What letter and color indicate zero and phase in electrics

When self-connecting electrical equipment - lamps, ventilation, automatic machine, users can find the letter designations of the terminals. L, N in electrics is the phase and ground to which the corresponding cables are led.

Wire lettering

Wire Alphanumeric and Color Coding Standards

For household and industrial power lines, insulated wires with internal conductive cores are used. Products differ depending on the color of the insulation coating and markings. Phase and zero designation in electrics speeds up repair and installation work.

Marking of cables in electrical installations under voltage up to 1000 V is regulated by GOST R 50462-2009:

  • in clause 6. 2.1 it is indicated that the neutral conductor is marked as N;
  • See paragraph 6.2.2. states that the protective conductor with earth is designated PE;
  • in section 6.2.12 it is said that in electrics L is a phase.

Understanding the markings simplifies installation work in commercial, residential and administrative buildings.

L - phase designation

L and N notation in electrics

There is a phase conductor under voltage in the AC network. Translated from English, the word Line means an active conductor, a line, therefore it is marked with the letter L. Phase conductors are necessarily covered with colored insulation, since, being in a bare state, they can cause burns, human injuries, fire or failure of various equipment.

N - alphabetic character zero

The sign of a zero or neutral work cable is N, from an abbreviation for the terms neutral or Null. When drawing up a diagram, the terminals for switching zero in a single-phase or three-phase network are marked in this way.

The word "zero" is used only on the territory of the CIS countries, the whole world is called neutral.

PE - earthing index

Grounding marking

If the wiring is grounded, the letter marker PE is used. From English, the meaning of Protective Earthing is translated as ground wire. Clips and contacts for commutation with grounding zero will be similarly designated.

Coloring the insulation coating of conductors

It is necessary to color the grounding, phase and zero cables in accordance with the requirements of the PUE. The document establishes differences in colors for grounding in the switchboard, as well as for zero and phase. Understanding the color coding of the insulation eliminates the need to decipher the letter markers.

Ground conductor color

On the territory of the Russian Federation, since January 1, 2011, the European standard IEC 60446: 2007 has been in effect. It notes that grounding has only yellow-green insulation. If an electrical circuit is drawn up, the ground should be designated as PE.

There is a grounding conductor only in cables from 3 conductors.

PEN conductors used in old buildings combine ground and zero conductors. The insulating coating in this case has a blue grounding color and yellow-green cambric at the connection points and the ends of the wire. In some cases, reverse marking was used - green-yellow grounding with blue tips.

The earth and zero conductors of PEN cables are thinner than phase conductors.

The organization of protective grounding is a prerequisite for creating an electrical network in residential and industrial buildings. Its need is indicated in the PUE and GOST 18714-81. The standards state that neutral ground should have the lowest resistance. In order not to get confused, use the color marking of the cables.

Color coding of zero working contacts

Wire color in wiring

In order not to confuse where is the phase, and where is zero, instead of the letters L and N, they are guided by the colors of the cables. Electrical standards state that neutral is blue, cyan, blue-white, regardless of the number of conductors.

Zero can be denoted by the Latin letter N, which is read as a minus in the diagram. The reason for reading is the participation of zero in the closure of the electrical circuit.

Phase wire colors

A phase is a live line that, if touched inadvertently, can lead to electric shock. Newbie craftsmen often have difficulty finding a cable. The phase is indicated by black, brown, cream, red, orange, pink, purple, gray and white.

The phase letter is L. It is used where wires are not color coded. When connecting the cable to several phases, next to the letter L, a serial number or the Latin letters A, B, C are put. The phase is also often marked as a plus.

The phase wire cannot be blue, light blue, green or yellow.

Why use color coding

You can determine L and N in an electrician using an indicator screwdriver. You will need to touch the tip to the part of the product without insulation. The glow of the indicator indicates the presence of a phase. If the LED did not light up, the zero lived.

Color coding reduces the time to find the right wire, troubleshoot. Knowing the colors of the conductors also eliminates the risk of electric shock.

Nuances of manual color marking

Wire color coding with cambric

Manual marking is used when using wires of the same color in old buildings. Before starting work, a diagram is drawn up with the color values ​​of the conductors. During installation, you can mark current-carrying conductors:

  • standard cambric;
  • cambric with heat shrinkage;
  • insulating tape.

The rules allow the use of special kits for marking. The points of installation of markers to indicate zero and phase are indicated in the PUE and GOST. These are the ends of the wire and where it connects to the bus.

The specifics of marking a two-wire wire

Heat shrinkable tubing for wires

If the cable is already connected to the network, you can use an indicator screwdriver. The difficulty of using the tool lies in the impossibility of determining several phases. You will need to call them with a multimeter. To prevent confusion, you can color-code the electrical conductor:

  • select tubes with heat shrinkage or electrical tape to indicate zero and phase;
  • work with conductors not along the entire length, but only at the joints and joints.


The number of colors is determined by the scheme. The main thing when creating it is not to get confused, not to use yellow, green or blue markers for the phase. It is allowed to mark it in red or orange.

Marking a three-core wire

Using a multimeter, you can determine the location of the phase, zero, and ground

To search for phase, ground and zero in a three-wire wire, it is advisable to use a multimeter. It is put on the alternating voltage mode and gently touch the phase with the probes, then the remaining veins. The tester's values ​​should be recorded and compared. In a phase-to-earth combination, the voltage will be lower than in a phase-to-zero combination.

After specifying the lines, you can make markings. To understand if the phase is L or N, the corresponding color will help. At zero, it will be blue or blue, at plus - any other.

5-wire system marking procedure

Wiring from a three-phase network is carried out only with a five-core cable.Three conductors will be phase, one will be neutral, and one will be protective ground. Color coding is applied in accordance with regulatory requirements. For protection, a yellow-green braid is used, for zero - blue or light blue, for a phase - from the list of permitted shades.

How to mark aligned wires

Two or four conductor cables are used to simplify the wiring process. The line of defense connects here with neutral. The letter code of the wire is PEN, where PE stands for grounding and N stands for neutral conductor.

According to GOST, special color coding is used. The length of the aligned cable will be yellow-green, and the ends and connection points will be blue.

Highlight the main points of problem areas with cambric or electrical tape.

Coloring wiring as a way to speed up installation

Correct color of the wiring speeds up the installation of wiring

Before the start of GOST R 50462-2009, cables were marked in white or black. Determination of the phase and zero was carried out during the disconnection by the control at the moment of power supply.

The use of color markers simplifies repair work, ensures their safety and convenience. Guided by the shade of the cables, the master will not spend a lot of time to conduct electricity to the house or apartment.

You can consider the meaning of color coding using the example of a luminaire. If the lamp changes, and zero and phase are reversed, there is a risk of injury or death from electric shock. When in electrics the designation L and N is made in color, the phase will go to the switch, and zero - to the light source. The voltage is neutralized, and it will be possible to touch even the included light bulb.

Requirements for the color of the wiring during installation

Switching off the switch box

A copper wire with one or two cores is pulled from the switch box to the switch. The number of cores depends on the number of keys on the device. The phase should break, not zero. In the process of work, it is allowed to use a white conductor for powering, making a note on the diagram.

The socket is connected with the correct polarity. The working zero will be on the left, the phase will be on the right side. The ground is located in the middle of the device and is clamped with a terminal.

If there are two cables of the same color, you can find the phase and neutral using a test, an indicator screwdriver, a multimeter.

On the wiring diagram, it is worth indicating what L and N mean, but several of them are used in electrics. The single-line shows the power section - the type of power supply, the number of phases per consumer. Here it is advisable to draw one notch on a single-phase network, three on a three-phase network and indicate the wires in color. Switching and protective equipment is marked with special symbols.

Correct marking and color marking of wires ensures the quality of line installation and maintenance. Marking in accordance with international requirements allows electricians and DIYers to navigate the diagram.

ihome-en.techexpertolux.com
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  1. Sergey

    Thank you

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