1. Introduction
Electrical conduits play a vital role in protecting electrical wiring from physical damage and environmental factors. Conduits not only safeguard cables from impact, abrasion, and moisture but also help prevent potential hazards like electrical fires. PVC (Polyvinyl Chloride) conduits are particularly favored in electrical installations due to their strength, resistance to corrosion, and ease of installation. PVC conduits come in various forms, including rigid and corrugated types, each designed to address specific installation needs.
Rigid PVC conduit is the most common choice for protecting cables in permanent, high-impact environments such as underground installations or exposed industrial settings. PVC corrugated conduit, on the other hand, is more flexible, offering an adaptable solution for applications where the conduit needs to bend and twist around obstacles.
In Australia and New Zealand, electrical conduit installations are governed by strict standards to ensure safety, performance, and reliability. The AS/NZS 2053 series of standards dictate the requirements for the use, installation, and performance of electrical conduits.
AS/NZS 2053.1:2001 is a general requirements for Conduits and fittings electrical installations.
AS/NZS 2053.2:2001 deals with rigid conduit installation and the conditions under which it can be used.
AS/NZS 2053.5:2001 focuses on the characteristics and installation of flexible and corrugated conduits, outlining their usage in various installations.
This post explores the main differences between Australian Standard PVC Rigid Conduit and PVC Corrugated Conduit, using these standards as the foundation for comparison.
2. General and Common Requirements of PVC Rigid & Corrugated Conduit (AS/NZS 2053.1:2001)
PVC rigid and corrugated conduits differ in appearance and certain applications, but they share several performance requirements. After briefly outlining their common features, we will delve into the specific differences between the two.
2.1 Construction
The construction of PVC conduits and fittings must ensure durability and safety by adhering to specific quality standards. Surfaces, both inside and outside, should be free from burrs, flashes, and defects that could damage cables, with slight manufacturing burrs allowed if they pose no risk. Conduit ends must be square within 2ยฐ, free of chips or rough edges, to prevent cable damage. For proper connectivity, each conduit length must include a socket, coupling, or suitable connection facility that complies with dimensional standards.
Additionally, the concentricity of sockets and fittings is critical, requiring the inside diameter to align with the outside diameter within 2.5% of the nominal size, and the socket axis to remain parallel to the conduit axis within +2ยฐ. These requirements ensure smooth cable installation, structural integrity, and compliance with AS/NZS standards.
2.2 Mechanical Properties
Conduits and fittings must exhibit sufficient mechanical strength to withstand bending, compression, shocks, and extreme temperatures without significant deformation that could hinder cable installation or cause damage during cable insertion. Their mechanical integrity must remain intact both during and after installation.
Compliance is verified through various tests based on classification and conduit type, including bending (Clause 9.2), compression (Clause 9.3), impact (Clause 9.4 for non-oval conduits), collapse (Clause 9.5), and pull-out strength of joints (Clause 9.6 for non-threadable conduits). These tests, detailed in corresponding appendices, ensure the durability and performance of conduits and fittings in accordance with AS/NZS standards.
2.3 Compression Test
According to general requirements, conduit can classified into 5 duty types withstand different compression force.
| Conduits | Compression Force (N) |
| Very Light | 125 |
| Light | 320 |
| Medium | 750 |
| Heavy | 1250 |
| Very Heavy | 4000 |
2.4 Resistance to Heat
The heat resistance test evaluates the ability of conduits and fittings to withstand high temperatures without significant deformation.
Equipment and Test Pieces: The test uses a ball-pressure apparatus and a heating chamber capable of maintaining the manufacturerโs specified maximum service temperature (ยฑ5ยฐC). Test pieces include three sections of conduit (cut into 80 mm halves) or three pieces from separate fittings.
Procedure: The test involves heating the ball-pressure apparatus and steel support to the specified temperature. The test piece is then placed in the heating chamber, where a 5 mm steel ball is pressed against its surface with a force of 20 N for 60 minutes. After heating, the piece is rapidly cooled in water to room temperature, and the diameter of the impression left by the ball is measured.
Acceptance Criteria: The test is passed if the diameter of the ballโs impression on the test piece does not exceed 2 mm, ensuring the material retains its structural integrity under high-temperature conditions.
2.5 Resistance To Burning
A sample is considered to have passed the test if it meets all of the following conditions. By meeting these criteria, the sample demonstrates sufficient resistance to flame propagation.
- No Ignition: The sample does not ignite when exposed to the test flame.
- Limited Burn Area: After burning ceases, there is no evidence of burning or charring within:
50 mm of the lower extremity of the upper clamp.
50 mm of the upper extremity of the lower clamp. - Self-Extinguishing: If the sample ignites, combustion must stop within 30 seconds after the flame is removed.
- No Tissue Ignition: The tissue paper beneath the sample does not ignite during the test.
- Molten Material: Any molten material present on the sample does not cause burning or charring.
2.7 External Influences
2.7.1 Ingress of Water and Protection Against Moisture
If required, conduits and fittings must be classified and tested for their level of protection against water ingress, in accordance with AS 1939. The system (conduit + fitting) is assembled according to the manufacturerโs instructions before being tested. The method of assembly and the types of fittings used will affect the IP (Ingress Protection) rating. The IP rating defines how well the product is protected against dust and water, such as whether itโs waterproof or resistant to jets of water.
Conduits classified as non-hygroscopic must pass moisture absorption tests. The test involves immersing a sample in water and ensuring moisture absorption does not exceed 5% of its dry mass.
Conduits and fittings of insulating material are classified as having high protection outside and inside against corrosive and polluting substances and need not be tested.
2.7.2 Ingress of Solid Foreign Objects
Similar to the ingress of water, the conduit system must be classified and tested for its protection against solid foreign objects, according to AS 1939. The test setup and assembly of the conduit system (including the types of fittings used) will impact the resulting IP rating, ensuring that no solid objects can enter the conduit system in specific conditions (e.g., dust, dirt, etc.).
2.7.3 Solar Radiation
Currently, no practical test for protection against solar radiation is included in the standard. However, based on experience, the following additives are recommended for providing solar radiation protection.
UPVC (Unplasticized PVC): Add 1.5% of titanium dioxide (TiO2) resin to enhance solar radiation resistance. Plasticized PVC and Polyethylene: Add 2% carbon black to improve solar radiation resistance.
2.8 Acid-Gas Emission
For conduits and fittings classified as halogen-free, the acid-gas emission test must meet the following requirement. When tested according to AS 1660.5.3, the material should emit no more than 5 mg of hydrochloric acid per gram of the sample.
2.9 Electromagnetic Compatability
Products covered by this standard are typically passive in terms of electromagnetic influence (both emission and immunity). This means that under normal conditions, the conduits and fittings do not emit electromagnetic interference (EMI), nor are they sensitive to it.
2.10 Electrical Characteristics
Electrical continuity is not applicable for PVC rigid and corrugated conduit. While PVC rigid and corrugated conduit shall pass the test of insulating strength of conduits.
Appendix G of the AS/NZS 2053.1:2001 standard outlines the testing procedure for evaluating the electrical insulating strength of conduits. The test involves immersing a test piece of conduit in a saltwater solution and applying a gradually increasing AC voltage, ranging from 1000 V to 2000 V, to assess the conduitโs ability to withstand electrical stress without failing. After maintaining the voltage for a specified time, the insulation resistance is measured to ensure it meets the minimum requirement of 100 Mฮฉ. The test is designed to ensure that conduits can safely handle electrical currents and provide adequate insulation under normal operating conditions, without allowing excessive leakage or breakdown.
3. PVC Rigid Plain Conduit (AS/NZS 2053.2:2001) VS PVC Corrugated Conduit (AS/NZS 2053.5:2001)
3.1 Definition
AS/NZS 2053.2:2001, this Standard specifies requirements for rigid, plain, non-threadable conduits and fittings made of insulating material used to protect cables in electrical installations. This Standard shall be read in conjunction with AS/NZS 2053.1.
According to AS/NZS 2053.1: 2001 General Requirements. Plain conduits is that conduits having profiles which are even in the longitudinal section. Rigid conduit is that conduits which are normally bent with the help of a mechanical aid and with or without special treatment.
While pliable conduits which can be bent by hand using a reasonable force but without other assistance. Pliable conduits which deform when transverse forces are applied for a short time and which, after removal of the force, return to their original shape after a further short time. So called flexible conduit and corrugated conduit.
3.2 Conduit Sizes
3.2.1 Diameter and Wall Thickness
According to AS/NZS 2053.2:2001, the diameter and wall thickness of the rigid conduit shall be measured in accordance with AS/NZS 1462.1 and shall comply with the dimensions given in Table 101.
AS/NZS 1462.1 specifies the methods for testing the dimensions of plastic pipes and fittings, including measurements such as outside diameter, wall thickness, length, and squareness of pipe ends. This standard is crucial for ensuring that these components meet the necessary specifications for safe and effective use in various applications, particularly in plumbing and water management systems. This standard mentioned details about the test ambient temperature, testing procedures and tools and more.
The wall thickness of very heavy duty conduits shall not be less than that of the same nominal size of heavy duty conduits.
At the same, flexible conduits and fittings shall be designated in terms of the nominal sizes listed in Table 101. The nominal sizes are based on the relevant outside diameters of conduits.
The inside and outside diameters of flexible conduits and the bores of fittings shall comply with Table 101. Conduits that have a smooth bore and a corrugated outside profile need not comply with Table 101 for outside diameters.
3.2.2 Length of Conduit
Unless otherwise specified by the supplier or purchaser, conduit shall be supplied in the following standard effective lengths, exclusive of coupling.
The effective length of socketed conduits shall be the overall length, less the insertion depth. (Length shall be measured in accordance with AS/NZS 1462.1)
| Size of Conduit | Length |
| Up to and including size 63 | 4m + 20, -0 m |
| Above size 63 | 6m + 50, -0 m |
3.2.3 Conduit Ends
Couplings or sockets supplied on conduit ends shall conform to the dimensions given in Table 102 and shall be measured as indicated in Figure 101. The dimensions of sockets and couplings shall be determined in accordance with AS/NZS 1462.1.
3.3 Bending test
Conduits are classified based on their mechanical stress tolerance and diameter, which determines their need to undergo a bending test.
Conduits with Diameters Less Than 32 mm. These conduits must pass the bending test outlined in Appendix AA, depending on their classification:
- Very Light Mechanical Stress: Suitable for minimal mechanical loads, such as small-scale residential installations.
- Light Mechanical Stress: Designed for moderate mechanical loads, often found in light commercial applications.
- Medium Mechanical Stress: Capable of handling more robust mechanical demands, suitable for industrial or heavy-duty use.
3.4 Compression Test
Rigid Conduits shall pass the test of resistance to compression in Part 1. The difference between the initial outside diameter and the diameter measured with the force applied shall not exceed 10%.
Flexible Conduits shall pass the test of resistance to compression in Part 1 except that the difference measured between the initial outside diameter and the diameter measured with the force still applied shall not exceed 25%.
Conduits with Diameters Equal to or Greater Than 32 mm. Larger-diameter conduits, as well as those classified as heavy-duty or very heavy-duty, are exempt from the bending test. These conduits are inherently more rigid and capable of withstanding significant mechanical stress without deformation, making additional bending tests unnecessary.
The bending test ensures that conduits can endure mechanical stress during installation while maintaining their structural integrity. The process involves using a bending device and a coiled spring or bending aid to simulate a 90ยฐ bend on a 500 mm conduit section. The test piece is clamped in place, bent using rollers through a 180ยฐ motion, and then released to form a 90ยฐ bend.
To pass the test, the conduit must show no visible cracks when inspected with normal or corrected vision. This test confirms the durability and flexibility of the conduit, ensuring it can be installed without damage or deformation that could hinder its performance.
3.5 Collapse Test
Conduits with diameters under 32 mm, classified for very light, light, or medium mechanical stress, must pass a collapse resistance test outlined in Part 1.
About rigid conduit, the test involves using a bending device (as shown in Figure 102). After heating, the conduitโs internal diameter is verified by attempting to pass a specific gauge (Figure 103) through it, with the conduit positioned at a 45ยฐ angle.
However, conduits with diameters of 32 mm or larger, as well as heavy-duty and very heavy-duty types, are exempt from this collapse test. This ensures that smaller conduits meet the necessary durability standards without requiring unnecessary testing for larger, more robust conduits.
Flexible Conduits shall pass the test of resistance to collapse in Part 1. The bending device used shall be that shown in Figure BB 1 in this Part.
3.6 Detailed Comparison: Applications of Rigid Conduit vs. Flexible Conduit
Rigid conduits are designed for environments where maximum protection and durability are paramount. Their applications emphasize structural stability and resistance to external stresses.
Industrial and Outdoor Environments: Rigid conduits are highly suitable for industrial plants, warehouses, and outdoor installations where environmental factors like rain, UV rays, and mechanical impacts are prevalent. For instance, PVC rigid conduits resist corrosion, making them an excellent choice for humid or chemical-exposed areas.
Underground Installations: The strength of rigid conduits allows them to withstand soil pressure, making them ideal for underground electrical wiring. Rigid conduits protect cables from moisture, rodents, and potential damage caused by digging or heavy loads.
Straight and Structured Installations: In settings where long, straight conduit runs are required, such as in commercial buildings or large-scale infrastructure projects, rigid conduits maintain a professional and secure installation. They work well in designs where bending is minimal and consistent alignment is critical.
High-Impact Areas: Rigid conduits are used in environments where they may be exposed to heavy machinery, falling objects, or vehicle traffic, such as in factories, workshops, or parking garages. Their robust construction ensures electrical wires remain well-protected.
Flexible conduits are specifically designed to address situations where adaptability and ease of installation are essential. Their applications highlight versatility and dynamic performance:
Tight Spaces and Complex Pathways: Flexible conduits are the preferred choice for areas where conduits need to navigate around obstacles or through tight spaces, such as within walls, ceilings, or machinery. Their ability to bend without additional fittings makes them a practical option for confined installations.
Dynamic and Vibrating Equipment: In applications where equipment is constantly moving or subject to vibrations, such as in robotics, conveyor systems, or HVAC units, flexible conduits excel. They allow movement while maintaining protection for the wires inside.
Temporary or Quick Installations: For temporary wiring setups, such as construction sites or event installations, flexible conduits are lightweight and quick to install. Their ease of handling reduces installation time compared to rigid conduits, making them a convenient choice for short-term projects.
Indoor and Low-Stress Applications: Flexible conduits are commonly used in residential and light commercial environments. Examples include connecting appliances, lighting systems, or other low-voltage applications where extreme durability isnโt a primary concern but ease of adjustment is beneficial.
4. Key Features of Ctubeโs AS/NZS 2053 Standard
Ctube takes pride in offering PVC rigid conduit and flexible conduits that meet the stringent requirements of the AS/NZS 2053 standard, ensuring top-notch quality and performance for electrical installations. These conduits are meticulously engineered to align with the standard specifications for size, length, and thickness, guaranteeing consistency and reliability.
Wide Temperature Resistance: With a performance range of -15ยฐC to 105ยฐC, these conduits are designed to endure both extreme cold and high-temperature environments, making them suitable for diverse applications in residential, commercial, and industrial settings.
Flame Retardant Properties: Safety is a priority. Ctubeโs conduits are flame retardant, reducing the risk of fire spread and ensuring a secure conduit system for electrical wiring.
Dimensional Accuracy: Manufactured with precision, our conduits adhere to the specified size, length, and thickness requirements outlined in the AS/NZS 2053 standard. This ensures compatibility with various fittings and seamless integration into conduit systems.
Durability and Longevity: Crafted from high-quality PVC and UPVC materials, the conduits offer exceptional resistance to impact, corrosion, and UV exposure. This robustness contributes to their extended lifespan, even in challenging environmental conditions.
Ctube also provides customization to meet specific project requirements, including: Different sizes and lengths for varying installation needs. Colored conduits for easy identification and organization of wiring systems. If you have projects requirements, please contact us.
FAQs
1. Can rigid conduits be used in curved or irregular pathways?
Rigid conduits are less suitable for curved or irregular pathways because they require additional fittings and precise bending tools to create turns. Flexible conduits are a more efficient choice for such situations.
2. Are the colors of conduits standardized?
While there are general industry practices, conduit colors are not universally standardized. They may vary by manufacturer, region, or specific project requirements. Itโs essential to refer to local codes and standards or the manufacturerโs guidelines when selecting conduit colors.
In Australia and New Zealand, certain color customs and recommendations are followed:
- Gray: Preferred for medium-duty conduits systems.
- Orange: Used for heavy-duty electrical systems. And for underground application.
- White: Designated for communication or data cabling.
3. Are rigid conduits better for underground wiring?
Yes, rigid conduits are the preferred choice for underground wiring as they provide excellent resistance to soil pressure, moisture, and other potential damages, ensuring long-term protection for electrical cables. Some can be buried in direct burials, some need to be encased in concrete. However, flexible conduits is not recommend to use for underground without concreted.
