1. Introduction
Solar energy has become a cornerstone of sustainable energy solutions worldwide. Central to the efficient and safe operation of solar installations is the reliability of their components—especially solar conduits, which protect wiring and ensure the proper transmission of electrical energy.
Ctube’ s solar conduits comply with this two main sets of standards, the International Electrotechnical Commission (IEC) standards, specifically IEC 61386-1: Conduit systems for cable management -Part 1: General requirements and the AS/NZS 2053.1: Conduits and fittings for electricalinstallations Part 1: General requirements.
And in this post aims to compare and contrast the IEC and AS/NZS standards for solar conduits. In fact, solar conduit can be made from a wide range of materials, and its main function is to protect wires and cables for solar photovoltaic power generation or for outdoor use in areas exposed to strong UV rays. In the following, we will explore key aspects such as technical specifications, testing methodologies.
2. Understanding IEC and AS/NZS Conduit Standards
2.1 The Role of Standards in Solar Conduit Systems
Standards play a crucial role in ensuring the safety, reliability, and efficiency of solar conduit systems. They provide guidelines for material selection, design, installation, and performance testing, helping manufacturers, engineers, and installers comply with regulatory requirements. Standardized solar conduits protect electrical wiring from environmental hazards such as UV radiation, temperature fluctuations, moisture, and mechanical impact, ensuring long-term functionality in solar power installations. In the following, we will make a explanation of AS/NZS 2053 and IEC 61386 standards.
2.2 AS/NZS 2053: Conduits and Fittings for Electrical Installations
An Australian/New Zealand Standard outlining requirements for conduits and fittings used in electrical installations. It categorizes conduits by material and design. Ensures conduits meet regional safety and performance criteria in Australia/New Zealand. Focuses on material types and mechanical properties.
Part 1 (2053.1): General requirements applicable to all conduit types.
Part 2 (2053.2): Rigid conduits and fittings made of insulating materials (e.g., PVC).
Part 3 (2053.3): Rigid conduits of fiber-reinforced concrete (used in harsh environments).
Part 4 (2053.4): Flexible conduits of insulating materials (for bending around obstacles).
Part 5 (2053.5): Corrugated conduits (flexible, ribbed design for easier cable pulling).
Part 6 (2053.6): Profile-wall, smooth-bore conduits (lightweight with a smooth interior).
Part 7 (2053.7): Rigid metal conduits (e.g., steel, for high mechanical protection).
Part 8 (2053.8): Flexible metal/composite conduits (e.g., stainless steel, for vibration-prone areas).
2.3 IEC 61386: Conduit Systems for Cable Management
An international standard (IEC) for conduit systems, emphasizing application-specific requirements. Provides global guidelines for conduit applications, focusing on installation environments (e.g., buried, flexible) and accessories.
Part 21 (61386-21:2002): Rigid conduit systems (e.g., PVC or metal for fixed installations).
Part 22 (61386-22:2002): Pliable conduit systems (semi-flexible, for moderate bends).
Part 23 (61386-23:2002): Flexible conduit systems (highly bendable, e.g., corrugated plastic/metal).
Part 24 (61386-24:2004): Underground conduit systems (resistant to moisture, corrosion, and soil pressure).
Part 25 (61386-25:2011): Conduit fixing devices (clamps, brackets for securing conduits).
2.4 Key Differences in Standardization Approach
While both IEC and AS/NZS standards aim to enhance solar conduit performance, their focus areas differ:
IEC standards emphasize universal applicability, making them suitable for a wide range of global installations.
AS/NZS standards integrate region-specific factors, ensuring conduits can endure Australia and New Zealand’s extreme environmental conditions.
3. Understanding Solar Conduit: Types, Materials, and Standards
Solar conduit is designed to house and protect the electrical cables that connect solar panels to inverters, combiner boxes, and other system components. Because solar installations are often exposed to harsh outdoor conditions—such as UV radiation, extreme temperatures, moisture, and physical stress—solar conduit must meet strict performance standards and be constructed from materials that can withstand these environmental challenges.
3.1 Relevant Standards for Solar Conduit
To ensure safety, durability, and compliance in solar power systems, solar conduit must meet several important standards. Here we just mention the common standard, if there is a regional standard to be followed, follow the regional standard.
UL 1703 – Covers the construction and safety of solar photovoltaic (PV) modules and panels.
UL 651 – Applies to rigid PVC conduit and fittings, ensuring they meet electrical and mechanical requirements.
UL 1660 – Covers non-metallic flexible conduit, including protection against moisture and UV exposure.
IEC 61386 – International standard for conduit systems for electrical installations.
NEC (National Electrical Code) – Provides guidelines for the proper use of conduit in solar installations, including grounding, support, and installation methods.
ASTM D1784 – Standard specification for the quality and properties of rigid PVC compounds used in conduit.
3.2 Types of Solar Conduit – Structural Properties
Rigid solar conduit is typically non-bendable and maintains a fixed shape, providing strong mechanical protection against physical impact, heavy loads, and extreme weather conditions. Its rigid structure makes it ideal for straight runs and exposed installations where stability and durability are essential. Because it cannot bend, installation often requires the use of fittings such as elbows and couplings to navigate corners or changes in direction.
Flexible solar conduit is bendable and designed to adapt to irregular paths, tight spaces, and complex layouts without the need for additional fittings. Its flexibility allows it to accommodate movement, vibration, and shifting surfaces, making it suitable for dynamic installations or areas with frequent structural changes. Despite its flexibility, it still provides strong protection against UV rays, moisture, and environmental stress.
3.3 Materials Used in Solar Conduit
Solar conduit is made from various materials, each suited for different applications.
PVC is lightweight, corrosion-resistant, and UV-stabilized, ideal for above-ground and underground use. UPVC is more rigid and durable, offering better chemical resistance.
Fiberglass is highly resistant to corrosion and UV rays while being lightweight and non-conductive.
Aluminum is corrosion-resistant and lightweight but less durable under heavy impact. Steel provides high strength and mechanical protection but is heavier and prone to corrosion without proper treatment.
HDPE is flexible, chemical-resistant, and suitable for direct burial. LSZH emits minimal toxic gases during a fire, making it ideal for safety-critical settings.
Nylon and polypropylene offer flexibility and chemical resistance for specialized applications.
4. Solar Conduit Match with the Standards and UV Tests
What has to mention is that the standards (AS/NZS 2053 and IEC 61386) don’t specifically talk about solar conduits or practical UV testing.
However, the AS/NZS 2053 standard has mentioned that it is possible to produce solar conduits under these standards by adding UV-resistant materials.
Experience has shown that the addition of 1.5 parts per hundred of resin of titanium dioxide will provide adequate protection against solar radiation for UPVC, and 2% of carbon black will provide adequate protection against solar radiation for plasticized PVC and polyethylene.
Because solar installations require exposed conduits to sunlight, UV resistance is critical. The manufacturers can use these standards as a base and add UV-resistant materials. And because the standards don’t cover it, so third-party testing might be necessary.
4.1 ISO 4892: Accelerated Weathering of Plastics
ISO 4892 is a globally recognized standard for evaluating how plastics degrade under simulated sunlight, heat, and moisture. It is divided into multiple parts, with ISO 4892-2 and ISO 4892-3 being most relevant to solar conduits.
ISO 4892-2 employs xenon-arc lamps to replicate the full spectrum of sunlight, including ultraviolet (UV), visible, and infrared (IR) wavelengths. These lamps closely mimic natural solar radiation, making this test ideal for materials used in outdoor solar installations. A typical cycle involves 102 minutes of UV exposure at 60°C followed by 18 minutes of water spray to simulate rain. This alternating stress evaluates critical parameters such as color fading, surface cracking, and gloss loss. For example, PVC conduits tested under ISO 4892-2 might show a 20% reduction in tensile strength after 1,000 hours, signaling the need for UV stabilizers like carbon black.
ISO 4892-3 uses UV fluorescent lamps (UVA-340 or UVB-313) to focus exclusively on UV wavelengths. UVA-340 lamps target 295–365 nm, matching the UV spectrum that reaches Earth’s surface, while UVB-313 emits shorter, more aggressive wavelengths (280–315 nm) for accelerated degradation. A common cycle includes 8 hours of UV exposure at 60°C and 4 hours of condensation at 50°C. This test is particularly useful for assessing polymer conduits in arid or high-UV regions, such as solar farms in Australia or the Middle East.
Both methods provide data on material longevity, helping manufacturers select UV-stabilized polymers like PVC-U or HDPE for solar conduits.
4.2 ASTM G154: Fluorescent UV Exposure of Non-Metallic Materials
ASTM G154 is a widely adopted standard in North America for evaluating UV resistance using fluorescent lamps. Unlike xenon-arc tests, it emphasizes cyclical exposure to UV light and condensation, mimicking day-night and weather patterns.
UVA-340: Simulates sunlight up to 365 nm, ideal for general outdoor applications.
UVB-313: Emits shorter, more intense UV wavelengths (280–315 nm) for accelerated testing, though it may overstress materials compared to real-world conditions.
A typical ASTM G154 cycle involves 4 hours of UV exposure at 60°C followed by 4 hours of condensation at 50°C. This alternating environment tests mechanical properties such as tensile strength retention and surface integrity. For instance, a polypropylene conduit might undergo ASTM G154 testing to ensure it retains 80% of its impact resistance after 500 hours—a key requirement for solar tracker systems exposed to constant movement and UV exposure.
Engineers often pair ASTM G154 with ISO 4892 to validate results across different UV spectra and humidity conditions.
4.3 Complementary Standards and Practical Considerations
ASTM D4329: Targets plastics with fluorescent UV lamps, measuring changes in elongation and impact resistance. For example, HDPE conduits might undergo 1,500 hours of UVA-340 exposure to ensure less than 10% reduction in flexural modulus.
UL 651A: Requires PVC conduits to endure 720 hours of UVA-340 exposure without cracking or significant dimensional change. This standard mandates post-test impact resistance of ≥20 ft-lb (ASTM D2444) for conduits used in high-traffic solar farms.
ISO 105-B02: Assesses colorfastness using xenon-arc lamps, critical for conduits with color-coded safety labels. A ΔE (color difference) value >3.0 after 400 hours may trigger rejection.
5. Conduit Technical Comparison of IEC and AS/NZS Standards
In addition to the requirement for solar conduits to be highly resistant to ultraviolet (UV) light, they must also meet the general performance characteristics expected of electrical conduits.
These include strength, flexibility, impact resistance, and protection against environmental factors such as moisture, chemicals, and temperature variations.
To provide a clearer understanding, this section will briefly compare the performance requirements outlined in the IEC (International Electrotechnical Commission) and AS/NZS (Australian/New Zealand Standards) standards.
This comparison will highlight key differences and similarities in terms of mechanical strength, insulation properties, fire resistance, and weatherproofing, ensuring that solar conduits not only withstand prolonged UV exposure but also perform reliably in diverse installation environments.
For reasons of space, we have selected IEC 61386-21 and IEC 61386-23, AS/NZS 2053.2 and AS/NZS 2053.5, they are specifically addressing flexible and rigid conduit performance.
5.1 Tests in IEC 61386-21 and IEC 61386-23
The IEC standards for rigid and flexible conduits share common test categories such as mechanical, electrical, thermal, fire hazard, external influences, and electromagnetic compatibility . Both include checks for minimum inside diameter after impact and heat tests and reference similar annexes for classification, material thickness, and compliance with IEC 61386-1:2008.
However, the specific test requirements diverge to address material and functional differences. Rigid conduit emphasizes structural integrity, featuring tests for bending strength, collapse resistance, and detailed thread specifications. Flexible conduit, conversely, prioritizes dynamic performance with a dedicated flexing endurance test and omits thread-related requirements.
While both standards addresses force rate calculations, rigid conduit uniquely incorporates collapse testing into this scope. Thus, the overarching categories align, but the tests themselves are tailored to the distinct mechanical behaviors and applications of each conduit type.
5.2 Tests in AS/NZS 2053 Standard
The AS/NZS 2053 Standard outlines test requirements for both flexible and rigid conduits, with shared categories such as mechanical properties, resistance to heat, resistance to burning, electrical characteristics, and external influences. Both conduit types undergo tests for dimensional compliance (Appendix AA for flexible, implied in rigid’s “Dimensions and Form”) and resistance to heat . However, the testing focus diverges significantly based on material behavior.
Flexible conduit emphasizes dynamic performance, featuring specialized tests like the “Test of Ability to Flex” to evaluate repeated bending endurance, alongside a “Test of Ability to Bend” to ensure controlled deformation without damage. Rigid conduit, by contrast, prioritizes structural integrity under static loads, with its “Test of Ability to Bend” likely assessing resistance to permanent deformation rather than flexibility. Additionally, flexible conduit includes unique dimensional measurement protocolstailored to its pliable nature, while rigid conduit omits flexing tests entirely.
Both address heat resistance, but flexible conduit’s test may involve higher thermal cycling to account for material expansion during movement. This distinction ensures each conduit type meets performance criteria aligned with its application—flexible for dynamic environments and rigid for fixed installations.
Both IEC 61386 and AS/NZS 2053 cover similar test categories for rigid and flexible conduits, including mechanical strength, electrical performance, heat resistance, and external influences. Unique tests also reflect these differences. IEC 61386 includes collapse testing for rigid conduits, which is not required for flexible ones, while AS/NZS 2053 adds tailored dimensional measurement for flexible conduits. Additionally, flexible conduit heat tests under AS/NZS 2053 may involve higher thermal cycling to simulate movement. This tailored approach ensures each conduit type meets the demands of its intended application—rigid for strength and flexible for flexibility.
FAQs
1. Do IEC/AS/NZS standards require UV testing for solar conduits?
No, IEC and AS/NZS standards do not specifically require UV testing for solar conduits. However, manufacturers often enhance UV resistance by modifying the material and obtaining third-party certifications, such as UL or CSA, to ensure long-term performance in outdoor conditions.
2. What sets solar conduit apart from regular conduit?
Solar conduit is designed specifically for outdoor use such as solar panel installations. It offers enhanced UV resistance and weather protection to withstand prolonged sun exposure, while traditional conduit may not have the same level of UV and weather resistance.
3. How does solar conduit differ across various standards and regions?
Solar conduit varies across standards and regions in material composition, UV resistance, size, and testing requirements. For example, UL (North America) mandates UV and weather resistance tests. Manufacturers adjust materials, coatings, and sizes to meet local climate and regulatory needs.
