Topic: precabled conduit, electricity sector

Rigid conduit or flexible corrugated Conduit? which do you use...

The choice of the type of conduit to be used for safe and tidy cable wiring is fundamental: we compare here the rigid conduit and the corrugated flexible conduit, highlighting its characteristics and the most recommended uses for each.


Generally, the conduits used for the plant engineering sector have the purpose of containing the electric cables. The most frequently used conduits are the rigid ones and the flexible corrugated conduits.

Clearly, the different materials and characteristics of the conduit can be explained in the different way of placing them, since the environment in which they are to be installed will influence their durability due to conditions and resistance.
According to the destination, the type of conduit to choose will change.

In general, when working indoors, corrugated may be preferable if the installation is on the wall, on the floor or inside the ground; vice versa, the rigid tube is more compatible if there is a risk of contact with volatile liquids.
If, on the other hand, the laying of cables must be done outdoors, the rigid pipe and the conduit can only be used if they are watertight, where the corrugated material is preferred for work on the ground, on the wall or on the floors.

In the following, we will describe in detail the technical characteristics of the two main types of pipe, illustrating their uses and the methods of installation.


Characteristics and uses of the flexible corrugated conduit

The corrugated conduit, also known as flexible conduit is, as already seen, the most suitable when it comes to laying cables on the wall and on the floor. The reason is not due to the lesser difficulty of installation, but rather to the reduced size of the same: in fact, in order to lay the corrugated conduit it will still be necessary to trace the masonry and the consequent construction works. The positive aspect, however, is given by the better safety of the conduit itself (and better aesthetics too).

The main characteristic of the corrugated is given by its surface which allow greater flexibility, therefore, an ideal use for the laying of cables that must pass under walls and floors where there are also structural obstacles or due to additional non-electric pipes.

On the market there are different classes of diameter of flexible conduits, the choice of which diameter is suitable depends essentially on the thickness of the cables that they will have to contain. From this point of view, it will be necessary to evaluate the ease of passage of the electric cables to be positioned, as well as the possibility of having to insert others in the future; therefore it is good practice not to fill the entire diameter of the tube with electrical cables but to leave empty space for future insertions.

Another element to take into consideration when choosing the diameter of the conduits is the overheating of the cables due to the Joule effect: here too, you need to choose a diameter that allows you to create an air chamber sufficient to dissipate the heat developed.
These are all elements that a good professional installer knows before choosing the diameter of the pipe for the electrical system.

Another precaution to consider when installing corrugated or flexible conduit is their color. There are different colors, which characterize, in compliance with technical regulations, the type of cable that the tube must contain.

In detail:

  • the brown pipes are intended to contain connections for alarms;
  • the blue pipes house the cables for the transmission of audio / video data, such as for example the house telephones;
  • the green pipes are intended for cables that transmit telephone data;
  • the white tubes house the TV data cables;
  • black and gray pipes must be used for the passage of electricity networks;
  • finally, the purple pipes are generally intended for the passage of audio and video signals.



Duct can also be used in the same type of work, even if it is preferred for outdoor installation and as long as the tube is watertight. In addition, the duct can be installed without the need for masonry work, therefore it is much cheaper, but perhaps the aesthetics are affected a bit. The limit in these cases of the conduit lies precisely in the radius of curvature reduced compared to the possibilities of the corrugated pipe, although on the market it can also be found in the form of a spiral sheath to be used in the curves on the track, or in the fittings of the system. It is decidedly more cumbersome and, as seen, it can lead to a non-secondary aesthetic defect (given the fact that it remains visible), unlike the corrugated that does not give rise to these limitations.

Characteristics and uses of the rigid conduit

Unlike corrugated conduit, the rigid conduit is mainly used in outdoor works, since its main feature is the watertight seal which prevents the penetration of rain, liquids and gases.
The same feature, in compliance with safety regulations, requires its use in interiors where there is a danger of contamination of electrical cables with respect to volatile gases or liquids: this can happen, for example, in domestic kitchens or in particular work environments that have this rate of risk.

Another important feature of the rigid conduit is dictated by the fact that its installation is visible, by fixing to the inserts, which are in turn anchored to the wall affected by the installation. Therefore, construction work will not be necessary, making the use of this type of pipes much cheaper.

Nonetheless, as the name suggests, the rigid conduit cannot be used every time curves are needed. Or rather, if its use is chosen in these circumstances, it will be necessary to combine this tube with spiral channels that can act as a fitting to join several rigid tubes to a base.
Furthermore, when setting rigid conduit, rigid curves can be used, which have a fixed angle at 90 degrees (with the obvious and implicit limit represented by the fact that it is not possible to change direction in a different way).
Alternatively, it will be appropriate to use flexible curves of spiral sheath, but here too there is the limit represented by the fact that the fittings are pre-assembled.

It will therefore be necessary to proceed through a preventive study of the possible combinations, so as to find the one that best fits the characteristics of the site.


We have therefore seen how to choose whether to use a flexible corrugated conduit or a rigid tube. It must be taken into consideration both the internal or external place, where the plant will be placed, and the type of materials with which this plant will come or could come into contact. Of course, the intrinsic characteristics of the two types of pipes must also be taken into consideration when the system is technically designed.
In addition to these elements, the installer must also be able to consider the possible future developments that these pipes could support, perhaps envisaging further insertions of cables.
Being able to consider all the elements before designing an electrical system, also envisaging possible implementations, is all within the competence of the installation company.


Posted by Redazione on April 3, 2020

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