Metal pipe for electrical wiring: characteristics and rules for installing wires

The use of plastic pipes for electrical wiring

HDPE pipes for electrical wiring are considered a new generation of materials that have a number of undeniable advantages compared to metal pipes.
HDPE pipes for cable have the following advantages:

high resistance to corrosion and chemicals;
long service life (up to 50 years);
low weight, making such pipes easy to transport and lay;
there is no need for additional wire protection;
moisture that gets inside the pipe will not begin to destroy it from the inside;
small cross-section pipes bend easily;
relatively low cost of material;
you can assemble a ready-made system without having any special knowledge or skills for this type of work.

Smooth PVC electrical pipes are made by continuous extrusion and are characterized by low linear expansion, rigidity and stability. Such pipes are ideal for laying electrical wiring in concrete structures. There are PVC pipes with sections of 16-50 mm, although their length does not exceed 3 meters.

Smooth pipes are designed to protect the cable from mechanical damage. They can be laid as open wiring on the ceiling made of low- and non-flammable materials. There are many types of PVC pipes: rigid, smooth, reinforced and corrugated. And they all differ in their own characteristics, which will be relevant in each individual case. For example, pipes with smooth walls are used for laying and protecting wires in the walls of residential buildings, as well as administrative and industrial structures. Their main goal is to obtain an extremely reliable electrical wiring system.

Smooth single-wall HDPE pipes are suitable for pouring concrete, as well as for laying them in brick walls. They are connected using special tees, couplings, bends, and so on.

Positive qualities of such pipes:

service life of at least 50 years;
are not afraid of low temperatures;
the cross-section of the pipes does not change during the entire service life, no deposits accumulate on the internal walls, and moisture does not collect on the external walls;
excellent smooth pipe surface that does not need to be treated or covered with paint;
do not pose a danger to the environment, plus they are very easy and safe to work with;
light weight and reasonable price.

Manufacturers and prices: is there a difference?

Here you must immediately understand that the main component of the cost is the amount of material spent on manufacturing. Plus transportation costs. The higher the quality of the plastic, and the more of it in the finished structure (the thicker and stronger the walls), the higher the price. Just like with cable, where the main pricing factor is the quantity and quality of copper.

And exactly the opposite: the lowest price will be for cheap plastic of dubious performance characteristics, which is also slightly under-produced.

Don't buy the cheapest noname!

As Evgeniy explained, the game of saving is not worth the candle. The difference in price between low-quality products from unknown manufacturers, with which the markets are flooded (especially a lot of penny corrugation), and factory-certified goods is insignificant.

So, you can buy a coil of normal pipe for installing internal electrical wiring for about 200 UAH. (focus on brands no less than the level of Kopos, DKC, IEK). And for something you don’t understand, you’ll pay 170-175 UAH at the market.

On volumes for the entire apartment, you will save 25 hryvnia - in absolute terms, a penny benefit is not worth the risks.

What exactly are the risks that come with a low price tag?

Firstly, no-name products without certificates and documents confirming their origin more than likely have defects that contradict the standards. Damage, ruptures, sagging, swelling, and delamination of the material are possible. As a result, a low degree of wear resistance and a high degree of fragility. The big question is the amount of plastic itself - perhaps they saved money on the thickness of the walls, and whether such corrugation is able to fulfill its function is unknown.

Related articles: Wires and cables for special purposes

Secondly, the quality of the plastic is unknown. How flammable/non-flammable is it really? I wouldn't want to test this in an extreme situation. What about toxicity? The nameless manufacturer does not provide information about the composition of cheap, non-certified material produced in artisanal conditions. How to make sure that its formula does not contain dangerous plasticizers - phthalates, or lead, formaldehyde, cadmium? And you and your loved ones will live and breathe here for decades.

Therefore, when making electrical installations in a house and laying cables in pipes, it is much more reasonable to lay them in pipes made of durable, non-flammable PVC that does not pose a risk of toxic fumes, which is confirmed by documents. And do this according to certain rules.

The difference between cables and wires depending on the core material

Cores of wires and cables for specialized purposes can be made of various metals, but aluminum and copper are mainly used in electrical engineering. Each of them has its own specific properties, advantages and disadvantages, which must be taken into account when selecting a core material for a specific purpose.

Aluminum conductors

The invention of a relatively inexpensive method for extracting aluminum made a revolution in the global development of electrification, because in terms of electrical conductivity this metal ranks fourth, behind only silver, copper and gold. This made it possible to reduce the cost of production of wires and cables as much as possible and make universal electrification a reality.

Such electrical wires and their types are distinguished by their low cost, chemical resistance, high level of heat transfer and low weight - they have determined the mass of electrification in industrial and domestic conditions for more than half a century.

In light of the relatively recent dominance of aluminum in the wire market, it may seem strange to the uninitiated that the provisions of the PUE prohibit the use of this material in everyday life. More precisely, you cannot use aluminum wires with a cross-section of less than 16 mm², and these are the most common of them for installing home electrical wiring. To understand why there is a ban on the use of these wires, you can familiarize yourself with their advantages and disadvantages.

+ Advantages of aluminum wires

Lighter than copper.
Significantly cheaper.

— Disadvantages of aluminum wires

Aluminum conductors with a cross-section of up to 16 mm² can only be single-wire, which means they can only be used for laying stationary wiring and without bending at an acute angle. All flexible wires and cables have always been made of copper.
The chemical resistance of aluminum is determined by the oxide film that forms when it comes into contact with air. Over time, with constant heating of the contact due to the flow of electric current through it, this film deteriorates electrical conductivity, the contact overheats and fails. That is, aluminum wires require additional maintenance, and the contacts through which powerful currents pass are coated with a special lubricant.
Amorphous material - if you clamp two aluminum wires together, the contact will weaken over time, as the aluminum will partially “leak out” from under pressure.
Soldering can only be carried out using special tools, and welding can be performed in a chamber with an inert gas.
Good electrical conductivity is observed only in pure aluminum, and impurities inevitably remaining during production worsen this indicator.

As a result, aluminum is a good choice if you need to save money here and now, but in the long run its use will be more expensive due to its relatively short service life and the need for regular maintenance. For this reason and additional safety reasons, the PUE strictly prohibits using it for laying new power lines.

Copper conductors

In terms of electrical conductivity, copper is in second place, only 5% inferior to silver in this indicator.

Compared to aluminum, copper has only 2 significant disadvantages, due to which for a long time it was used much less frequently. Otherwise, copper wins in all respects.

+ Pros of copper wires

Electrical conductivity is 1.7 times higher than aluminum - a smaller cross-section of wire will pass the same amount of current.
High flexibility and elasticity - even single-core wires can withstand a large number of deformations, and multi-core wires make cords for electrical appliances with increased flexibility.
Soldering, tinning and welding are carried out without the use of additional materials.

— Disadvantages of copper wires

The cost is several times more expensive than aluminum.
High density - a coil of copper wire, the same length and cross-section as aluminum, will weigh 3 times more.
Copper wires and contacts oxidize in open air. However, this practically does not affect the contact resistance and, if necessary, is “treated” by lubricating the surface of the already tightened contact.

As a result, although copper is a more expensive material, in general its use is more economical, since it is more durable, requires less effort during installation and attention during maintenance.

Types of pipes for electrical wiring

Now it's time to choose steel pipes for electrical wiring. They differ in the material of manufacture, wall thickness and some other parameters. In addition, we will focus on plastic pipes, which can also be irreplaceable in some cases.

Plastic pipes

Plastic pipes are used to protect electrical wiring in damp areas and for outdoor installations. They differ quite greatly in the material of manufacture and their basic properties, but for the most part they provide fairly good mechanical protection for the wires.

Plastic pipes for electrical wiring

At the moment, polypropylene pipes are produced. They can be smooth-walled or corrugated. Quite often, polypropylene pipes are reinforced with aluminum or copper, which increases their stability and reliability.
PVC pipes have good mechanical characteristics, but they are not as flexible. Therefore, their use in electrical engineering is somewhat limited.
Pipes made of high and low pressure polyethylene are characterized by high flexibility and excellent mechanical properties. And while products made from low-density polyethylene are practically never used, their analogues made from high-density polyethylene have found wide application in electrical engineering.
The advantages of plastic pipes include the ease of installation with your own hands. They are light in weight and have fairly good mechanical characteristics. Such pipes are not exposed to chemically active substances and corrosion, and have good dielectric properties.
At the same time, the instructions for their use have serious limitations, which are primarily related to the flammability of this material. Therefore, the use of plastic pipes for installation on combustible surfaces has a number of limitations. In addition, the disadvantages include the insufficient protection of such pipes from rodents.

Metal pipes

Metal pipe for electrical wiring is used for mechanical protection of the wire. It differs in such properties as: material of manufacture, pipe diameter and wall thickness. Thin-walled pipes are those with a wall thickness of 1.6 to 2.5 mm. Conventional pipes have a wall thickness of more than 2.5 mm.

Metal pipes in electrical engineering

There are water and gas pipes with a diameter of 4 to 10 mm, water pipes with a diameter of 10 to 50 mm, and electric welding pipes with a diameter of 15 to 50 mm. All of them can have different wall thicknesses, based on which their application and installation method are determined.
A steel pipe for electrical wiring with a thick wall is usually installed by welding. Such pipes are distinguished by their relatively low cost, almost complete immunity to temperature changes and high strength. At the same time, the cost of installing such pipes is quite high, they require additional processing in the form of painting, and their service life is not very long.
Metal pipes for electrical wiring with a thin wall are fastened using threads or special fasteners. Their main advantages include low cost and installation costs. At the same time, in terms of parameters such as durability, strength and application capabilities, they are in many ways inferior to their counterparts with thicker walls.
If you are looking for more durable pipes, then you can pay attention to galvanized pipes. The durability of such products significantly exceeds the durability of steel pipes, but this condition is met only with proper installation. Another significant disadvantage is the price of such products.

Note! When welding galvanized pipes in the usual way, the zinc coating layer is destroyed. As a result, they require either additional processing at the joints, or flux should be used during installation. It is also worth remembering that during welding work with such pipes toxic compounds are released.

Stainless steel pipes are also available on the market. Such products, of course, have a very long service life, but given their cost and complexity of installation, the rationality of their use as protection for electrical wiring is questionable.
Copper pipes for electrical wiring are a separate element. This version of pipes appeared relatively recently and has not yet proven itself. But in many cases it can be optimal. Indeed, given the relative ease of installation, aesthetics and durability of such pipes, in many cases they can be an ideal option.

Application of copper pipes

Copper pipes for electrical wiring are quite flexible, resistant to many chemically active substances and are not subject to corrosion. The main obstacle to their widespread use is their cost and poor wear resistance.
I would also like to note profile pipes, which have recently found increasing use. Their main difference is their shape, which differs from the generally accepted round one. In some cases this may be the deciding factor. They can be thin-walled or thick-walled and otherwise practically do not differ from other types of pipes.

Selection of metal pipes for cable laying

The electric cable can be laid in almost any pipes.

Why is the cable placed in a metal pipe?

During operation, electrical wiring is subject to various influences. From the inside, these are voltage surges that can lead to destruction of the wire and braid. From the outside, the strength of the electrical cable can be threatened by humidity, ultraviolet radiation, and chemically aggressive substances. But the most common cause of cable damage is physical impact: impact, compression, stretching. Even wiring hidden in a wall, floor, ceiling or underground can be damaged by a drill or chisel during repairs, elements of supporting structures during shrinkage, or soil compression when moving equipment over buried communication lines.

In most cases, a polymer box or corrugated steel casing will provide sufficient protection for power cables.

But there are situations when you have to resort to a more expensive and technically complex solution - laying electrical cables in a metal pipeline:

If the room in which the electrical network section is located is built from flammable materials, or such materials are used in decoration and furnishings. In a wooden house, in a bathhouse or on a terrace, wooden walls or cladding can easily catch fire even from a small spark if the cable’s braid is damaged.

Note! Building codes do not provide for laying electrical wiring in metal pipes in such premises, but only this method of protecting electrical cables can ensure fire safety.

If the room itself is a fire hazard due to its functional purpose. For example, in a workshop where they work with metal, a spark from a welding machine or grinder can burn through the braid of an electrical wire and cause a short circuit. In the kitchen or boiler room, the wiring of an oven, stove, or heating boiler is dangerous. In such rooms, not all electrical wiring can be hidden in metal pipes, but only areas located in fire hazardous areas.
The use of pipes when laying electrical cables underground is necessary, especially in rocky soil, under roads and footpaths. In such areas, the wire is threatened by the movement of stones during soil shrinkage, soil pressure and rodents living underground.
If the electrical wiring is laid openly, where there is a high risk of mechanical damage. For example, in a gym where they work with exercise equipment, it is easy to pinch or break the cable; in a workshop where glass, wood or stone is processed, a splinter of the material being processed can damage the braid.
If metal pipes are a decorative element. The loft style, in which they try to give the room a resemblance to an industrial facility, involves laying communications in an open way. Vintage or retro style also involves laying wiring along the walls and ceiling - metal for insulation in this case is more suitable than other materials both in style and in safety.

We recommend that you familiarize yourself with: Main manufacturing plants of profile pipes in the Russian Federation

Why water pipes are not suitable for cable

You may have repeatedly seen how cable laying (for example, to the distribution panel of a private cottage) is carried out in the ground using pipes for process water. So, this is far from the best solution.

Polyethylene pipes for process water are not advisable from the point of view of safety and economy

The truth is that water pipes, if they are without water, burn very quickly (when they are used as expected, with water, then, of course, they do not burn). Immediately a solid argument “against”. In principle, it is possible to lay cables in water pipes, but only if the entire structure is buried underground. In this case, there is no oxygen, which means there is no danger of combustion.

What about mechanical protection? There is also a big question here. Electrical cable pipes are designed to withstand external pressure in the form of compression. But water pipes maintain the pressure of water from the inside, so they are made to be resistant to pressure - this is a completely different specificity and, accordingly, design.

It should also be noted that this method is economically inappropriate. The fact is that the cost of pressure water pipes is higher than electrical installation ones.

In general, water pipes are not used for wiring because:

they are more expensive
they are flammable.

But if you have an extra ten meters of water supply, you can bury it with a cable to the nearest outbuilding on your summer cottage. But the electrical installation is still an order of magnitude better for laying in the ground, because it is strengthened precisely from the process of squeezing from the outside.

Don't need such a dubious compromise? Then you will have to choose from the originally intended options to lay the cable in the pipes.

Cable AKVVGng

AKVVGng cable The AKVVGng cable is used for connection to various control systems, as well as electrical appliances.
Experts recommend purchasing it when a fixed gasket is needed. The product can be placed both outdoors and in the ground. It is also laid in special structures: channels, tunnels, boxes. Order

Electrical wiring is:

• open – under ceilings, along walls, supports, trusses and other building elements of buildings;
• hidden - inside structural elements (in walls, foundations, ceilings, under the floor) with or without the use of plaster, with or without the use of pipes, boxes;
• external (can be open or hidden) – along external walls, under awnings (street).

If there is a high groundwater level in the territory of open distribution installations (abbreviation ORU), then cable lines are laid above ground (according to clause 2.3.111). When laying on reinforced concrete trays or slabs, a slope of 0.2% is provided for drainage of storm water or openings are made in the bottom.

Features of the use of pipes made of PVC, HDPE and steel

Polyvinyl chloride (PVC) - frost resistance down to -15 ° C, loss of strength when exposed to solar radiation, that is, when laid outdoors (street), it will crumble after winter (only for indoors and buildings).

Made from low-density polyethylene (HDPE or HDPE) – frost resistance down to -45 °C, resistance to chemicals and solvents, dielectric (resistance of at least 100 MOhm), that is, suitable for additional protection of cables when laid in the ground.

Steel - cannot be used for open and hidden electrical wiring in damp rooms and outdoor (street) installations (according to table 2.1.2 on page 138 of PUE-7).

According to clause 2.1.12, this is an attic room in which, according to clause 2.1.74, switching devices (a panel is designed for them) of electrical receivers located in the attic cannot be located.

Which cables are suitable?

For installation in pipes, cables with a plastic or rubber sheath are used according to paragraph 2.3.42. Cables and wires in a polyvinyl chloride sheath are suitable here:

power:

• copper VVG, VVGng, VVGng-LS;
• aluminum AVVG, AVVGng;

control:

• copper KVVG, KVVGE, KVVGng, KVVGEng;
• aluminum AKVVG, AKVVGng;

and others.

For four-wire networks, four-core cables are used. Laying neutral conductors separately from phase conductors is not permissible. There are exceptions for three-core cables according to paragraph 2.3.52.

In one steel and another mechanically strong pipe they lay (according to paragraph 2.1.15):

• all electrical networks of one unit;
• power and control networks of devices connected by the technological process;
• work lighting networks (up to 8 wires);
• emergency evacuation lighting networks (up to 8 wires).

The following cannot be laid in one pipe (according to clause 2.1.16):

• mutually redundant networks;
together networks of working and emergency lighting;
safety extra-low voltage circuits (up to 42 V) and circuits with voltages above 42 V.

How to choose a pipe according to the cable diameter?

Requirements for laying cables in pipes according to PUE-7

When laying pipes under the cable, ensure:

• slope so that moisture does not accumulate (according to paragraph 2.1.63 of PUE-7);
• seals in dusty rooms and in buildings with gases that destroy the sheath or insulation of cables (according to clause 2.1.64 of PUE-7);
• fire safety in compliance with paragraphs 2.1.36; 2.1.39; 2.1.40 and not only these (for example, the use of cables and wires with insulation and sheath made of fire-resistant materials, with the index “ng”).

According to clauses 2.3.105 and 2.3.84, the depth of laying in the ground is 0.7 m (lines up to 20 kV). When crossing streets and squares, 1 m. Reducing the depth to 0.5 m is possible if a line is inserted into a building with a section length of up to 5 m. Laying 6-10 kV lines across arable land at a depth of 1 m (there may be crops on top). In the floors of industrial premises and in closed areas, the laying depth is not standardized.

According to paragraphs 2.3.107 and 2.3.86, clear distances when parallel laying in the ground or floor of a room:

• any (between control cables in pipes);
• 0.1 m (power and control lines with voltage up to 10 kV);
• 0.5 m (to a “foreign” cable or conductor in a pipe).

A slope of at least 0.2% towards the well (to drain trapped water and condensate). According to clause 2.3.22, the tensile force of the cable is determined taking into account the permissible mechanical stresses for the cores:

Power cables (according to table 7-18 of source 2 - reference book)

• with copper conductors – no more than 50 N/mm2;
• with aluminum conductors
• multi-wire – no more than 40 N/mm2;
• single-wire – no more than 20 N/mm2;

Types of clips for fastening wires

When installing open wiring, attaching a wire or cable to the ceiling or wall can be done in various ways. One of the frequently used installation options is based on the use of special fasteners - clips.

Depending on what kind of conductor needs to be laid, whether it is fastened in a pipe, a corrugated sleeve, or openly, whether there are requirements for the appearance of the wiring, clips for wires and cables are used, having different designs and sizes.

Below is an overview of these mounting products.

Clips for mounting corrugated or PVC pipes

In the case when a cable or wire is laid in a corrugated or PVC pipe, it is convenient to use elastic plastic clamps - latches, shown in the photo:

They are made by plastic injection molding and are equipped with stiffening ribs that ensure grip strength on the pipe or corrugation. The use of high-quality plastic allows the product to maintain mechanical characteristics over a wide range of operating temperatures.

Fastening is done with a self-tapping screw. The size range is represented by clips with installation diameters from 12 mm to 50 mm.

A special feature of this product is special grooves on the side surfaces of the clip, thanks to which clips of different sizes can be combined into blocks when parallel laying of several cable lines is necessary.

You should begin work by carefully marking the wiring route. Clips or blocks of them must be attached at equal distances.

If several lines are laid in parallel and the clamps are combined into blocks, there is no need to attach each of them to the wall; it is enough to secure one of the three or four connected clamps.

Depending on the material of the wall or ceiling, the clamp can be attached either by directly screwing in a screw (for wood or drywall) or into a pre-drilled hole (for metal or plastic).

For installation during installation of a cable clamp on brick or concrete, it is better to use a dowel-nail of the required size. The installation ends by installing the pipe into the latch and lightly pressing until it enters the groove, accompanied by a click. We described in more detail how to route the cable through the corrugation in a separate article.

The photo below shows a version of a clamp that secures sealed pipes or corrugations. It is equipped with a clasp that provides a tighter fit. This clamp, like the previous one, is installed under a screw.

GOST standards

Seamless steel pipe for electrical wiring according to GOST is regulated by 8732-78. Their weight is the main indicator for calculating their price. In addition, GOST contains tables that indicate the mass of one linear meter of pipes with thin walls, depending on the wall size and volume. To get a complete understanding of the relationship between such characteristics, you need to carefully study such tables.

Steel water and gas pipes according to GOST 3262-75

Electric-welded straight-seam steel tubes GOST 10704-76 table

Where are steel tubes used in electrical installations?

The most common mistake when laying electrical wiring is turning to resources that direct visitors not to the current GOST standards, but to materials that have long lost their relevance. For example, it is erroneous advice to install PUNP wire, which, in comparison with new products, has a high fire hazard.

Do not forget that errors in wiring, as well as poor insulation, can lead to very serious problems. Any violation of the rules and errors during installation can lead to the fact that the created network will pose a danger to human life.

Therefore, if you have any doubts when choosing pipes for electrical wiring, you can ask for help from specialists. They will help with the choice and, if necessary, carry out installation work.

Corrugated products

Corrugated steel pipe for electrical wiring has a number of advantages over other options for the main line:

Corrugated steel pipes have a long service life. This period is unlimited.
Corrugated steel cuts are characterized by high strength and reliability.
These products for electrical wiring are characterized by increased protection against mechanical influences. To give a specific example, a corrugated pipeline can easily withstand a pressure of sixty-five atmospheres.
Corrugated pipe products are plastic and flexible.
They bend without the use of special tools. It is very important that the cross section remains unchanged. Also, when bent, they will not suffer from the formation of cracks and mechanical stress.
Not affected by corrosion. This is facilitated by a highly alloyed polished steel strip.
Corrugated pipe products are environmentally friendly.
Such a pipeline will not become covered with fungus and mold, and this is an important fact for those rooms where there is high humidity.
To install wiring, you do not need to involve specialists or purchase special tools. All installation activities are easy to carry out on your own.
They are multifunctional. They are widely used not only for electrical wiring, but also in heating systems, plumbing, gas pipelines and fire extinguishing systems.

Video

Corrugated stainless steel pipe Kofulso Neptun (South Korea)

This type of pipe assortment makes it possible to comply with fire safety standards when laying networks using a hidden method. They are also allowed to be used even in wooden buildings with the simultaneous use of other fire-resistant materials, such as asbestos. In such situations, even with a short circuit, no fire will form.

Steel corrugation can be laid in a layer of plaster or under facing coatings that are installed on the frame. For ease of drawing, such products have a steel wire conductor.

Video

Electrical installation pipes for cable laying Obo Bettermann

The presence of standardized fasteners (clips) also greatly simplifies installation (broaching). They are easy to attach to the wall with self-tapping screws, and the workpiece itself is installed by pressing the clip. When it falls into place, a characteristic click appears.

Despite the fact that the appearance of the corrugated network is not very attractive, with some experience, this installation can be done very carefully. In such premises as a house outside the city, a country house, the design of such wiring will be a very practical solution, making it possible to save considerable money.

Application of thin-walled pipes

A few words about the specifics of products of this type. Since we are talking about technical products, its definition should contain numbers, and not a subjective assessment of belonging to one class or another. So: the range of thin-walled steel pipes includes products with a wall thickness of no more than 1.5 millimeters or if the value of the coefficient determined by the formula

Din. is the outer diameter, and S st. – wall thickness, lies in the range of 12.5...40.

A good example of the use of thin-walled metal products includes pneumatic and hydraulic drive systems in the automotive, aviation and shipbuilding industries.

Of course, the above-mentioned area of application for thin-walled steel pipes is far from the only one. They can be found in such industries as:

construction;
housing and communal services sector;
furniture manufacturing;
boiler houses of energy enterprises.

Architectural elements or decorative items can be made from steel pipes

In everyday life, these products are also not uncommon. But here they are most often used when engineering communications must have moderate strength, sufficient to withstand only low loads. In this case, we are talking primarily about a thin-walled steel pipe for electrical wiring.

Corrugated pipes

On sale you can even find varieties of such pipes with very large sections that are laid in concrete or cement screed.

Recommended pipe sizes for various purposes are:

for installation of switches and sockets – 20 mm;
for installation of lighting elements – 16 mm;
laying a line between the boxes and distribution panels - 25 mm;
for making connections between floors – 40 mm.

Let us note the most significant advantages of corrugated pipes for home use:

electrical wiring will be reliably protected from mechanical damage;
possibility of quick installation without additional elements;
non-flammability of the material - thanks to this, the risk of fire of wires is eliminated;
high-quality insulation of electrical wires;
the flexibility of the pipe allows you to create a line of any configuration, passing along the shortest path.

Regulatory documents

Characteristics of copper decorative pipe and additional elements for electrical wiring

The technology of electrical installation work is regulated by a unified set of building codes and regulations, which are mandatory for any organization, production or department.

The following provisions serve as regulatory documents:

PUE (edition No. 7) - rules for the design of electrical installations for new and reconstructed buildings with equipment operating at voltages up to 500 kW.
SNiP (2.08.01–89, 2.09.04–87) – regulations that prescribe general provisions, design standards, installation and work acceptance rules.
PTB (153–34.0–03.150) – safety rules when carrying out electrical installation and debugging work.

The production of steel electrical pipes is regulated by GOST No. 10704–91, 10706–76 and the international standard CEI EN No. 50086–1. GOST contains a complete list of characteristics and technical requirements for the product.

The technical and operational characteristics of rigid smooth PVC pipes are regulated by the interstate standard adopted in 2014 - GOST 32126.1–2013. The old GOST 50827–95 is no longer valid.

Advantages and disadvantages of laying in the soil

Advantages of laying power lines in the soil:

The soil serves to a certain extent as mechanical protection of communications - when laid underground, hurricanes, ice, snow, wind, and the movement of large vehicles are not afraid.
Sometimes overhead installation is simply impossible - if there is a highway or geological obstacles in the way).
Neither ill-wishers nor thieves will damage communications; will not be chewed by rodents and will not be damaged by a cluster of sitting birds.
In the event of a break or short circuit, the earth serves as a grounding conductor - this reduces to a minimum the fire of wiring in the house, the contact of voltage on the building structures and engineering systems (this will protect a person in the event of an accident from injury from electric shock).
Invisible communications do not spoil the design of the site. This is especially true when distributing lighting around the site or the entrance to the site.

Flaws:

Excavation work increases the cost of laying communications, requires time, labor and certain efforts to restore the soil surface - the excavated soil will settle for several years. If the mound is leveled, then in a couple of years a groove will appear in place of the trench.
Laying in pipes is more difficult and more expensive than hanging a cable through the air.
Pipeline installation also complicates the work.
When turning communications, you will have to equip a well.
The most unpleasant thing is that if a cable is damaged, replacing it is quite complicated, takes time, and sometimes is simply impossible (for example, when the soil freezes to a significant depth, it is impossible to dig a trench manually, and digging with an excavator on the site means damaging plantings, sites, possibly a fence or buildings).

Materials for the manufacture of tubes for electrical wiring

The choice of material from which the channel is made depends on the type and characteristics of the room where the wiring is planned.

Pipes can be made from:

plastic;
copper;
brass;
become.

In the manufacture of plastic products, polyvinyl chloride (PVC), high-pressure (HP) and low-pressure (LP) polyethylene (D) are used. Products made from polyvinyl chloride are in high demand among consumers because they have an affordable price and are characterized by good strength and resistance to high temperatures. The most common PVC pipes have a diameter of 16 to 60 millimeters.

Plastic products have a smooth inner surface, and this feature makes it easier to carry out work related to replacing conductors. They are also lightweight and resistant to corrosion. In addition, channels made of polyethylene and polyvinyl chloride are dielectrics and therefore can be considered an additional insulating circuit.

Brass or copper thin-walled tubes are suitable for installation on wall surfaces and for concealed wiring. Such products bend easily and do not require decorative design.

Types of channels for electrical wiring

The choice of tube material depends on the type of room where the wiring is performed, its conditions and features. Among the main channel materials for such purposes are:

plastic;
steel;
copper;
brass.

For the manufacture of plastic models, polyvinyl chloride, high-pressure (H) and low-pressure (D) polyethylene (P) are used. PVC products are the most popular due to their affordable cost, good heat resistance and strength. Common diameters range from 1.6 to 6.0 centimeters.

Plastic pipes are characterized by a smooth surface, which facilitates the work of replacing conductors, low weight, and resistance to corrosion.

Note! PVC and polyethylene channels are dielectrics, which allows them to be considered as an additional insulating circuit.

Thin pipes that are easy to bend are used for laying wires

Metal pipes for electrical wiring, made of steel, have a significant mass, however, they are characterized by particularly high strength. Such products are recommended for use in wooden buildings. Since the material is a good conductor, to ensure electrical safety, all such channels must be grounded. Thin-walled brass or copper tube is excellent for both mounting on wall surfaces and for hidden installation. It bends easily and does not always need decoration.

Plastic or metal? - that is the question

The choice depends on what kind of wiring and under what conditions you plan to carry out. And it also requires relying on the standards prescribed in the PUE. But these are general words, so I’ll go straight to the specifics.

Metal pipes are practically not used in electrical installations

And this is the first thing you need to know. Pipes made of stainless or galvanized steel, aluminum, and brass are becoming less and less common on sale; they are becoming much less in demand and becoming a thing of the past. Mainly due to the inability to compete in cost with plastic analogues with approximately the same performance characteristics.

Where you cannot do without metal hoses is when installing electrical networks in fire hazardous areas: both indoors and outdoors (PUE, Chapter 7.4 “Electrical installations in fire hazardous areas”).

In a wooden building, a galvanized metal hose is required for electrical installation

The work is labor-intensive and financially expensive, but when organizing electrical wiring in a house made of wood, “the game is worth the candle” - or rather, your peace of mind is worth a lot.

That is, a metal hose is more than justified when installing cables in wooden houses, warehouses, and industrial premises where there is an increased risk of fire. But polyethylene, as a flammable material, is categorically not recommended. But it is recommended in most other situations.

External electrical wiring requires different solutions

Here you cannot do without pipes made of low-density polyethylene (HDPE) or polyamide. These are materials that are resistant to frost, moisture, aggressive substances and ultraviolet radiation. They protect the cable from damage during installation and perform the function of fire protection.

HDPE corrugation with broaching probe

Pipes that are visually suitable for outdoor placement are produced in black, as they are minimally susceptible to the destructive effects of ultraviolet radiation.

What if you put it in the ground?

When laying in a trench, it is best to use polyethylene (again, HDPE), and double-walled (two-layer). Why double wall? The outer corrugation helps to achieve high strength and the ability to withstand high loads, and the inner smooth surface ensures quick and easy cable pulling along the entire length.

Double-walled protective red corrugation in a bay

Often pipes for laying in the ground are made in orange or red, which makes sense. The bright color catches the eye and makes it clear that the cable is laid in pipes here, no digging or drilling!

There are two types on sale: non-reinforced and reinforced (more durable, since steel wire is used in their construction). The latter are laid in areas with potentially high compressive loads. As for diameters, when installing in cottage and summer cottage areas, a diameter of 40-50 mm is often sufficient, and for industrial facilities up to 200 mm.

For convenience and clarity, I will collect recommendations in the form of a table

Recommended pipe materials depending on the method of electrical installation

Is it even possible without a pipe? It is possible (read the specific conditions in the PUE), especially if armored cables with high waterproofing characteristics are laid in trenches. BUT it is irrational: laying a simple cable in a protective pipe will cost less than special armored grades.

What pipes are used

Several types of conduit are used to protect cables, including steel, copper, asbestos-cement, concrete, plastic, ceramic and corrugated varieties.

The following pipes are mainly used for electrical wiring:

Polyvinyl chloride pipes (PVC), rigid and flexible (corrugated).
Polyethylene pipes made of low-density polyethylene (HDPE), rigid and flexible (corrugated):
Steel pipes are rigid and flexible metal hoses.

Conditions under which it is possible to use pipes made of PVC, HDPE and metal:

Polyvinyl chloride (PVC) - frost resistance down to -15 ° C, loss of strength when exposed to solar radiation, that is, when laid outdoors (street), it will crumble after winter (only for indoors and buildings).
Made from low-density polyethylene (HDPE or HDPE) – frost resistance down to -45 °C, resistance to chemicals and solvents, dielectric (resistance of at least 100 MOhm), that is, suitable for additional protection of cables when laid in the ground.
Steel - cannot be used for open and hidden electrical wiring in damp rooms and outdoor (street) installations (according to table 2.1.2 on page 138 of PUE-7).

This approach to electrical wiring provides the following advantages:

the wiring is reliably protected from linear stretching, strong compression, as well as from kinks and punctures;
in case of an accidental fire in the room, the wires will not be damaged;
With such protection, sun rays and atmospheric influences are not dangerous for cable insulation.

The described installation method is used for underground work, at industrial enterprises, as well as when laying electrical wiring on the territory and inside fire-hazardous objects.

Some installation rules

Before installing a cable route made of thin-walled metal pipes for electrical wiring, you should familiarize yourself with the following rules:

the ends of each piece of products need to be pre-cleaned from burrs and countersinked; the maximum permissible bending angle of the steel channel is 90 degrees; there is a limitation on the length of the sections: up to 10 meters in the case of a straight pipe, up to 5 meters - if there are 2 bends; When bending, it is important to monitor the integrity of the cross-section of the product; the metal channel must be made as part of the EPS (potential equalization system).

If it is impossible to meet the conditions for choosing the length of the pipes, according to the rules, it is necessary to install a pull-out box without additional joints.

The physical essence of the control system is the need to connect all conductive parts into a single system in such a way as to minimize or completely eliminate the potential difference between them. To do this, it must include:

grounding device;
main (D) grounding (G) bus (W), mounted in the electricity metering (U) board (E) or input board;
All elements of the building's structure are made of metal.

If you adhere to these rules, you can significantly simplify the installation and replacement of electrical wiring.

Application of metal pipe products

When metal pipes are used for electrical wiring, there may be difficulties associated with pulling the cable through them. This can be solved in several ways. The simplest of them is to insert a steel wire into the channel, attach a cable to its end and then pull it inside.

If the pipe is long, then you can place a ball in it, to which a strong ribbon or thread is tied. To make it easier to move, talc is used. A steel wire is attached to the end of the tape and the air compressor pipe is placed in the hole, after which the device is turned on. The ball moves under pressure along the channel and draws the tape or thread along with it. To cut the product, use a grinder or a hacksaw.

To lay electrical wiring to sockets and switches, choose products with a diameter of 20 millimeters, for lighting fixtures – 16 millimeters, 25 millimeters for connecting distribution or switchboards and boxes, and for interfloor connections – 40 millimeters. The length of the channels, as a rule, ranges from 3 to 5 meters.