7 tips for choosing corrugated conduit for electrical wiring (cable line)

8 min

The times when the wiring was simply walled up in the wall are long gone. This is very inconvenient, since in which case it will be difficult to access the cable. It is probably not even worth talking about the insecurity of such a decision. The corrugated pipe helps to increase convenience and safety, which protects the cable from mechanical stress, moisture and acts as a dielectric. In some cases, one cannot do without a corrugated pipe, at least this is stated in the rules for the installation of electrical equipment (PUE). There are a lot of different options for its execution, so before buying it is important to figure out how to choose a corrugated pipe for electrical wiring, get acquainted with the assortment and all possible variations.

# 1. What is a corrugated pipe and why is it needed?

A corrugated pipe can be made from different materials, but its structure remains unchanged. It consists of sections with different cross-sections, which regularly alternate with each other. Smaller sections have thinner walls and provide the pipe with excellent flexibility and stretch ability: you can bend the corrugated pipe at almost any angle. Sections of slightly larger diameter are distinguished by increased thickness and play the role of stiffeners, all loads and impacts are assigned to them.

Use of plastic corrugated pipes for electrical wiring allows you to get a number of additional advantages:

  • protection of wires from mechanical damage and negative environmental influences;
  • additional moisture insulation, which is especially important for rooms with a constantly high level of humidity;
  • ensuring fire safety. Self-extinguishing PVC corrugated pipe does not burn and prevents the spread of fire;
  • no need to carry out additional insulation such as shielding and braids;
  • the ability to diagnose and quickly replace the wiring or its part;
  • durability that can be up to 50 years.

# 2. Corrugated tube material

For premises of different types and purposes, with different conditions of temperature and humidity, corrugated pipes from different materials are chosen. At the moment, the most popular solutions are:

  • polyvinyl chloride (PVC), which, thanks to special additives, has the ability to self-extinguish;

  • low pressure polyethylene (HDPE) allows you to get the most flexible pipes;

  • high-pressure polyethylene (LDPE) is used to organize hidden wiring in structures that are not subject to fire (brick, foam block, concrete, etc.). The material can also be used to create the outer layer of double-layer corrugated pipes;

  • polypropylene (PP) is used in rare cases and is indispensable when wiring is equipped during construction using monolithic technology;

  • polyamide (PA) has increased waterproofing, so it will come in handy in rooms with high humidity levels.

The most popular option is PVC; HDPE and LDPE pipes are also often used, their performance characteristics differ slightly. All of them are resistant to moisture, corrosion, do not rot, withstand temperatures from -25 to + 950C.

Note that PVC pipes are the best option in terms of fire safety, but such a corrugation also has a drawback – low resistance to ultraviolet rays, so PVC pipes are best used for organizing hidden electrical wiring or placed inside buildings. HDPE pipes are not so afraid of ultraviolet radiation, therefore they can also be used outside buildings. They are more resistant to cold and heat, but less resistant to fire.

If we are talking about laying electrical wiring in a combustible material (a vivid example is wood), then it is best to use a metal corrugated pipe. It costs more than all plastic counterparts, so it is not used in other cases.

No. 3. Design features of corrugated pipes

Corrugated pipes are divided into:

  • single-layer;
  • two-layer.

With single-layer pipes, everything is clear only from one name. Two-layer assumes the presence of an outer corrugated layer and an inner smooth one. The latter are used less often, but they allow to provide the cable with even higher resistance to mechanical stress.

A probe can be located inside the corrugated pipe. This is a steel wire that runs the length of the pipe. The probe greatly facilitates the process of tightening the wires into the corrugation. On sale you can find a corrugated pipe without a probe. It costs less, but you will have to suffer with the cable tightening into it.

No. 4. Light and heavy corrugated pipes

Depending on the installation conditions and further operation, it may be necessary to use corrugated pipes of different designs, according to which they are divided into the following types:

  • lungs;
  • heavy;
  • superheavy.

Lightweight corrugated pipes are notable for their small thickness, weigh little, bend very well, perfectly take the required shape, therefore, they are as simple as possible in installation. Minus – low resistance to mechanical stress. Such pipes are used mainly for internal wiring, but they can also be used for organizing external wiring, if strong pressure is not applied to the corrugation. Lightweight pipes can be used under plasterboard structures, over stretch and suspended ceilings, and in a car.

Heavy pipes have thicker walls, allowing them to withstand already more severe loads of both mechanical and climatic nature. Such corrugated pipes are used for cement-concrete screed, plaster, for laying highways underground.

There are also super-heavy pipes that are able to provide the maximum level of protection for the wiring. These products are recommended for use in medical and educational institutions where safety comes first.

No. 5. Diameter of corrugated pipes for electrical wiring and their color

The corrugated pipe is produced in coils, the length can be 50-100 m for light corrugations and 2-25 m for heavy ones. Coils are packed in polyethylene shrink wrap for ease of transportation and better preservation of the pipe itself. The outer diameter of the corrugated pipe ranges from 16 to 50 mm, the inner diameter – from 11 to 40 mm, here a lot depends on the type of material used.

The diameter of the corrugation should be selected based on what section the wire is used and how many wires will be simultaneously in the corrugation. Based on vast experience, specialists have formed the following recommendations:

  • a pipe with an outer diameter of 16 mm is suitable for connecting thin cables to sockets, installing computer and telephone networks, alarms and lighting devices;
  • to connect electrical appliances use a corrugation of 20 mm;
  • between junction boxes, the wiring is mounted in a corrugation with a diameter of 25 mm;
  • it is better to use a 32 mm pipe to connect electrical panels;
  • it is better to hide the wiring between floors in a pipe with a diameter of 40-50 mm.

For laying the wiring underground, a double-walled heavy corrugation is used, the diameter of which can reach 200 mm.

If one piece of corrugation was not enough, the connection of different parts is performed using special couplings, split tees, elbows and elbows.

In the production of plastic corrugation, the use of special additives is allowed, which allow the material to be painted in a certain color, but at the same time do not affect its performance in any way. For convenience, you can use a corrugation of a certain color for laying various cables. In order not to get confused, you can focus on a single European standard, according to which:

  • gray corrugation is used for laying general wiring;
  • white – for computer networks;
  • black and brown – for connecting electrical appliances;
  • blue – for a warm floor;
  • red – for external wiring.

Practice dictates that a standard gray corrugation is usually used. Regardless of whether the pipe is painted in some color or not, there should be no foreign inclusions in the material, as well as cracks and chips.

No. 6. Manufacturers of corrugated pipes for electrical wiring

When buying a corrugated pipe, it does not hurt to inquire about the availability of quality certificates. This is not a mere formality, but an important safety requirement. It does not hurt to look at the name of the manufacturer, since large companies will not risk their reputation and produce products of inappropriate quality. Among the largest manufacturers of corrugated pipes, whose products are presented in domestic stores, it is worth noting:

  • LLC “Company” Ekoplast “is a domestic enterprise that manufactures and sells a wide range of materials for electrical wiring, incl. produces a corrugated pipe. The assortment includes PVC, HDPE and PP products, light and heavy pipes, with and without a probe, of various diameters. Production is standardized according to ISO 9001, and the products meet all European requirements;
  • CJSC “RUVINIL” is one of the largest Russian manufacturers of electrical products. Since 1998, the company has mastered the production of a huge type of product, uses modern technologies and high-quality raw materials. The company produces corrugated pipes made of PVC, HDPE and LDPE with a diameter of 16 to 63 mm;
  • MosElektroPlast is another fairly large domestic company that produces a solid list of electrical wiring products. The corrugated pipe is made only of PVC, with a diameter of 16 to 55 mm, there are products with and without a probe, light and heavy;
  • Delta LLC manufactures products under the EnergoPlast trademark. The range includes PVC and HDPE pipes, light and heavy, with and without a probe;
  • “Tyumen Corrugated Pipe Plant” produces PVC pipes of various diameters;
  • NASHORN is a company that is today called one of the largest manufacturers of plastic pipes. For the installation of electrical wiring, they produce a corrugated pipe only from PVC, the range is not very large.

No. 7. Features of working with a corrugated pipe

It is not difficult to lay a cable in a corrugation, at least for those who have at least minimal wiring skills. Connecting and organizing the power grid is already a more complicated issue, so it is better to use the help of professionals if you are not confident in your abilities.

General principles of work in a corrugated pipe:

  • it is better to tighten the cable or bundle of cables into the corrugation together with someone. First, cut off the required length of the pipe fragment. The plastic corrugation can be cut with an ordinary knife, and the probe in it can be cut with nippers or side cutters. After cutting, the steel wire must be held in place, otherwise it may jump inside. The wire is bent. If it is necessary to tighten the bundle of wires, then it is better to pull them off in several places with electrical tape. The resulting harness is attached to the probe using the same electrical tape or thanks to wire wrapping. If one cable is being laid, then it can simply be punctured in the place of insulation. Before starting the pulling, the end of the twist is wrapped with electrical tape. It is easier to wind the cable into the corrugation together;

  • for external wiring, the corrugation is fixed with special clips. When installing in a gutter, special clamps can be used, fastening to quickly solidifying solutions (alabaster) is also allowed;
  • it is necessary to bring the corrugation to switches, sockets and boxes so that the edge of the pipe enters the body, and no bare wires remain outside;
  • there must be at least 10 cm between the corrugation with electrical wiring and the elements of the heating system;
  • if the corrugation is laid in a room with a high level of humidity, the joints must be fitted with seals.

A corrugated pipe is able to make the wiring system in an apartment safer, to reduce the influence of external factors on it, but for this the pipe must be selected and installed correctly.

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Passionate about DIY for over 10 years and all the new tools, I give you through this blog all my advice, tips, tests in all areas: carpentry, electricity, masonry, gardening, home automation ...


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