1. Introduction
If youโve ever walked through an electrical supply warehouse in Australia or browsed a conduit supplierโs catalog, youโve likely seen two common terms: HD (Heavy Duty) and MD (Medium Duty) PVC conduits.
At first glance, they might seem similarโboth are made from polyvinyl chloride, both are used to protect cables, and both are certified for use in electrical systems.
๐ค So, what makes one โheavyโ and the other โmediumโ? And more importantly, how do you know which one is right for your job?
Think of HD and MD PVC conduits like different grades of safety boots. Both protect your feet, but one is built for rugged construction sites, while the other is designed for light-duty work. Choosing the wrong one can lead to damage, safety hazards, or failed inspections
This post is written to answer this question, and weโll walk through the main differences between HD PVC Conduits and MD PVC Conduits of Australia standard.
๐ท Whether youโre an engineer, contractor, buyer, or distributor, knowing the difference between HD and MD PVC conduits helps you choose the right product.
โ๏ธ Letโs get started.
2. What Are HD PVC Conduits and MD PVC Conduits?
In Australia, electrical PVC conduits are classified under AS/NZS 2053 standards based on their mechanical performance.
| Compression Class | Compression Force (N) |
|---|---|
| Very Light | 125 N |
| Light | 320 N |
| Medium | 750 N |
| Heavy | 1250 N |
| Very Heavy | 4000 N |
Very Light โ For minimal mechanical stress areas, such as internal walls or ceilings where conduits face little risk of impact.
Light โ Slightly stronger, suitable for indoor use in areas with low physical contact.
๐ Medium โ A balanced choice for general applications with moderate exposure to mechanical forces.
๐ Heavy โ Designed for tough environments, including underground or external sites where impact resistance is crucial.
Very Heavy โ The highest strength rating, used in extreme conditions like heavy industrial zones or locations subject to heavy loads and impacts.
Among these conduit, the two common usage conduit types is Heavy Duty and Medium Duty.
Both types are made from rigid polyvinyl chloride (PVC), valued for its insulation, corrosion resistance, and ease of installation.
However, they are manufactured to different wall thicknesses and performance ratings.
3. Key Differences Between HD PVC Conduits and MD PVC Conduits
3.1 Wall Thickness and Strength
HD conduits are built with thicker walls, which makes them stronger and more impact-resistant.
MD conduits have thinner walls, suitable for environments with less mechanical stress.
๐งฑ This thickness directly affects each typeโs ability to withstand pressure, external force, and environmental wear.
| Nominal Size | HD (Heavy Duty) Wall Thickness | MD (Medium Duty) Wall Thickness |
|---|---|---|
| 16mm | โ | 1.6mm โ 1.9mm |
| 20mm | 2.3mm โ 2.6mm | 1.8mm โ 2.1mm |
| 25mm | 2.5mm โ 2.8mm | 1.8mm โ 2.1mm |
| 32mm | 2.7mm โ 3.0mm | 2.1mm โ 2.4mm |
| 40mm | 3.1mm โ 3.4mm | 2.4mm โ 2.7mm |
| 50mm | 3.4mm โ 3.9mm | 2.8mm โ 3.1mm |
| 63mm | 3.9mm โ 4.5mm | 3.0mm โ 3.5mm |
| 80mm | 4.6mm โ 5.3mm | 3.5mm โ 4.1mm |
| 100mm | 5.9mm โ 6.7mm | 4.5mm โ 5.2mm |
| 125mm | 7.2mm โ 8.1mm | 5.5mm โ 6.3mm |
| 150mm | 8.3mm โ 9.3mm | 6.3mm โ 7.1mm |
๐ก Note: Data above based on Ctube products. Thickness may vary by supplierโalways confirm specifications before use.
3.2 Colour Coding and Identification (Australia Standard)
๐จIn Australia, conduit color is more than just a design choiceโitโs a quick way to identify the duty rating.
๐ According to AS 1345-1995 โ Identification of the Contents of Pipes, Conduits and Ducts, specific colors are used to indicate the contents and application of conduits.
๐ HD Conduits: Typically orange, indicating heavy-duty, suitable for underground or high-impact environments.
๐ MD Conduits: Generally grey, representing medium-duty, often used in wall cavities, ceilings, or light-duty applications.
3.3 Impact and Load Resistance
The AS/NZS 2053 standard has many different tests for conduits. Here, we will use the Test of Resistance to Compression and the Test of Resistance to Impact as examples.
๐ง Compression Test checks how well a conduit resists deformation under steady pressure, simulating conditions like underground burial or heavy loads.
๐ฅ Impact Test measures how the conduit withstands sudden impacts at extreme temperatures (both high and low).
MD conduits handle about 750N force, suitable for medium load environments like normal indoor wiring.
HD conduits are stronger, handling around 1250N, designed for heavy-duty industrial or underground use.
3.4 Environmental Suitability and Application
From the tests we talked about, like the compression and impact tests, itโs easier to understand where these two types of conduits are used.
๐ฆ๏ธ HD conduits are designed to withstand harsh outdoor and underground environments.
Mechanical stress (e.g. from soil pressure or impact during backfilling)
- UV exposure when installed above ground
- Corrosive soil or moisture in underground settings
- Temperature extremes, from high summer heat to winter frost
These characteristics make HD conduits ideal for infrastructure projects, industrial sites, and outdoor cable runs.
๐ In contrast, MD conduits are better suited for indoor installations or areas with minimal physical or environmental stress.
- Running cables within walls, ceilings, or accessible service ducts
- Areas where the conduit is not exposed to UV light
- Situations where lighter weight and easier handling are priorities
While MD conduits can handle standard electrical routing, they are not recommended for underground burial or exposure to harsh weather without additional protection.
๐ ๏ธ Tip: Always assess the installation environmentโtemperature, moisture, exposure, and mechanical riskโbefore selecting your conduit type.
3.5 Cost Differences
๐ฐThe cost of conduits depends on several factors, including the materials used and the weight of the product.
Heavy Duty (HD) conduits usually have thicker walls and stronger materials, which means higher material costs compared to Medium Duty (MD) conduits.
๐ In addition to material costs, the weight of the conduit affects shipping and installation expenses.
๐ฆ For example, a Ctube HD conduit that is 25mm in diameter and 4 meters long weighs about 1.07 kg, while the MD conduit of the same size and length weighs around 0.82 kg.
The heavier HD conduit costs more to transport and can take more time and effort to install, increasing labor costs.
Therefore, when choosing between HD and MD conduits, itโs important to balance the need for strength and durability with the impact on overall project costs, including materials, shipping, and installation.
| Feature | HD PVC Conduits | MD PVC Conduits |
|---|---|---|
| Wall Thickness | Thicker | Thinner |
| Impact & Load Resistance | High โ suitable for harsh conditions | Moderate โ for protected use |
| Common Colour | Orange | Grey |
| Application Areas | Underground, external, industrial | Indoor, light commercial, ceilings |
| Compliance Standard | AS/NZS 2053 | AS/NZS 2053 |
| Cost | Higher | Lower |
๐ฅ Video for you, if youโre interested, check out!
4. Common Features of HD and MD PVC Conduits
So far, weโve focused on the differences between HD and MD PVC conduits. Now, letโs look at what they have in common.
Whether you choose Heavy Duty (HD) or Medium Duty (MD) PVC conduits, both types share many important qualities because of the PVC material and strict Australian standards (AS/NZS 2053).
โก Electrical Properties
PVC conduits are excellent electrical insulators โ they prevent electricity from leaking out and protect people from electric shocks.
Some conduits and fittings also provide electrical continuity when needed, meaning they can safely carry fault currents if designed for it.
Both HD and MD PVC conduits meet these electrical standards to ensure safety and reliability.
๐ง๏ธ Protection Against Water and Dust
PVC conduits are tested to prevent water and dust from entering, which could damage cables or reduce performance.
Proper fittings and correct assembly help achieve the required protection level (IP rating), important for outdoor and underground use.
๐ฅ Flame Retardance
PVC conduits are designed to be flame retardant. So both HD and MD PVC conduits donโt easily catch fire or spread flames, helping contain fire hazards in buildings and underground systems
โ๏ธ Resistance to Environmental Factors๏ธ
Excelleent and standad complying HD and MD PVC conduits are resistant to following situation.
- Corrosion and chemicals โ unlike metal conduits, they wonโt rust or degrade from exposure to soil or moisture.
- Solar radiation (UV light) โ additives in PVC protect it from sunlight damage, making it suitable for outdoor installation.
- Temperature extremes โ PVC can withstand hot and cold conditions without losing strength or flexibility.
๐ Flexibility (for Flexible PVC Conduits)
Flexible PVC conduits pass special bending tests, which means they can curve around corners or fit into tight spaces without damage. This flexibility makes installation easier in complex layouts.
5. How to Choose Between HD and MD PVC Conduits for Your Project
๐ Choosing between HD and MD should depend on:
- Installation environment (underground, wall-mounted, indoor, outdoor)
- Required mechanical protection (load, impact, compression)
- Budget constraints (HD costs more but lasts longer under pressure)
๐ 1. Where You Will Install It
If your conduit will be buried underground, near heavy machinery, or in places with lots of pressure or impact, HD conduit is a better choice. For lighter, indoor use with less stress, MD conduit usually works fine.
๐๏ธ2. How Much Weight or Pressure It Needs to Handle
HD conduits are stronger and can handle higher compression and impact forces. If your project involves heavy loads or harsh environments, HD conduits will last longer and keep cables safer.
๐ฐ 3. Your Budget
MD conduits cost less and are lighter, which can save on transportation and installation costs. But using MD conduits where HD is needed could cause damage and extra repair costs later.
๐ 4. Follow the Rules
Always check local regulations and standards like AS/NZS 2053 to make sure you choose the right conduit type. Using the wrong conduit could break safety rules, cause failures, or even lead to fines.
6. Conclusion
In this post, weโve covered the main differences between Heavy Duty (HD) and Medium Duty (MD) PVC conduits.
The key distinctions lie in their mechanical strength, impact resistance, and suitable environments.
HD conduits are designed for tougher conditions with higher loads and impacts, while MD conduits work well for lighter applications and indoor use.
Choosing the right conduit depends on your projectโs specific needs โ where you install it, how much pressure or impact it must handle, and your budget.
Making a smart choice ensures safety, durability, and compliance with Australian standards.
If you want to know more about heavy duty orange electrical conduit, may be you can read this post Everything You Should Know About Orange Electrical Conduit.
You can also check out this video to learn more.
At Ctube, we offer a wide range of PVC conduits including both flexible conduits and rigid conduits in HD and MD options.
All our products meet the AS/NZS 2053 standards, ensuring excellent flame retardancy, electrical insulation, and strong resistance to compression and impact โ providing peace of mind for your electrical projects.
Thanks for reading! We hope this post helpful. Wishing your project or purchase goes smoothly.
If youโre interested in our products, feel free to contact us for a quote.
