Why Choose UL3132 and UL3135 Silicone Rubber Wires for High-Temperature Applications?

1. Introduction1. 

As renewable energy expands and industries demand higher power density and safer equipment, traditional cable materials like PVC or cross-linked polyethylene (XLPE) are struggling to meet performance requirements under extreme conditions. Heat, humidity, confined spaces, and fluctuating currents are pushing cables to their limits.

In this context, silicone rubber high-temperature wires certified under UL758 standards have emerged as a preferred choice. Among them, UL3132 and UL3135 silicone rubber wires stand out thanks to their superior thermal endurance, flexibility, and electrical insulation properties. Widely used in renewable energy projects, industrial machinery, and modern appliances, these wires are tailored to perform in challenging environments where conventional cables fail.

2. Understanding the UL758 Standard

Global Recognition of UL Certification

UL (Underwriters Laboratories) is one of the most recognized safety certification organizations worldwide. Its standards are trusted benchmarks that assure product safety, quality, and performance. For the wire and cable industry, UL standards serve as a passport for international trade, giving manufacturers access to global markets.

What Is UL758?

Introduced in 2014 and updated in 2024, UL758 is a crucial standard within the UL system, specifically targeting Appliance Wiring Material (AWM). It covers wires and cables used inside electrical equipment, control panels, and electronic assemblies.

The standard defines:

• Acceptable conductor materials and sizes

• Insulation materials, including PVC and silicone rubber

• Electrical and mechanical performance criteria

• Comprehensive test methods (heat, flame, moisture, oil, chemical, and abrasion resistance)

By ensuring that cables meet stringent requirements, UL758 provides both end-users and manufacturers with confidence in product reliability.

3. The Role of UL758 in Critical Applications

UL758-certified wires are especially important in applications like Battery Energy Storage Systems (BESS), where cables face multiple environmental stresses:

• Inside battery compartments: wires must withstand constant high temperatures and high humidity, resisting thermal aging and moisture-related degradation.

• Outdoor installations: in renewable storage stations, cables endure UV radiation, freezing winters, heavy rainfall, and heatwaves. UL758-certified silicone cables maintain stable insulation and mechanical strength despite these challenges.

• Operational stresses: during frequent charging and discharging cycles, BESS wires experience rapid temperature fluctuations and mechanical stress. In high-power states, they must survive sudden surges of large currents without compromising safety.

UL758 ensures that cables like UL3132 and UL3135 remain dependable in such environments, reducing risks of downtime, fire hazards, and equipment failure.

4. What Makes UL3132 and UL3135 Unique?

Silicone Rubber Insulation

The core advantage of UL3132 and UL3135 wires lies in their insulation: silicone rubber. Unlike organic plastics, silicone rubber is built on a silicon-oxygen (Si–O) backbone, which has a much higher bond energy compared to carbon-carbon (C–C) bonds. This molecular structure grants silicone insulation exceptional stability under extreme conditions.

Key benefits of silicone rubber insulation:

• Thermal resistance: stable from -60°C to +200°C, with no hardening at low temperatures or softening at high heat.

• Flexibility: small bending radius, ideal for compact installations.

• Electrical insulation: reliable dielectric strength, preventing current leakage and breakdowns.

• Safety: flame retardant, low smoke, and halogen-free options available.

• Durability: resistant to oil, chemicals, and environmental aging.

Technical Highlights of UL3132 and UL3135

• Certified under UL758 AWM standards

• Temperature rating: up to 200°C

• Voltage rating: suitable for a wide range of equipment (details vary by type)

• Excellent softness, reducing risk of cracking during installation in tight spaces

5. Advantages Over Conventional Cable Materials

Why not simply use PVC or XLPE wires? The answer lies in performance.

Silicone rubber outperforms PVC and XLPE in almost every category relevant to renewable energy, industrial, and automotive sectors, especially where cables must operate continuously in extreme temperature fluctuations.

6. Applications of UL3132 and UL3135 Silicone Rubber Wires

Because of their superior thermal and mechanical properties, UL3132 and UL3135 wires are widely used in both consumer and industrial sectors:

Renewable Energy

• Solar PV systems and inverters

• Battery Energy Storage Systems (BESS)

• Wind turbine control panels

Industrial Equipment

• Motors, generators, and transformers

• Heating equipment and industrial ovens

• Control cabinets and switchgear

Household Appliances

• Electric ovens, microwaves, and heaters

• High-end kitchen appliances

• Refrigeration units with high-temperature wiring zones

Automotive and Transportation

• Engine compartments exposed to continuous heat

• EV battery modules and charging systems

• Wiring harnesses requiring flexible high-temperature solutions

Other Advanced Industries

• Aerospace wiring in high-altitude environments

• Medical equipment requiring clean, heat-resistant insulation

• LED lighting and power electronics

7. Choosing Between UL3132 and UL3135

Although both are silicone rubber high-temperature wires under UL758, there are differences in their specifications:

• UL3132: typically used for smaller conductor sizes and lower voltage applications where flexibility is critical.

• UL3135: designed for slightly larger conductors and higher current loads, making it suitable for industrial equipment and power-intensive systems.

Selection Guide:

• For compact spaces requiring easy installation → UL3132

• For higher power density and durability → UL3135

EPC contractors, equipment manufacturers, and industrial users should evaluate conductor size, current requirements, and installation environments when making a choice.

8. Conclusion

The shift toward renewable energy and high-performance electrical equipment demands cables that can endure extreme heat, humidity, and operational stress. Traditional PVC and XLPE wires no longer provide sufficient safety and longevity in these demanding conditions.

UL3132 and UL3135 silicone rubber wires, certified under UL758, offer the perfect balance of thermal stability, flexibility, electrical insulation, and international compliance. They are particularly valuable for BESS projects, industrial manufacturing, and automotive applications, where reliability is non-negotiable.

For engineers, EPC contractors, and manufacturers seeking safe, durable, and globally certified high-temperature wires, UL3132 and UL3135 are the ideal solutions. Partnering with a professional supplier ensures consistent quality, compliance with global standards, and long-term performance in critical applications.