By Eileen Harvey
In modern industrial and commercial environments, tray cables have become indispensable for facilitating power, control and instrumentation wiring. Their versatility and reliability make them a preferred choice for a range of applications; however, one significant consideration arises when these cables are used in outdoor installations or in partially covered ceilings: Are tray cables suitable for exposure to direct sunlight?
The answer is affirmative, provided that the correct type of tray cable is selected. It is essential to recognize that not all tray cables possess the same characteristics, and their ability to withstand direct sunlight hinges on several factors, including the materials used, their ratings and the specifications set forth by the manufacturer. Understanding these nuances is crucial for ensuring optimal performance and longevity of the cable in challenging environmental conditions.
The importance of sunlight resistance cannot be overstated, as prolonged exposure to ultraviolet (UV) radiation can lead to material degradation, compromising the integrity and functionality of the wiring. The science behind UV degradation reveals that certain materials can break down when exposed to sunlight, leading to issues such as cracking, brittleness and eventual failure of the cable.
Why Sunlight Resistance Matters for Tray Cables
Outdoor environments, as well as indoor areas featuring skylights, expansive glass facades or even partial protective coverings, can significantly expose tray cables to harmful ultraviolet (UV) radiation. Over time, this exposure can lead to detrimental effects on the cables. Notably, the insulation and jacketing materials may experience cracking, fading or a loss of flexibility, which can compromise their protective qualities.
Additionally, prolonged exposure to sunlight can accelerate the degradation of the electrical properties of the cables, potentially increasing the risk of moisture ingress. This unwanted moisture can, in turn, lead to short-circuits or ground faults, posing serious safety hazards. Furthermore, the cumulative effects of UV radiation can trigger premature cable failures, resulting in unexpected downtime and costly repairs, which can significantly impact operational efficiency and budget management
Key Materials and Sunlight-Resistant Technology
Key materials used in the development of sunlight-resistant technology play a crucial role in enhancing the durability and longevity of various products exposed to prolonged sunlight. Innovations in materials science have led to the emergence of advanced polymers, coatings and additives designed specifically to withstand the harmful effects of UV radiation.
UV-Stabilized Insulation and Jacketing
Sunlight-resistant tray cables rely on advanced polymers that protect against long-term UV exposure and harsh outdoor conditions. Cross-linked polyethylene (XLPE) is a common choice for both power and control tray cables, providing excellent resistance to UV, heat and moisture. UV-stabilized PVC is another widely used material, with special additives that help prevent discoloration, cracking and premature aging in sunlight.
For more demanding environments, fluoropolymers such as FEP and PTFE are preferred because of their superior resistance to UV, extreme temperatures and chemicals. In addition, black sheathing is frequently specified since it typically contains carbon black, a natural UV blocker that significantly improves durability under constant sunlight.
Industry Certifications and Standards
Sunlight-resistant tray cables are governed by strict certifications that ensure durability and safe installation in outdoor environments. UL 1277 is one of the most important, requiring cables marked “Sunlight Resistant” or “SUN RES” to undergo testing for long-term UV exposure as well as physical and mechanical endurance. The National Electrical Code (NEC) also mandates this labeling for any cables intended for exposed runs, ensuring that installers and inspectors can readily identify compliant products. In addition to U.S. requirements, international standards from organizations such as CSA, IEC and IEEE may apply, particularly in large-scale or multinational projects where global compliance is critical.
Best Practices for Installing Tray Cables in Sunlight
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Check for UV Rating: Always confirm sunlight or UV resistance on the cable marking or datasheet before outdoor or roof installation.
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Prefer Black or Dark Jackets: These offer the highest natural UV protection.
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Correct Routing: Use outdoor-rated cable trays and fittings. Provide additional shielding in areas of extreme sunlight or mechanical hazard.
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Spacing and Support: Avoid tight bundling—ventilation helps maintain operational temperature.
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Direct Burial: If cables are also going underground, ensure “direct burial rated” in addition to sunlight resistance.
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Regular Inspection: In critical environments, periodic visual inspection for cracks or discoloration is wise.
Application Examples
Rooftop solar projects in locations such as Mumbai, Dubai and Singapore expose cables to direct sunlight throughout the day in hot climates. In these conditions, UV-resistant TC or XHHW-2 cables are recommended, typically with black jacketing to withstand both prolonged sun exposure and elevated temperatures.
Coastal chemical plants, including those in Kochi and Abu Dhabi, present a more complex challenge with constant exposure to sunlight, salt and corrosive chemicals. For these environments, fluoropolymer tray cables such as FEP or PTFE provide the highest level of protection, ensuring long-term reliability despite the harsh surroundings.
Infrastructure installations like highways and tunnels may require cables to be routed both indoors and outdoors. In such projects, use tray cables that are specifically marked for outdoor and sunlight exposure to ensure durability and safety across varied installation points.
Frequently Asked Questions (FAQs)
Q1: Can all tray cables be installed in direct sunlight?
A: No. Only tray cables labeled “Sunlight Resistant” or with a “SUN RES” or equivalent UV protection marking are certified for exposed installations. Standard tray cables without this rating will degrade quickly outdoors.
Q2: Is sunlight resistance the same as direct burial rating?
A: Not necessarily. Some tray cables are rated for both sunlight and direct burial, but always confirm each rating from manufacturer documents before use.
Q3: Which materials are best for sunlight-resistant tray cables?
A: XLPE and fluoropolymer (FEP/PTFE) are the gold standard for UV and weather resistance. Black PVC with UV-resistant additives is also common and effective.
Q4: What happens if a non-sunlight-resistant tray cable is used outdoors?
A: Cables can become brittle, crack, lose insulation and need frequent replacement—eventually leading to electrical hazards, system breakdown or even fires.
Tray cables can indeed be suitable for direct sunlight exposure, provided they’re specifically designed and marked for sunlight resistance. Choosing cables constructed from UV-stabilized XLPE, black PVC, or fluoropolymers ensures years of safe, reliable service in outdoor and high-UV environments. Always prioritize correct cable ratings, verify compliance with local electrical codes and follow installation best practices for optimal performance.
If you’re planning an outdoor, rooftop or exposed installation in India, the Middle East, Southeast Asia or any high-UV region, consult an experienced supplier and review both UV and other environmental ratings for robust, long-term results. For example, the TKD Tray Cable collection includes sunlight-resistant options built for industrial and outdoor performance, including black-jacketed and XLPE-insulated variants that meet UL and NEC standards.
