy, corrosion resistance, and low smoke density, their mechanical and electrical performance is slightly lower compared to conventional cables.

　　3. Power cables

　　Fire-resistant cable (N, NH): Its function is to maintain normal operation and ensure the integrity of the circuit for a specified period. When burned, fire-resistant cables produce fewer acidic gas fumes, significantly enhancing their fire resistance and flame-retardant properties. Notably, during combustion, the cable continues to sustain the circuit's uninterrupted operation, even under conditions involving water spraying and mechanical impact.

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