Why do you need a neutral conductor? Zero protective and zero working conductors. Indicator screwdriver to help

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 working 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 phase is supplied operating voltage.

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 cartridge, 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

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 along the neutral protective conductor electric current doesn't flow.

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.

In the process of installing an electrical network in an apartment or house, you will inevitably face the question of what is a neutral wire and grounding and what is their difference? After all, without a clear understanding of this issue, install electrical network, fully complying with the standards of the PUE (Electrical Installation Rules) is quite difficult. Therefore, in our article we will try to understand this issue and provide the basic rules for installing these circuits.

First of all, let's figure out what a neutral wire is and what a protective wire is, what are their differences and what is their purpose? Based on this, it will be easier for us to understand the rules for connecting them and the requirements that the PUE imposes on them.

What is a neutral wire

First of all, let's focus on the neutral wire, or as it is also called the neutral wire. According to clause 1.7.35 of the PUE, it is intended to power electrical receivers and is connected to the solidly grounded neutral of the transformer.

If we talk in simple language and discard some nuances that are not so important for us, the neutral wire is a conductor connected to the grounded part of the transformer or generator from which you receive power.
In a single-phase network, which is used in almost all private households and apartments, a phase and neutral wire is required for the operation of electrical installations. The neutral wire is essentially directly connected to ground and ideally has zero potential. That is, there is no voltage on it.

Pay attention! There is no voltage on the neutral wire if it is connected to ground. If this connection is broken for any reason, then during the operation of the electrical installation it turns out to be under voltage equal to the phase voltage. That is, for a single-phase network equal to 220V.

In the diagrams, the neutral wire is indicated by the symbol “N”. The old Soviet instructions recommended using the designation “0” and it can still be found on some diagrams. And the wire itself, according to clause 1.1.30 of the PUE, must be made of blue wire.

What is grounding?

Grounding or protective conductor in accordance with clause 1.7.34 of the PUE is intended exclusively for electrical safety purposes. Under normal conditions, it is not energized and acts as a conductor only in cases of failure of the insulation of the phase or neutral conductor. At the same time, at the electrical installation itself, it reduces the potential to bladeless.

In simple terms, grounding is necessary only in case of breakdown. For example, you have a breakdown in the insulation of your washing machine. If it is not grounded, then touching it is equivalent to touching a phase wire. If it is grounded, then nothing will happen, since the excess potential will go into the ground through grounding.
Grounding can be done using different schemes depending on your capabilities and the power supply circuit. This question we'll look at it below.
The protective conductor in the diagrams is usually designated by the symbols “PE”. The conductor itself should be made of yellow-green wire.
On some diagrams you may see the designation “PEN”. This means the combination of the neutral and protective wires. We'll talk about it a little lower. The color of such a wire, according to clause 1.1.29 of the PUE, should be blue with yellow-green stripes at the ends.

Connection diagrams for neutral wire and grounding

Now you know how to distinguish the neutral wire from the ground and understand that both are connections to the ground. Now you can consider possible schemes for connecting the neutral wire and grounding. All of them are clearly specified in clause 1.7.3 of the PUE. We will consider only schemes with a solidly grounded neutral that are used in our electrical networks.

So:

First of all, let's consider a TT system in which the neutral wire is connected to the grounding of the transformer, and the grounding to an independent source. This method is used very rarely, and the cost of installing such a system is the highest.
Much more commonly used are TN type systems that use PEN conductors. That is, along the entire length or in certain sections, the neutral and protective conductors are laid with one wire, or are connected to one grounding point.

The most optimal in in this case in matters of electrical safety is the TN-S system. In it, the neutral and protective conductors are connected to a single grounding point, but along their entire length they are made of separate conductors.

Much more often you can find the TN-C system, which is quite easy to implement with your own hands. In it, the neutral wire and grounding are made of one wire along the entire length. But this is the least safe option in terms of electrical safety.

And lastly possible option is the TN-C-S system. As the name implies, it combines the two previous systems. That is, in one section the neutral and grounding are laid together, and in the second section they are separated.

Rules for connecting the neutral wire and grounding

Knowing the possible connection diagrams for grounding and the neutral wire, we can talk about the rules and requirements for their connection. After all, although they are not significant, they differ. In addition, we hope that we will explain the frequently asked question of why the neutral wire should be grounded.

First of all, let's talk about the TT system. According to clause 1.7.59 of the PUE this system can only be used in exceptional cases when none of the TN systems can provide the required level of protection.

In the electrical power industry there are not many types of connected wires. There are power wires and protective wires.

In this short article we will not delve into the jungle, three-phase and five-phase networks. Let's look at everything literally on our fingers, on what surrounds us and what is available in all stores and in every electrified home. Simply put, let’s take and open a regular outlet.

Let's start with the times of the past and give preference to the electrical outlet that was manufactured and installed 10, or even 15 years ago. We see that the socket is connected to only two wires.

One of these wires must have a bluish or blue color. This is how it is defined working neutral conductor. There is no current flowing through it from the source - it is directed from you to the source. It is completely harmless, and if you grab it without touching the second one, then nothing terrible or terrible will happen.

But the second wire, the color of which can be any color, with the exception of blue, light blue, yellow-green striped and black, is more insidious and malicious. What do you want, because it is always energized, since it is to it that fresh electrons and charged particles arrive from transformers and generators of power plants and substations. CalledHe phase conductor.

If you touch this wire, you can get a good shock, even fatal. And this is not a joke, since any current whose voltage is over 50 Volts kills a person in a few seconds, and we have at least 220 Volts of alternating current in household outlets.

The presence of voltage on phase conductors can be determined special indicators. They are made in the form of ordinary screwdrivers with a cross or spatula.

The handle of such a screwdriver consists of translucent plastic, inside of which there is a built-in light bulb - a diode. The upper part of the handle is metal.

Touch the working part of the indicator to the conductor, and with your thumb to the metal part on the handle. If the built-in diode lights up, then you should not touch this wire - it is now energized.

Note that the neutral conductor will never cause the diode to burn, since by definition there is no voltage across it, provided that it is not in contact with a conductor carrying current.

But what will we see if we open a modern-made socket that adheres to Euro standards? This socket has three wires. Two are already familiar to us. A phase conductor that is always energized and can have any color. The working neutral conductor usually has a blue or bluish color. And the third conductor, consisting of yellow and green colors along the entire wire, which is commonly called protective neutral conductor. Moreover, usually the phase conductor is located on the right in sockets or on top in switches. And the neutral protective conductor is located on the left in sockets or below in switches.

If voltage flows through the phase wire to the socket, and through the neutral wire it goes from the socket to the source, then why do you need a protective one?

If the equipment connected to the socket is fully operational and the wiring is in proper condition, then the protective neutral conductor does not take any part and is simply inactive.

But let's imagine what happened short circuit, overvoltage or short circuit to parts of equipment that are not normally energized. That is, the current has reached those parts that are usually not under its influence, and therefore are not initially connected to the Phase and Working zero conductors. You will simply feel the electric shock on yourself, and in the worst case, you may die as a result of cardiac muscle arrest.

This is where the same protective neutral conductor is needed. It will take this current and redirect it to the source or to the ground, depending on how the wiring is done in a particular room. And even if you accidentally touch equipment that is not normally energized, you will not feel a strong shock, because current is not a fool either - it looks for easy paths, that is, it chooses the path where there is the least resistance. The resistance of the human body is approximately 1000 ohms, while the resistance of the protective neutral conductor is only about 0.1-0.2 ohms.

Use it modern technologies and standards to be safe at all times under any circumstances. Remember that your safety depends on the actions and measures you take to ensure it!

Yakov Kuzetsov

Purpose

Notes

Sources

“Theoretical foundations of electrical engineering. Electrical circuits» Bessonov L. A. Moscow “Higher School” 1996 ISBN 5-8297-0159-6

Wikimedia Foundation. 2010.

See what “Zero wire” is in other dictionaries:

neutral wire- neutral wire - [Ya.N.Luginsky, M.S.Fezi Zhilinskaya, Yu.S.Kabirov. English-Russian dictionary of electrical engineering and power engineering, Moscow, 1999] Topics electrical engineering, basic concepts Synonyms neutral wire EN inner mainneutral main ...

neutral wire- 3.35 neutral wire (symbol N): A wire connected to the neutral (zero) point of the network and capable of transmitting electricity (IEC 826 01 03) (ISO/TR 12100 1, 3.22 as amended). Source: GOST R IEC 60204.1 99: Safety... ...

neutral wire (N)- 3.57 neutral wire (N): A wire connected to the neutral (zero) point of the network and capable of transmitting electrical energy (see). (See 3.35 EN 60204 1.) Source: GOST EN 1070 2003: Equipment safety. Terms and... ... Dictionary-reference book of terms of normative and technical documentation

neutral wire- rus neutral conductor (m), neutral conductor (m) eng neutral conductor fra conducteur (m) neutre, neutre (m) deu Neutralleiter (m), Nulleiter (m) spa conductor (m) neutro, neutro (m) ... Occupational safety and health. Translation into English, French, German, Spanish

neutral wire- nulinis laidas statusas T sritis automatika atitikmenys: engl. neutral conductor; neutral wire vok. Nulleither, m rus. neutral wire, m pranc. conducteur neutral, m; fil neutral, m; ligne neutre, f … Automatikos terminų žodynas

neutral wire (symbol N)- A wire connected to the neutral (zero) point of the network and capable of transmitting electricity. [GOST R IEC 60204 1 2007] Topics: electrical safety... Technical Translator's Guide

Wire connected to common point connections of the ends of phase windings of machines and transformers. Technical railway dictionary. M.: State Transport Railway Publishing House. N. N. Vasiliev, O. N. Isaakyan, N. O. Roginsky, Ya.... ... Technical railway dictionary

neutral wire (symbol N)- 3.37. neutral wire (symbol N): A wire connected to the neutral (zero) point of the network and capable of transmitting electricity. [MES 826 14 07, modified]