Electricity supply. Open and hidden wiring. Which wiring is better, hidden or open - comparison of methods What is open and closed wiring

Electrical wiring refers to all electrical wires and cables installed in a house or apartment. They are designed to supply electricity to household and lighting appliances. Today we are nowhere without technology, so let's take a closer look at all these cables and junction boxes.

Types of Electrical Wiring

There are two types electrical wiring: hidden and open.The structure of the wiring itself, regardless of its type, is always the same: inapartment or house, the main power cable is introduced, which is connected to electric meter. Power supply cables extend from the meter to all rooms. In rooms, cables branch out even more: to sockets, to switches, to lighting fixtures.

1. Hidden wiring

The name itself hidden wiring implies that electrical cables are hidden inside walls, partitions and ceilings, they are not visible. Only intermediate or end points are visible to our eyes: distribution boxes, switches, lighting fixtures, sockets and meters.

Hidden wiring is used in modern panel, monolithic and brick houses. Electrical cables are located in special channels inside walls or behind decorative or plasterboard panels.

The cable channel is an ordinary PVC tube, which is poured inside the panel or laid in specially cut grooves in the walls or ceiling. Such channels usually end in installation boxes into which sockets and switches are mounted.

The main advantage of hidden wiring is its invisibility. But repair, replacement and redevelopment, especially in monolithic or brick houses, is a rather troublesome procedure: you have to open the walls, and after replacing them, cover them up and paint over them again.

2. Open wiring

Exposed wiring is located on top of a wall or ceiling. But open does not mean “unprotected”. For open wiring, either ready-made cable ducts (cable runs) or PVC pipes into which the wires are laid are used in the same way.In some cases, open wiring is done with double or even triple insulated cables. For example, they do wiring in dachas and country wooden cottages.For open wiring, special sockets, switches and distribution boxes are used. They have a closed body and are mounted directly on the wall.

Interior designers sometimes use exposed wiring as a decorative element, for example, when implementing a project in a steampunk, country or loft style. For such projects, multi-colored wires and cables, fabric-braided wires, and special designer fasteners are used.

An important advantage of open wiring is that its repair, replacement or connection of new branches is carried out without much labor: there is no need to hollow out the walls and restore them after work. The downside is that the wiring is visible, but for some, this minus can be a plus.

Wire types

Cables and wires are used for laying electrical wiring. For a non-specialist, there is not much difference between these concepts, but when laying wiring it is important to know what it will be done with: cable or wire.

Wire

A wire is one solid wire metal core. The wires may be bare or coated with a layer of insulating material. They are also divided into bottom-haired (monolithic) and multi-haired (braided). The first ones are used for hidden wiring. Braided wires are more flexible and less susceptible to frequent bending and twisting, which is why they are often used to power household appliances.

1. PVS wire

This wire is often used to repair electrical networks. It is also suitable for making extension cords and cords for any type of equipment. Flexibility and lightness make PVA an indispensable assistant for lighting and installation of sockets To.

2. PBPP wire

Flat electrical wire with two or three solid copper cores. This is a universal conductor electric current, high quality: BPPP can be used when carrying out electrical installation work in a private house, apartment or country house. It is suitable for connecting lighting as well as mounting electrical outlets and switches.

Cable

Cable is several insulated wires in general protective insulation. The number of wires in the cable may vary. For household electrical wiring, two-, three- and four-core cables with a cross-section from 2.5 to 4 mm are used.

Wires and cables for household electrical wiring are made of copper or aluminum. In older houses that are more than 15 - 20 years old, aluminum wiring was previously used. Modern houses equipped with copper cables: with the same wire cross-section copper cables able to withstand large electrical loads. In addition, copper cables are more flexible and less susceptible to oxidation.

Important: try to avoid connecting copper and aluminum wires. At the point of such contact occurs chemical reaction oxidation with release large quantity heat. Possible fire. Use cables made of the same material.

1. CableNYM

High-quality German cable consisting of 1-5 cores. It is used for laying lighting and power networks both indoors and outdoors. His distinguishing feature – high degree security. This cable is also moisture and heat resistant, but does not like sunlight, so it must be protected from direct rays.

2. VVG cable

Cable with excellent insulation characteristics. It consists of one core, making it convenient to install inside walls. Most often, VVG is used when independently installing or replacing electrical wiring in an apartment. The service life of such a cable is at least 30 years.

Wiring for powerful equipment

For household electric stoves and electric ovens, it is recommended to lay a separate electrical wiring branch. For this branch, more powerful cables with copper conductors in double insulation, with a cross-section of at least 6 mm, are used, and special power sockets are installed.

Distribution boxes

To organize the electrical network of a house or apartment, distribution boxes, or, as they are also called, distribution boxes, are used. They are installed at junctions, or, if you like, branches of individual electrical wiring cables. There are such boxes in every room. They are usually located under the ceiling. There are two types of distribution boxes: d For hidden and outdoor installation.

Hidden distribution boxes are recessed into special sockets under the ceiling, at the convergence of several cable channels. The main power cable comes into the box, and cables for powering sockets, a cable for a switch, cables for power branch off from it lighting fixtures: chandeliers, sconces, sections of spots, etc..Open boxes are mounted directly on the wall in the most convenient place for this.

Which wiring is better for an apartment?

There are two ways to bring electricity to an Ilyich light bulb or a modern LED - using hidden or open wiring. Each of these methods has its own disadvantages, and they are not without advantages. We will sort out their pros and cons, and see which wiring is best for different rooms, which will help the owner of the apartment to say out loud “let there be light.”

It would be more correct to pose the question not “which wiring in the apartment is better,” but which is more rational, but this does not change the essence. To the point.

Hidden wiring

Hidden wiring is a classic in the home electrification genre. It’s not worth talking about this method for a long time, since it is well known to everyone since the age of 10, but briefly you can describe it like this:

1. - A groove is made in the wall or ceiling,
2. - The cable can also run through the voids of floors without gating,
3. - The gate goes from the distribution box to the end point (switch, socket),
4. - A wire is laid in the channel,
5. - The wire is fixed with gypsum plaster,
6. - The ends of the wire are connected to the box and the socket or switch.

Advantages of hidden wiring :

1. - External boxes do not spoil the interior,
2. - The cable is difficult to accidentally damage, for example, when moving furniture.

1. - Dirt when punching grooves,
2. “If the wire burns out, you’ll have to hammer into the wall again.”

Hidden wiring is always started before finishing begins, the grooves are sealed gypsum mixture and then they are puttied, painted, or other executions are performed on the walls and ceiling. If necessary, you can later find such wiring using a detector, so it is not necessary to draw exact network plans.

Open (external) wiring

Such wiring does not go inside the walls, but outside, hidden in cable channels. This method of electrifying an apartment is in some ways better, in others worse.

Description of open wiring stages :

1. - Between the distribution box and the end point of energy consumption, a cable channel is fixed on dowels and nails,
2. - The wire is placed in the channel, its cover is snapped on,
3. - The ends of the cable are connected into a single circuit.

Pros of external wiring :

1. - Minimum dirt during installation,
2. - The wire is easy to change,
3. - It’s easy to make a branch to another electrical point.

1. - Not everyone likes the look of cable channels,
2. - When remodeling an apartment, you can damage the box and the wire in it.

Comparison of methods

You can compare these wiring methods only taking into account the aesthetic taste of the apartment owner; if you put aesthetics in the chest of drawers and consider the purely technical part, then:

1. - Walls made of soft material, for example, gas silicate, it is better to chisel - this can be done with a hammer drill and a common chisel,
2. - Running a box along the ceiling is not an ideal option for an apartment,
3. - The cable channel is best used for wiring in the hallway or kitchen along concrete walls,
4. - If preference is given to the open method, then choose the optimal box, taking into account the interior, color and size,
5. - In the nursery, you don’t see the box at the bottom - you don’t yet know all the design capabilities of your child.

Often hidden and open ways the wiring is combined - this is permissible, but the connection of wires from different materials(copper and aluminum) not directly best option. With such a connection, the wires can burn out at the point of contact, and it’s good if this happens outside the wall. To connect wires made of different materials, use an adapter washer and make the connection in an accessible place, for example, in distribution box, and not in the depths of the groove.

http://stroyremontiruy.ru

Vitaly
Good afternoon What explains such a significant difference in the permissible values ​​of current flowing through a cable of the same cross-section when open and closed types wiring?

Answer:

Wires or cables laid openly (exposed wiring) cool better than wires and cables (hidden wiring) laid in pipes or hidden under plaster, suspended ceiling and behind hemmed walls. Wires with rubber insulation allow long-term heating of their cores, not exceeding 65 °C, and wires with plastic insulation - 70 °C. The cross-section of the current-carrying conductors is selected based on the maximum permissible heating of the conductors, at which the insulation of the wires is not damaged.

If you cannot carry out electrical measurements yourself, then use the services of specialists from a mobile electrical laboratory.

Electric current in metals is the ordered movement of electrons under the influence of electric field. The most convincing evidence of the electronic nature of current in metals was obtained in experiments with the inertia of electrons (the experiment of Tolman and Stewart):

A coil with a large number of turns of thin wire (Fig. 9.1) was driven into rapid rotation around its axis. The ends of the coil were connected using flexible wires to a sensitive ballistic galvanometer. The untwisted coil was sharply slowed down, and a short-term current arose in the circuit due to the inertia of the charge carriers. The total charge flowing through the circuit was measured with a galvanometer. When braking a rotating coil, each charge carrier e with mass m is acted upon by a braking force, which plays the role of an external force, that is, a force of non-electric origin:

The external force per unit charge is, by definition, the field strength of the external forces:

Consequently, in the circuit when the coil is braking, an electromotive force arises:

During the braking of the coil, a charge q will flow through the circuit equal to:

where is the length of the coil wire, I is the instantaneous value of the current in the coil, R is the total resistance of the circuit, and is the initial linear speed of the wire. The good electrical conductivity of metals is explained by the high concentration of free electrons, equal in order of magnitude to the number of atoms per unit volume. The assumption that electrons are responsible for the electric current in metals arose much earlier than the experiments of Tolman and Stewart. Back in 1900, the German scientist P. Drude, based on the hypothesis of the existence of free electrons in metals, created the electronic theory of metal conductivity. This theory was developed in the works of the Dutch physicist H. Lorentz and is called classical electronic theory. According to this theory, electrons in metals behave like an electron gas, much like an ideal gas. Electron gas fills the space between the ions that form the metal's crystal lattice. Due to interaction with ions, electrons can leave the metal only by overcoming the so-called potential barrier. The height of this barrier is called the work function.
At ordinary (room) temperatures, electrons do not have enough energy to overcome the potential barrier. According to the Drude–Lorentz theory, electrons have the same average energy of thermal motion as the molecules of a monatomic ideal gas. This allows us to estimate the average speed of thermal motion of electrons using the formulas of molecular kinetic theory:

When an external electric field is applied to a metal conductor, in addition to the thermal movement of electrons, their ordered movement (drift), that is, an electric current, occurs. The electron drift velocity is in the range of 0.6 – 6 mm/s. Thus, the average speed of the ordered movement of electrons in metal conductors is many orders of magnitude less than the average speed of their thermal movement. The low drift speed does not contradict the experimental fact that the current in the entire circuit DC installs almost instantly. Closing the circuit causes the electric field to propagate at a speed c= 3·10 8 m/s. After time (l is the length of the chain), a stationary distribution of the electric field is established along the chain and the ordered movement of electrons begins in it.
In the classical electronic theory of metals, it is assumed that the movement of electrons obeys Newton's laws of mechanics. In this theory, the interaction of electrons with each other is neglected, and their interaction with positive ions is reduced only to collisions. It is also assumed that with each collision the electron transfers to the lattice all the energy accumulated in it. electric field energy and therefore after the collision it begins to move with zero drift speed. Despite the fact that all these assumptions are very approximate, the classical electronic theory qualitatively explains the laws of electric current in metal conductors: Ohm's law, the Joule-Lenz law and explains the existence electrical resistance metals
Ohm's Law:

Electrical resistance of the conductor:

Joule-Lenz law:

However, in a number of issues, the classical electronic theory leads to conclusions that are in conflict with experiment. This theory cannot, for example, explain why the molar heat capacity of metals, as well as the molar heat capacity of dielectric crystals, is equal to 3R (Dulong and Petit's law). Classical electron theory also cannot explain temperature dependence resistivity of metals: theory gives, while from experiment the dependence ρ ~ T is obtained. The most striking example of the discrepancy between theory and experiments is superconductivity. The qualitative difference between metals and semiconductors (dielectrics) lies in the nature of the dependence of specific conductivity on temperature. For metals, the conductivity decreases with increasing temperature, while for semiconductors and dielectrics it increases. At T o K, pure metals have conductivity s o ¥. For semiconductors and dielectrics at T o K, s o 0. There is no qualitative difference between semiconductors and dielectrics with regard to electrical conductivity. The manifestation of metallic properties in some substances, and semiconductor and dielectric properties in others, can be consistently explained only within the framework of quantum theory.
According to quantum concepts, the energy of electrons in an atom can change in a discrete manner. Moreover, according to the Pauli principle, there can be no more than one electron in one quantum state. As a result, electrons are not collected at any one energy level, but sequentially fill the allowed energy levels in the atom, forming its electron shells. When approaching large number atoms and the formation of a crystal structure chemical bonds between atoms are formed due to electrons located in the outer, valence, electron shells.
According to the Pauli principle, atoms cannot bunch together into a dense mass, since in this case there would be many particles with half-integer spin in one quantum state - the intrinsic angular momentum (L = ħ/2). Such particles are called fermions, and they include, in particular, electrons, protons, and neutrons. They are named after the Italian physicist E. Fermi, who was the first to describe the peculiarities of the behavior of groups of such particles. When a large number of atoms come together within solid the initial energy level of the valence electron in the atom is split into N sublevels, where N is the number of atoms forming the crystal. As a result, a zone of allowed energy levels for electrons in a solid is formed (Fig. 9.2).

Fig.9.2
In metals, the outer valence shells are not completely filled, for example, silver atoms have one electron in the outer shell 5s1, while, according to the Pauli principle, there could be two electrons with different spin orientations, but the second electron in the outer shell of the silver atom is simply No. When N Ag atoms approach each other and the outer energy level 5 splits s 1 1 into N sublevels, each of them is filled with two electrons with different spin orientations. As a result, when N silver atoms approach each other, an energy band appears that is half filled with electrons. The energy corresponding to the last filled electronic level at 0 K is called the Fermi energy eF≈kTg. Distance between adjacent energy levels DE is very small because N is very large, up to.
e F ~ 1¸10 eV, Δ E=eF/ N << kT» 0.025 eV.

The distance between adjacent allowed levels of electrons in metals is much less than the energy of thermal motion of electrons even at the lowest temperatures. If you place a conductor in an electric field, turning it on, for example, in a closed circuit with an EMF source, then electrons will begin to move from a point in the conductor with a lower potential to a point with a higher potential, since their charge is negative. But movement in an electric field means an increase in the energy of the electron, and according to quantum concepts, a transition to a higher energy level of an electron is possible if this neighboring level is free. In metals, there are quite enough such free levels for electrons located near the Fermi level, so metals are good conductors of electric current.
However, this conductivity is provided not by all free electrons of the metal, but only by those located near the Fermi level. The concentration of such electrons is approximately equal to nT /Tg, Where Tg= 5×10 4 K– degeneration temperature.

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There are two ways to bring electricity to an Ilyich light bulb or a modern LED - using hidden or open wiring. Each of these methods has its own disadvantages, and they are not without advantages. We will sort out their pros and cons, and see which wiring is better for different rooms, which will help the owner of the apartment to loudly say “let there be light.”

It would be more correct to pose the question not “which wiring in the apartment is better,” but which is more rational, but this does not change the essence. To the point.

Hidden wiring

Hidden wiring is a classic in the home electrification genre. It’s not worth talking about this method for a long time, since it is well known to everyone since the age of 10, but briefly you can describe it like this:

1. — A groove is made in the wall or ceiling,
2. — The cable can also run through the voids of floors without gating,
3. — The gate goes from the distribution box to the end point (switch, socket),
4. — A wire is laid in the channel,
5. — The wire is fixed with gypsum plaster,
6. — The ends of the wire are connected to the box and the socket or switch.

Advantages of hidden wiring:

1. — External boxes do not spoil the interior,
2. — The cable is difficult to accidentally damage, for example, when moving furniture.

Cons:

1. — Dirt when punching grooves,
2. “If the wire burns out, you’ll have to hammer into the wall again.”

Hidden wiring is always started before finishing begins; the grooves are sealed with a gypsum mixture and then puttyed, painted, or other executions are performed on the walls and ceiling. If necessary, you can later find such wiring using a detector, so it is not necessary to draw exact network plans.

Open (external) wiring

Such wiring does not go inside the walls, but outside, hidden in cable channels. This method of electrifying an apartment is in some ways better, in others worse.

Description of open wiring stages:

1. — Between the distribution box and the end point of energy consumption, a cable channel is fixed to dowels and nails,
2. — The wire is placed in the channel, its cover is snapped on,
3. — The ends of the cable are connected into a single circuit.

Pros of external wiring:

1. — Minimum dirt during installation,
2. — The wire is easy to change,
3. — It’s easy to make a branch to another electrical point.

Cons:

1. — Not everyone likes the look of cable channels,
2. — When remodeling an apartment, you can damage the box and the wire in it.

Comparison of methods

You can compare these wiring methods only taking into account the aesthetic taste of the apartment owner; if you put aesthetics in the chest of drawers and consider the purely technical part, then:

1. — Walls made of soft material, such as gas silicate, are better to be chipped - this can be done with a hammer drill and a common chisel,
2. — Running a box along the ceiling is not an ideal option for an apartment,
3. — The cable channel is best used for wiring in the hallway or kitchen along concrete walls,
4. — If preference is given to the open method, then choose the optimal box, taking into account the interior, color and size,
5. — In the nursery, you don’t see the box at the bottom - you don’t yet know all the design capabilities of your child.

Often hidden and open wiring methods are combined - this is acceptable, but connecting wires made of different materials (copper and aluminum) directly is not the best option. With such a connection, the wires can burn out at the point of contact, and it’s good if this happens outside the wall. To connect wires of different materials, use an adapter washer and make the connection in an accessible place, for example, in a junction box, and not deep in the groove.

Electrical wiring installed at home may be open or closed. If we talk about open wiring, it is performed as follows.

Open wiring

The wiring is carried out along the wall, in a plastic pipe, in a special cable plinth, in a special cable plastic channel. As for the height of open laying of protected cables and wires, descents and ascents of such laying to panels, switches, starting devices and lamps that are installed on the walls, they are not standardized. When performing open electrical wiring in a cable plinth and channel, power, lighting and low-current wires do not mix with each other. Fixing the plinth or channel should ensure a sufficiently tight fit to the building foundations, and also provide a gap between the plinth and the floor or the channel and the wall covering - no more than two millimeters. Skirting boards with channels must be purchased from fireproof and self-extinguishing materials that have electrical insulating characteristics. Cable channel modules and cable plinths can be used in a residential building if a flexible layout for the installation of lamps, as well as lighting control devices, is provided. Such devices allow you to change wiring layouts and place electrical equipment, sockets and switches differently. In basements that are not heated, in closets and attics, in rooms that are built from wooden structures, electrical wiring is done openly using staples.

Closed wiring

But you can do the wiring in a hidden way - in the cavities of building structures, above suspended ceiling coverings, in prefabricated partitions, in grooves made in wall coverings, in embedded pipes. Horizontal places for power cable distribution are laid in the floor covering, which is made of non-combustible materials, such as “warm floors”.

Processes of laying wiring under the plaster layer, in partitions, in cavities of building structures

If you decide to lay the wiring of lighting networks embedded in the grooves of wall coverings, partitions, ceilings, under plaster or in the cavities of building structures, then it is recommended to use insulated cables or wires in a common protective sheath, which provides mechanical protection. If it is necessary to dismantle such a gasket, it is necessary to do the repair almost all over again. Therefore, before choosing this method, you need to do a good calculation.