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What is Corrugated Conduit?

Jan. 21, 2022

Hi, there, we are coming back.

We’d like to talk about corrugated conduits in this post, and maybe you called them flexible conduits. It's the same thing. But we only talked about non-metallic electrical conduits in this post. If you would like to learn more about different conduit types, you can read our last post here.

The corrugated conduit is a thin wall corrugated tubing that is moisture-resistant and flame retardant. It is pliable such that it can be bent by hand and not threaded due to its corrugated shape. You can see details explained in Wikipedia.

So, the first question is, why the corrugated conduit can be bent by hand but the rigid conduit not?

 


Why Can the Corrugated Conduit be Bend by Hand?

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First of all, most people have not thought about this issue seriously.

We analyze from the physical structure. Under the modern standardized manufacturing process, the corrugated tube produced by the extrusion process of the mold will form a staggered layout within a fixed length of 100%, which means 1/2 part is protruding, and the rest 1/2 part is concave. So the corrugated tube can be bent by hand for sufficient stress space. It can support a specific deformation range to adapt to our different installation environments.

Compared with rigid pipes that must be bent or installed at the corners by conduit fittings, The corrugated conduit can be bent by hand without special tools, which can be very convenient and dramatically saves labor costs.

In short, the design goal of the corrugated conduit is to bend by hand. Then you only need to use simple accessories to adapt to more installation cases. It's just that it has been optimized in terms of structure so that even electrical corrugated tubes made of the same material can be made more flexible.

 

 

What is Corrugated Conduit Used for?

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We generally call Corrugated Conduit in Australia and flexible conduit in North America. However, in this article, we are talking about electrical conduits, so the purpose is generally to protect wires and cables in homes or commercial buildings. And cable management purposes.

But even if it is the same corrugated conduit, it is generally divided into light, medium, and heavy-duty Australia. The main difference between them is the wall thickness, the light type is the thinnest, and the heavy type is the thickest. The thicker the wall thickness of the pipe, the better the firmness and durability. These are similar to the Schedule 40 PVC Electrical Conduit and Schedule 80 PVC Electrical Conduit in North America.

Of course, there is a more straightforward way for the DIY fans to distinguish them by colors. Medium-duty corrugated conduits are generally grey, while heavy-duty corrugated conduits are generally orange. Of course, this is also a common standard for our manufacturers, and it is also following this guide. We always add different toners in the production process to distinguish them.

 


Why is Conduit Corrugated?


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In addition to the parts we have mentioned above, the corrugated conduit can be bent to better adapt to the different projects. It has the following advantages.

 

Wire Protection

Like all corrugated tubes, external forces can effectively damage the wires inside. Especially when exposed to the sun for a long time outdoors or humid underground environment, it can effectively prevent the wires from aging too quickly and protect the safety of electricity.

The flexible electrical conduit can make it show its skills. It can bend easily at the corners of the ground and avoid conflicting areas when installing and constructing underground. For example, where you run the Cat6 Cable, or there are many obstacles or enclosing electrical cable, the corrugated pipe can bypass them more efficiently, and at the same time, provide excellent protection for your cable.

 

Wire Management

When we use wires of different specifications or distinguish the wires of different rooms, we can easily distinguish them using different colors or even different diameters of conduit tubes. Which proved in the installation practice, can save a lot of human resources for research on how wire run. The most important thing is easy to maintain in the next couple of years.

However, you can use a combination strategy of rigid pipes and corrugated pipes to lay out all the wires in a project simultaneously. Adds a set of differentiated signals, which allows you to quickly find the group you need to maintain in a complex circuit.

 

Commercial & Civil House Cases

With the strict environmental protection laws and safety requirements, the use of high-quality wire and conduit can meet these high-demand commercial or civil construction projects. For example, newly constructed hospitals, hotels, laboratories, and other projects have rigorous requirements for decoration materials.

Our newly developed 3rd generation LSZH (Low Smoke Zero Halogen) series of rigid conduit and flexible pipe products have higher impact resistance, chemical corrosion resistance, and high fire rating (UL94 V-0 fire rating). It will automatically extinguish in 5s after cut of the fire sources. Only a tiny of smoke is released and 100% halogen-free, which means improved the survival rate of people in the fire accident. We have already introduced the details, and you can refer to our previous article.

Therefore, we believe that decoration materials will also develop toward green and environmental protection, which is a trend.

 

High Temperature & Chemical Corrosion Resistance

We have already mentioned that high temperature and chemical resistance are natural advantages of PVC corrugated pipes and rigid conduits.

Compared with metal pipes, their chemical stability is better, and special additives can be added during the production process to deal with common chemical attacks.

As for the degree of high-temperature resistance, we list as follows:

PVC Conduit: -25 to 100 (-13 to 212)

LSZH Conduit, -40 to 110 (-40 to 230)

It is the temperature at which both can maintain the regular operation.

 

 

Environmental Protection & Pollution-free

Paying more attention to green and environmental protection is the trend in the future. Materials like PVC plastics have been used for many years, their theoretical service life is more than 100 years, and there are currently more reliable technologies for recycling. So it can be regarded as an environmentally friendly material.

Moreover, with the lightweight and affordable price of plastic pipes, the use cost is also lower. And it can reduce labor costs and shorten the project cycle, so plastic pipes have irreplaceable advantages.

 

 

What Different Between Corrugated Conduits with Rigid Conduits?

As we mentioned before, this is not a simple comparison. Because the design goal of the corrugated conduit is easier to use, it will be bend without any extra special tools to adapt to more installation projects. But each has its Pros and Cons.

 

Corrugated Conduit

Pros,

Easy to install, can adapt to different installation cases

Reduce the fitting used then reduce costs

Cons,

Require special fittings, such as adaptor

Different manufacturers have different formulas and processes, and the bending resistance differs.

 

Rigid Conduit

Pros,

strong and sturdy

A wide variety of accessories can meet the needs of almost all projects.

 

Cons,

It is not easy to bend and requires professional equipment or accessories

Slightly higher installation cost

 

So let's briefly summarize that the two types are complementary, and there is no absolutely better or worse. We need to purchase and use it according to our own needs in actual construction.

 


Can Flexible Conduits be Used Outdoors?

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This question depends on whether the electrical corrugated conduit you buy can resist UV or not & UV rating.

Plastic pipes, especially PVC electrical conduit pipes, have a degree of UV protection. But after adding a unique formula in the production process, the anti-UV ability is greatly improved. And this kind of conduit pipe looks dark gray.

Considering the differences in the formulations of various manufacturers, the anti-UV ability is generally tested in a third party, such as SGS and other institutions. They will follow the process and use professional equipment to simulate the corrugated tube exposed to ultraviolet light in the special UV lighting box, check the aging of the corrugated tube, and finally get detailed data for rating.

If the conduit pipe supplier can provide formal test reports can be used outdoors and resist ultraviolet radiation for a long time.

 

How Deep Should an Electrical Conduit be Buried?

Let us take Australia and the United States as examples.


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The relevant regulations in Australia require that the buried depth of general civil and commercial electrical wires and pipes shall not exceed 500mm, and the buried cables of individual users shall not exceed 300mm when digging their ground. It may be more profound for high voltage, reaching 750mm or even more profound. The relevant regulations of NEC 300.5 in the United States also show that the buried depth of PVC Electrical Conduit shall not exceed 18 inches, or 450mm. The depth can be as deep as 600mm (24 inches) for high-voltage electricity by case.

Is the wire tube buried as deep as possible? The answer is no because maintenance will be more difficult if buried deeper. Moreover, we need to follow national standards, namely NEC (National Electrical Code) related requirements. Otherwise, it may lead to violations of regulations and be punished.

The requirements detail conclusions drawn by different countries after analyzing the qualitative information of each country's location. Another point is that your country may have buried communication cables deep in the ground or built public facilities such as subways. But we don't know, so if the cables are buried too deep, it will cause safety problems.

 

 

Does an Electrical Corrugated Conduit Need to be Glued?

 

We had discussed a similar topic before and concluded that we need to glue the joints of the pipes together, which has two advantages.

First, it can effectively prevent the loosening of the pipe connection caused by external force or other factors to prevent the internal cable from being directly exposed to the air;

Second, glues in the connection of the pipe are filled with smaller glue molecules. The gap at the connection is eliminated, which can make the pipe connection stronger and improve the waterproof performance simultaneously. Avoid underground or ground waters seeping into the pipeline and causing wires damage.

 

What is the Difference Between Corrugated and Split Corrugated Pipe?


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They are both corrugated conduits, and the process flow is not much different. The only difference is that during the production process of the created split, a section will not be completely closed when the mold has been designed, thus forming the shape of the opening. So their functions are almost the same.

Of course, although they seem to be only slightly different in appearance, there are advantages to this design. It is easier for us to run the wires.

No additional tools and tie the thread and press it directly. This slight improvement greatly improved construction performance and subsequent maintenance.

However, the disadvantages are also evident. There is no fully enclosed corrugated tube, the impact resistance has been down, and there is a greater chance that the wire will be directly exposed to the air, especially after the conduit pipe is aged or damaged.

However, we believe that it is very convenient if used in mechanical equipment or facilities for it often needs maintenance. The corrugated conduit needs to be checked usually when damaged or aging. In this case, it is beneficial.

 

That's it, and I hope you are clear after reading this post. If you have other questions or want to learn about our products, you can contact us by submitting the contact form or the floating toolbar on the right. Thanks again for reading.

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