What wire is allowed on the switch: zero or phase?

Whether you are a specialist or not, and if you decide to change the electrical wiring in your house, even if you need to know the elementary rules of the electrical installation code for the box-circuit-breaker-light section (full interpretation - “Electrical Installation Rules”, that is, a set of standards applicable to any electrical installations and power grids). It is from here that you can get information about whether the switch goes to zero or phase.

What wire is the light switch powered by?

Colors lived in cable

Despite the fact that in some apartments you may find that “zero” comes to the switch, this is by no means normal. Because any switch must break the phase. If the zero or phase on the switch are mixed up, most likely, some woe-craftsman had already “digged” in the wiring of this apartment or the zero wire was originally powered not according to the standard.

What colors should be in the wires in the electrical wiring of the apartment

Any conductor purchased for wiring must contain a core with a blue (blue) braid. It is her that is recommended to be used on the network as a neutral wire. If the apartment has a third wire - direct grounding, it is recommended to let a yellow-green wire onto it. All other wires (this can be white, brown, black, etc.) are used as phase carriers. So to the question whether the switch breaks the phase or zero, the answer will be unequivocal - the phase, and this wire will not be blue (blue) and not green.

Three-core cable for an apartment with grounding

If the wires in your apartment are mixed up, it means that the installation of the wiring in it was not done by professionals and, most likely, it has already undergone repairs.

The essence of electricity

Let's try to explain the work of electricity in the most accessible words. We also know from physics lessons that the very essence of electricity is such that the phase always tends to discharge to zero. It is between the carrier of electric energy and the grounding stream that various devices are connected to the circuit. Then the discharge occurs in them, forcing them to work.

In particular, the filament or diode circuit in the lighting lamp also works this way. A filament or a diode circuit has its own resistance, which is balanced so that the lamps, when the network closes through them, do not burn out, but begin to glow. And in fact, it does not matter which wire is suitable for the switch - zero or phase, if zero is supplied to the lamp from one contact and a phase is supplied from the other, it will work anyway. This will not affect the performance of the device. This is for security purposes only.

Why is the “phase" and not the "zero"?

We got close to the answer to the question of whether zero or phase goes to the switch and why. The switch opens the network section in which the light bulb operates. And he interrupts in simple switches only one of the wires that passes through it. The second wire remains directly connected to the lamp. If in your case a zero is passed through the switch, then a phase is connected directly to the chandelier, which means that even with a simple light bulb replacement, the device can shock you.

If the switch opens the phase, then directly to the chandelier from the box goes zero. This means that if the switch is in the open (off) state, the phase is no longer supplied to the device, since it is interrupted by the switch itself, and replacing the lamp will be safe.

Correct installation of the switch with the replacement of the wires going to it and to the chandelier

Simple switch connection

When we figured out the question of which wire - “phase” or “zero” should come to the switch in order to comply with the rules of the electrical code, we will figure out how the correct circuit of the home power section will look, which will determine the normal operation of the appliance. Again, we will explain everything in simple words (for safety reasons, all work associated with the installation or repair of electrical wiring should be carried out with the central machine turned off in the main panel).

  1. For the correct installation of wiring from the nearest junction box, we must have done two gates - one to the switch, one to the chandelier.
  2. How to connect a phase-zero switch, that is, a conventional switch? Take a piece of two-wire wire. We pass it through the side opening of the box, going on a strob to the switch. We also pass the cable through the side opening of the switch box.
  3. We feed one core to the left terminal of the switch, the other to the right. In the box, one of the cores is fed to the phase wire. One remains free so far.
  4. What did we do? Now the current comes to the switch and in the closed position of the switch returns to the box. It remains to mount the network for the lighting device.
  5. Suppose we have a chandelier designed for one lamp. Then a normal two-wire cable will do. We pass it through the side opening of the box leading to the chandelier, close it up in the stroba and connect it to the terminals of the chandelier.
  6. In the box, we connect the two-core cable that goes to the chandelier as follows: we feed one core to the returning free core, the phase from the switch, and feed the other to the main zero in the box.
Chandelier works

The circuit is assembled. Now, knowing which wire goes to the switch, “zero” or “phase”, you have made a network section that ensures the operation of the lighting device is completely safe.

In conclusion, some nuances

In our article, we focused on a simple network that does not provide for a third wire - grounding. We also started from the fact that we have a simple chandelier, designed for 1 cartridge for a lamp. Therefore, the switch we have is simple - single-key.

In the case of grounding, you will never confuse. You just have to use a three or more core cable and always feed the yellow-green core to the ground, that is, to the terminal that goes to the device body.

Three-key switch

And in the case of multi-key switches, you will have to throw two or more (depending on how many keys are in the switch) from the box onto the switch. The same should be done with washing the chandelier. No matter how much the phase comes from the switch, the zero in it will always be one, its terminal will be highlighted separately. You can also navigate and wire. Zero in devices will always be blue (blue).

Source: https://habr.com/ru/post/A13640/

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