As fire safety requirements continue to rise across industries such as rail transit, data centers, commercial buildings, renewable energy, power distribution, and telecommunications, Low Smoke Zero Halogen (LSZH) cables have become the preferred choice for many critical applications. Compared with conventional PVC cables, LSZH cables produce significantly less smoke and release no halogen-containing corrosive gases during a fire, helping improve evacuation safety while reducing damage to equipment and infrastructure.
However, being LSZH does not make a cable immune to aging. Over years of service, cables may still experience sheath cracking, deterioration of insulation performance, loss of mechanical properties, and even insulation failure. While cable lifespan depends on factors such as design, manufacturing quality, installation, and operating conditions, LSZH materials—widely used for cable insulation and jacketing—play a critical role in determining long-term reliability.
Common Signs of Aging in LSZH Cables
As cables age, both the insulation and outer sheath gradually deteriorate. Typical failure symptoms include hardened or cracked jackets, moisture ingress, reduced insulation resistance, abnormal temperature rise, joint failures, and insulation failure. These issues can compromise power transmission reliability and may eventually lead to equipment downtime, short circuits, or other safety hazards.
In most cases, cable failures do not occur suddenly. Instead, they result from the gradual degradation of material properties. For example, small cracks in the outer sheath allow moisture and contaminants to penetrate the cable, accelerating insulation aging. Likewise, prolonged exposure to elevated temperatures causes continuous deterioration of both the mechanical and electrical properties of the materials, ultimately reducing the overall reliability of the cable system.
Long-Term Heat Exposure Accelerates LSZH Material Aging
Thermal aging is one of the most common causes of cable degradation. When a cable operates under overload conditions or is installed in environments with poor heat dissipation, heat generated by the conductor is continuously transferred to the insulation and jacket, exposing LSZH materials to elevated temperatures over extended periods.
Prolonged heat exposure causes oxidative degradation of the polymer matrix and changes in the material’s internal structure. As a result, the material gradually becomes harder and more brittle, and surface cracking may occur. At the same time, tensile strength, elongation at break, and electrical properties decline, reducing the cable’s ability to withstand mechanical and environmental stresses and increasing the risk of insulation failure.
For this reason, a high-quality LSZH compound should offer not only excellent flame-retardant performance but also superior thermal aging resistance, long-term thermal stability, and retention of mechanical properties throughout its service life.
Moisture Can Reduce the Reliability of the Insulation System
High-humidity environments—such as underground utility tunnels, metro systems, tunnels, ports, and coastal installations—can significantly accelerate cable aging. If the cable jacket is damaged or cable joints are not properly sealed, moisture may gradually penetrate the cable, leading to lower insulation resistance and degraded electrical performance.
For cables insulated with XLPE (Cross-Linked Polyethylene), long-term moisture ingress may also initiate water treeing, a degradation mechanism that gradually weakens the insulation. In medium- and high-voltage cables, severe water treeing can eventually develop into partial discharge and insulation failure. It is important to note that water treeing occurs in XLPE insulation rather than in the LSZH jacket itself.
Therefore, high-performance LSZH materials should not only provide low-smoke, halogen-free, and flame-retardant characteristics, but also feature low water absorption, stable dielectric properties, and excellent resistance to moisture aging. These properties help maintain jacket integrity, reduce the likelihood of moisture ingress, and improve long-term cable reliability in humid environments.
Mechanical Damage and Chemical Exposure Can Shorten Cable Life
Mechanical damage remains one of the leading causes of premature cable failure. Compression, excessive pulling, over-bending during installation, or accidental damage caused by later construction work can compromise the protective outer jacket, making it easier for moisture, dust, and corrosive substances to enter the cable and accelerate insulation degradation.
In chemical plants, coastal regions, and other harsh industrial environments, cable jackets may also be exposed to acids, alkalis, salt spray, and various industrial chemicals over long periods. If the jacket material lacks sufficient chemical resistance, it may become chalky, crack, or lose mechanical strength, ultimately reducing the cable’s long-term reliability.
For demanding applications, LSZH jacket compounds should combine excellent flame-retardant performance with strong abrasion resistance, impact resistance, chemical resistance, and flexibility to ensure reliable performance under challenging service conditions.
Material Compatibility Also Affects Long-Term Reliability
Cable joints are among the most common points of failure in cable systems. While installation quality is essential, material compatibility should not be overlooked. If joint materials differ significantly from the insulation or jacket in terms of thermal expansion, shrinkage, or mechanical properties, repeated thermal cycling can create stress concentrations that compromise sealing performance and insulation reliability.
In addition, poor-quality LSZH compounds may exhibit inadequate filler dispersion, unstable melt flow, or inconsistent shrinkage during processing. These issues can affect extrusion quality, complicate cable assembly, and increase the risk of long-term service failures.
Selecting LSZH materials with consistent processing performance and stable physical properties helps improve manufacturing quality while ensuring better compatibility with cable accessories.
How High-Quality LSZH Materials Improve Cable Reliability
For cable manufacturers, stable material performance is fundamental to producing reliable products. A premium LSZH compound should not only meet low-smoke, halogen-free, and flame-retardant requirements, but also deliver excellent thermal aging resistance, mechanical strength, electrical performance, moisture resistance, and processing consistency.
High-quality LSZH materials help maintain the mechanical and electrical integrity of cable insulation and jackets, slowing material degradation under prolonged exposure to heat, humidity, and demanding service conditions. This contributes to improved product consistency, enhanced reliability, and a longer service life.
In addition, LSZH tape can be used for cable wrapping, separation, and auxiliary structural applications, providing additional mechanical protection and structural stability while maintaining low-smoke and halogen-free performance.
As performance requirements continue to increase across the construction, rail, power, renewable energy, and telecommunications industries, more cable manufacturers are placing greater emphasis on material quality. Choosing reliable LSZH materials not only improves production efficiency and product consistency but also helps reduce field failures and extend cable service life.
Conclusion
The aging of LSZH cables is typically the result of multiple factors working together, including prolonged heat exposure, moisture, mechanical damage, chemical attack, and the long-term stability of the materials themselves. Among these factors, the performance of LSZH materials plays a vital role in determining how effectively the cable withstands thermal, environmental, and mechanical stresses throughout its service life.
For cable manufacturers, selecting high-quality LSZH compounds and LSZH tapes is essential not only for meeting flame-retardant, low-smoke, and halogen-free requirements, but also for improving thermal aging resistance, mechanical durability, and long-term operational reliability. These materials provide a safer, more durable, and environmentally responsible solution for modern cable systems used in buildings, rail transit, renewable energy, power distribution, and telecommunications.
Post time: Jun-29-2026