Individual wires-cores that make up electrical cables are insulated in certain colors. The color of the insulation is regulated by GOST R 50462-2009, this document contains the features of n and l markings in electrics in order to simplify the work of foremen at large facilities and ensure safety during the repair process. Those who decide to repair electrical appliances on their own or other similar work should also know what color the ground, phase and zero wires are.
Features of the colors of the veins
To avoid errors, the requirements of the PUE describe the colors of all main electrical wires. If an experienced electrician was involved in the commissioning work, following the rules of the PUE and the corresponding GOSTs, during self-repair, you will not need an indicator screwdriver or other devices that determine the purpose of a particular core.
Color coding in electrics according to GOST
Earthing
The green-yellow wire is the ground. In schematic diagrams, the neutral conductors are marked with the letters PE. In some houses of old buildings, there are PEN wires in which the grounding is combined with a zero conductor. If the cable was stretched according to the rules, wires with blue insulation were chosen, and only the ends and places of twists were yellow-green (they were put on thermotubes). The thickness of the "zero" and grounding can be different. Often, the thickness of these two conductors is less than the thickness of the phase conductor, this occurs when connecting portable devices.
If we are talking about laying electrical wiring in multi-storey buildings and in industrial premises, the rules of the PUE and GOST 18714-81 come into force, prescribing the mandatory arrangement of protective grounding. Grounding must be of minimal resistance in order to compensate for the effects of line faults and to prevent harm to human health. That is, compliance with the standards for color coding of PUE wires is of paramount importance.
"Zero"
What color is the neutral wire? Electrical standards dictate that its insulation can be blue, blue with a white stripe, or cyan. This marking will be present on cables with any number of cores. In schematic diagrams, "zero" is marked with the letter N, a circuit is closed to it. Sometimes it is called "minus", and phase - "plus".
"Phase"
The color of the phase is of paramount importance to the electrician: handling conductors requires care and knowledge. The slightest touch of the phase can lead to injury. Phase wires marked with the letter L have a lot of colors in the wiring, the prohibition applies only to the use of blue, yellow and green colors. If the cable is three-phase, the serial number of the core is added to the letter L.
When a single-phase circuit is separated from a three-phase circuit, electricians use cables with exactly the same color, watching the color of the phase and zero in the wire. Before starting work, they determine for themselves how the different veins will be connected, and then follow the chosen color. Sometimes thermocambric is fused on them or several turns of the corresponding colored tape are wound.
According to GOST:
- phase wires of black color, are used in power circuits operating with direct and alternating current;
- red - used in control circuits rated for alternating current;
- with orange color - meet with interlock control circuits powered from external sources.
How to determine the purpose of the wire - neutral or ground?
L N marking in electrics is not always observed in old buildings, therefore, the question arises of independently distinguishing between the neutral wire and the grounding wire. When the circuit is closed, an electric current passes through "zero". The grounding wire has only a protective function, and in the "normal" mode, the current does not flow through it.
You can find out whether it is "zero" or "ground" like this:
- Use an ohmmeter, having previously disconnected the voltage between the measurement points. The resistance on the ground wire will not exceed 4 ohms.
- Use a voltmeter and sequentially measure the voltage between the "phase" and other wires (the method is suitable for three-core cables). The ground wire will give the greatest value.
- If the colors of the "phase", "zero" and "ground" wires are unknown, and you need to find out the voltage between the ground wire and some obviously grounded object (for example, a heating radiator), a voltmeter will also come in handy. True, when connecting "earth" and a grounded object, it will not show anything. But a small voltage will be reflected on its indicator, if you do the same with the "zero" wire.
In a two-core cable, only the phase and neutral wire will always be present.
What to do if all conductors in the cable are insulated with the same color
The question of marking wires by color does not make sense when you have to work with single-color conductors - for example, when fixing wiring in old houses. For such cases, there are kits that make it possible to mark the conductors. Areas for fixing marking devices are prescribed by the requirements of GOST, usually they are fixed near the point of connection to the bus.
How to mark a wire with two conductors
If all the wires in the cable have the same insulation, and the electrical appliance is already connected to the network, the craftsmen use indicator screwdrivers. The latter glow when the metal part touches the phase wire. To mark a two-core cable, in addition to such a screwdriver, you will need thermocambric or multi-colored electrical tape. Colors will be indicated only at the joints - it is not necessary to wrap the core with colored tubes or electrical tape along the entire length.
Probe screwdriver indicator
Phase wires can be marked in any color other than blue, yellow, and green. If a two-core cable is connected to a single-phase network, it is customary to mark the phase wire in red.
How to mark a 3-core wire
What is the color of the ground wire in a three-wire wire? If the answer to the question is not immediately determined, all the insulation on the veins is of the same color, a multimeter will help out. The device is set to alternating current, and the master sequentially touches with both probes, first the phase wire, then the rest of the wires, memorizing the indicators. Touching phase and zero will give more voltage than touching phase and ground.
What color is the ground wire? It has a yellow-green color. It is such a thermocambric or electrical tape that should be used to mark "ground" in a three-core cable. On "zero" - you should wind a blue tape, on the phase - not blue and not yellow-green thermocambric.
Letter designation of phase, zero and ground
The use of different colors of wires in electrical wiring is a convenient and logical measure that simplifies repair and installation work. If wires with multi-colored cores are laid in the house, during the repair you will not have to waste time on "ringing" each of them, and, for example, a break in a phase core will be detected quickly. The presence of phase and zero also matters, but working with letters and numbers is still more time-consuming than with color: just look at the cable - and the purpose of the cores immediately becomes clear.