Zero protective and zero working conductors differ in purpose, connection method and functional load in electrical networks.

Zero working conductor

The neutral working conductor is a network conductor connected to the solidly grounded neutral of a three-phase transformer or the neutral terminal of a single-phase transformer. The load current flows through the neutral working conductor. In the diagram, the neutral working conductor is designated by the letter “N”.

Neutral protective conductor

In the diagrams, the neutral protective conductor is designated by two Latin letters “PE”. In normal operation of the electrical network, no electric current flows through the neutral protective conductor.

In the diagrams, the letters PE indicate not only the neutral protective conductor, but also all protective conductors of the network: grounding conductors, protective conductor in the potential equalization system, individual cores in cables, separately laid conductors and busbars.

Separation of protective and working zeros of the electrical network

In an electrical network with a solidly grounded neutral TN, the neutral working conductor N and the protective conductor PN, up to a certain point in the electrical network, are combined into one conductor and this conductor is designated by the letters PEN.

The separation of the PEN conductor is usually carried out on the GZSh-main grounding bus, which is installed at the input of the electrical installation) next to the branch to the house (on a pole) or in the house in the input distribution device (IDU).

Zero protective and zero working conductors - conclusions

• The zero working conductor (neutral), together with the phase conductor, participates in the power supply of devices. A working current flows through it;
• The neutral protective conductor does not participate in the power supply and is intended for protection against indirect contact in networks with a solidly grounded neutral.

Sources electrical systems, installed in houses and apartments, are stations and generators consisting of three windings and phase conductors. To avoid problems with the use and maintenance of the electrical network during the operation of your home, you need to know what phase, zero and ground are in the electrical wiring of the apartment.

The figure below shows a diagram of splitting a three-phase network into single-phase ones.

In addition to 3 phases and 1 zero, the cable also has grounding, therefore a wire with five cores is supplied from the substation to the objects. A single-phase input having a phase, neutral and grounding is laid from the communal panels to the switchgear of individual apartments. Due to this, we have a voltage of 220 V in the network, and not the original 380 V. In the process of transmitting electricity, only two conductors are involved - phase and zero, grounding has another function, which is to ensure the safety of operation of the electrical network in the event of emergency situations - breakdowns in insulation or leakage currents.

In a three-phase circuit, the voltage level between any two phases is 380 V, between phase and zero - 220 V.

In the common building electrical panel zero and ground are connected and connected to established circuit grounding. These conductors are laid separately to the distribution boards of apartments. In floor switchgears, zero is connected to special contact, and the grounding is connected to the electrical panel housing.

Household electrical networks use alternating current with a frequency of 50 Hz. It flows between the neutral and phase conductors, changing its direction 50 times per second.

Zero and phase are connected to the consumption points of the apartment. Conductor, but through special contacts.

When working with an electrical network, you must remember that when a phase comes into contact with the human body, it will pass through the body electric charge, capable of causing significant harm to health. That is why the installation of sockets and switches can only be done when the power supply line in the apartment is de-energized.

If an electrical device with pulse block power supply, electric current can also pass through the neutral conductor, although due to the low voltage level it rarely poses a danger to humans.

Marking and identification of phase, zero and ground

In electrical cables, the phase, neutral and ground conductors have insulation of different colors. Marking of wires is required to ensure the safety of electrical installation work - laying electrical cables and installing consumption points. Conductors are marked in accordance with modern requirements of PUE and GOST.

The insulation of the grounding conductor must be painted yellow-green. Some manufacturers produce cables in which the ground is purely yellow or purely green. Sometimes ground insulation is marked with yellow-green stripes. On electrical diagrams grounding is designated by the Latin letters PE.

The neutral conductor, also called neutral, must have blue or light blue insulation. In diagrams, zero is usually denoted by the Latin letter N.

The most difficult situation is with the phase conductor. Various manufacturers use black, white, brown, grey, red, orange, turquoise, pink or purple insulation for the phase. The most common types are black, white and brown conductors. The phases are designated in the diagrams by the Latin letter L. In 380 V networks, cables also have a numerical value: L1, L2, L3.

If it is difficult to determine the type of conductor from the markings, you can always use an indicator screwdriver. With its help, it is easy to find phase and neutral in a socket or electrical cable. When using indicators, be sure to remember safety precautions.

There are two types of electrical networks. Networks AC and DC networks. Electric current, as is known, is the ordered movement of electrons. In case DC they move in the same direction and... as they say, they have constant polarization. In the case of alternating current, the direction of movement of electrons changes all the time, that is, the current has alternating polarization.

The AC network is divided into two components: the operating phase and the empty phase. Working phase sometimes simply called phase. They call it empty zero phase or simply zero. It serves to create a continuous electrical network when connecting devices, as well as to ground the network. And the operating voltage is supplied to the phase.

When turning on an electrical appliance, it does not matter which phase is working and which is empty. But when installing electrical wiring and connecting it to the general house network, this needs to be known and taken into account. The fact is that the installation of electrical wiring is done using either a two-core cable or a three-core cable. In a two-core one, one core is the working phase, the second is zero. In a three-wire system, the operating voltage is divided into two wires. This results in two working phases. The third core is empty, zero. The general house network is made of a three-core cable. A common or apartment connection is also usually made from three-core wire. Therefore, before connecting apartment wiring, you need to determine the working and zero phases.

Methods for determining phase and neutral wires

It is not difficult to find out which core is receiving voltage and which is not. There are several ways to determine phase and zero.

First way. Phases are defined according to the color of the core shell. Typically, the working phases are black, brown or gray, and the zero is light blue. If additional grounding is installed, its core is green.

In this case, no additional devices are used to determine the phases. Consequently, this method is not very reliable, because when installing the wiring, electricians may not comply with the color coding of the cores.

It is more reliable to determine phases using electric indicator screwdriver. It is a non-conducting housing in which an indicator and are built-in. A neon light bulb is used as an indicator. When the tip of a screwdriver touches a bare, live wire, the indicator, if the wire is working, lights up. If it's zero, it doesn't work. Using such a screwdriver, you can determine the health of the network. If, when the tip touches one wire at a time, the light does not light up, then the network is faulty.

It happens that the indicator lights up when you touch both conductors of the wire, that is, both the phase and the neutral. This means that there is a break somewhere in the empty phase. It needs to be found and eliminated.

Phase detection can be done multimeter. First we set the measurement mode – alternating voltage. Then we hold the end of one probe in our hand. We touch the core with the second probe. If the phase is working, the voltage value will be shown on the device screen.

You can determine the working phase using the usual light bulb. We take it, screwed into the socket, with two pieces of wire. We ground one end. You can ground it by screwing it to the heating battery. The ends of the wires, of course, should be bare. We touch the core with the other end. If the light comes on, then the phase is working.

One of the methods showing what phase and zero are in electrical engineering, in the video

The neutral working conductor is also called neutral. Most household appliances are powered by an alternating 220 V network. In order to supply this voltage to them, one phase wire is used, and the second is neutral. The phase has a potential of 220 V, and the neutral wire has a potential of 0 relative to the power source and the phase wire.

Zero is designated as N, and its insulation should be blue or white-blue, in accordance with. Often the functions of the neutral working wire and the protective wire are combined (for). This joint conductor is designated PEN and has yellow-green insulation with blue markers (tags) at the ends. Similar color designations are used in Europe. In the US, the neutral working wire may be designated white or gray.

Different networks can use different neutrals (isolated, solidly grounded, effectively grounded). The choice of one option or another is determined functional purpose networks.

IN present moment Almost all residential buildings in Russia have grounding systems with a solidly grounded neutral. In this case, electricity is supplied from three-phase generators in 3 phases with potential, and also a fourth wire comes from the generator - neutral (working zero). The three phases at the end of the line are connected in a star: this creates the end of the neutral, which is connected to the neutral of the supply generator. The wire connecting these two neutrals is called the working neutral conductor of the network.

In case symmetrical load for all phases in the working zero is absent. If the load is distributed unevenly, then an unbalance flows along the zero working conductor. The use of such a scheme makes it possible to achieve self-regulation of all three phases, while they are almost equal to each other.

To increase safety, the working zero is at the end of the line, and additional grounding is often used: at the beginning of the line and at its different points. In houses, the neutral working wire is supplied to a switchgear, from which separate neutral conductors already go to direct consumers of electricity (for example, to apartments).

In addition to networks with a solidly grounded neutral, they are also used with an isolated neutral. In such networks there is no neutral working wire. Instead, if necessary, a neutral grounded wire can be used.

When using three-phase power lines in a building, the cross-section of the neutral working conductor must be no less than the cross-section of the phase conductors, with sizes of the latter up to 25 mm2 (aluminum). If the cross-section of the phase conductors is more than 25 mm2, then the cross-sectional area of ​​the working zero must be at least 50% of their cross-section. If the network uses a grounding working zero, then when connecting the wire to the main grounding bus, the identification sign “ground” must be present.

Even if the protective and working zeros are connected at the switchgear, their further combination at consumers is not allowed. That is, further through the apartments two separate wires PE and N are run. They cannot be connected because when the phase is closed to the neutral working conductor, and all devices connected to the protective conductor PE (in the case of combining PE and N) will be under the phase conductor voltage, which creates a high probability of electric shock to a person.

It is known that electrical energy is generated at power plants using alternating current generators. Then, through power lines from transformer substations, electricity is supplied to consumers. Let's take a closer look at how energy is supplied to the entrances of multi-storey buildings and private houses. This will make it clear to even novices in electrics what phase, zero and grounding are and why they are needed.

Simple explanation

So, to begin with in simple words We will tell you what a phase and neutral wire is, as well as grounding. A phase is a conductor through which current comes to the consumer. Accordingly, zero serves to ensure that the electric current moves in the opposite direction to the zero circuit. In addition, the purpose of zero in electrical wiring is to equalize phase voltage. The grounding wire, also called ground, is not live and is designed to protect a person from electric shock. You can find out more about it in the corresponding section of the site.

We hope our simple explanation helped you understand what zero, phase and ground are in electrical engineering. We also recommend studying to understand what color the phase, neutral and grounding conductors are!

Let's delve into the topic

Consumers are powered from the low voltage windings of a step-down transformer, which is the most important component of the operation of a transformer substation. The connection between the substation and subscribers is as follows: a common conductor is supplied to the consumers, extending from the point of connection of the transformer windings, called the neutral, along with three conductors, which represent the terminals of the remaining ends of the windings. In simple terms, each of these three conductors is a phase, and the common one is zero.

Between phases in a three-phase power system, a voltage called line voltage occurs. Its nominal value is 380 V. Let's define phase voltage - this is the voltage between zero and one of the phases. The rated phase voltage is 220 V.

An electrical power system in which the neutral is connected to ground is called a “solidly grounded neutral system.” To make it absolutely clear even for a beginner in electrical engineering: “ground” in the electrical power industry means grounding.

The physical meaning of a solidly grounded neutral is as follows: the windings in the transformer are connected in a “star”, and the neutral is grounded. The neutral acts as the combined neutral conductor (PEN). This type of connection to the ground is typical for residential buildings dating back to Soviet construction. Here, in the entrances, the electrical panel on each floor is simply nulled, and a separate connection to the ground is not provided. It is important to know that connecting the protective and neutral conductors to the panel body at the same time is very dangerous, because there is a possibility that the operating current will pass through zero and its potential will deviate from zero, which means the possibility of electric shock.

For houses belonging to a later construction, the same three phases, as well as separated neutral and protective conductors, are supplied from the transformer substation. The electric current passes through the working conductor, and the purpose of the protective wire is to connect the current-carrying parts with the ground loop existing at the substation. In this case, in electrical panels On each floor there is a separate bus for separate connection of phase, neutral and grounding. The grounding bus has a metal connection with the body of the shield.

It is known that the load among subscribers must be distributed evenly across all phases. However, it is not possible to predict in advance what power will be consumed by a particular subscriber. Due to the fact that the load current is different in each individual phase, a neutral offset appears. As a result, a potential difference arises between zero and ground. In the case when the section neutral conductor is insufficient, the potential difference becomes even greater. If the connection with the neutral conductor is completely lost, then there is a high probability of emergency situations in which in phases loaded to the limit, the voltage approaches zero, and in unloaded phases, on the contrary, tends to a value of 380 V. This circumstance leads to complete breakdown of electrical equipment . At the same time, the housing of electrical equipment becomes energized, dangerous to the health and life of people. The use of separated neutral and protective wires in this case will help avoid such accidents and ensure the required level of safety and reliability.