Wiring in an apartment is a job that not all home masters risk doing on their own, trying to shift it onto the shoulders of professionals. However, there are tasks for which it will be at least embarrassing to call a specialist - no skills are required to complete them. These include the search for phase and zero in the outlet and its subsequent installation. For masters with even little experience, such work does not present any problems, it is elementary. But for those who first faced this challenge, today's article will be very useful or at least interesting.
Why do I need to know the location of the phase and neutral wires?
There are people who do not even know such concepts, but any self-respecting home master should understand the differences between these terms. The determination of the phase, neutral and ground conductor is necessary for the correct installation of outlets. If we are talking about a junction box, then the task is even more important. It is not possible to make wiring to the switch without such a check. After all, if you send the same wires to the disconnector as to the outlet (phase / zero), then the only thing the master will achieve is a short circuit.
There are several ways to determine: from all familiar to truly exotic. Just looking at the connection point to understand where the phase and zero will not work in the outlet - GOST does not provide for their specific location (right or left). So, you should deal with this issue more carefully. But first, a little theory.
Where do 220 V from the outlet come from?
To the nearest transformer substation from the house comes 6 kV via three phase wires. It is on it that the voltage drops to 0.4 kV, familiar to everyone, distributed over power shields. Zero appears as follows. All 3 transformer windings at the substation are connected โto a starโ. With a similar switching in the center, where the ends of the coils are in contact, a working zero is formed. After it is connected to the substation circuit, a grounded neutral is obtained, which goes along with three phases (380 V) to houses and apartments.
The question may arise: if 380 V (4 wires) has arrived, why does the phase and zero form 220 V in the outlet? Everything is simple here: 380 V is the voltage between two wires, called phase. If you take zero instead of one of them, you get a linear 220 V. Only in this case, household appliances can work.
What are the wires coming into the apartment?
If we talk about schemes, then the marking is as follows:
- L is the phase.
- N is zero.
- PE - grounding.
The cores themselves are color-coded - yellow-green (earth), blue or cyan (zero), any other color (phase). Electricians even with little experience know that its observance is mandatory. Indeed, in addition to the convenience of installing and maintaining networks in the future, this can save someone's life. Designations of phase and zero on sockets are most often, alas, not.
Methods for determining phase and zero contact on outlets
There are several methods to help resolve this issue. The simplest (if the outlet is removed or pulled out of the glass) is color coding. However, no electrician will blindly trust her. Indeed, even if the master is sure that a professional worked before him, the color marking is for informational purposes only. For your own confidence, you should double-check where the phase and zero are in the outlet, independently. So, you need to use special equipment, which may include:
- indicator screwdriver on neon or LED;
- multimeter;
- warning lamp.
Search for phase and neutral wires by indicator
Such a screwdriver is convenient for work, even if a person first encountered a similar problem. To check, you should touch her sting to the contact, putting your finger on the metal platform at the back. Nothing will happen on the neutral conductor, as well as on the ground. But when in contact with the phase, the neon light in the body will light up.
If such a device is used with LEDs, then touching the platform is not necessary. Such indicator screwdrivers are equipped with batteries and the LED lights up itself. However, their problem is high sensitivity to guidance currents. This method is good for determining the phase and zero in the outlet, but is not able to help find the ground wire if only 3 wires stick out at the point of connection.
Using the warning light to search
This method is a bit more complicated. To use it, you need a light bulb and a cartridge with wires. A small digression: if the apartment is not grounded, beginners should not use this method - it is quite difficult.
By connecting one of the wires of the cartridge with the contact, you need to touch in turn the two others. After the main contact changes and the actions are repeated. You need to do the same for the third time. In the end, you need to find a wire that will light the lamp regardless of the second contact. This will be the phase. But with a two-wire system, without grounding, you have to work hard.
One of the cores of the control lamp needs to be extended so that it reaches the heating battery or water supply pipe. Voltage is checked between it and one of the contacts. The presence or absence of a glow will indicate phase and zero in the outlet, respectively.
The most reliable option is to use a multimeter
The switch of the device must be set to the position of alternating voltage to any position above 250V. After that, the black probe should be clamped with your fingers, and the red one should touch each of the contacts in turn. Changing the display or deflecting the arrow will indicate a phase conductor. Now you need to understand how to determine the phase, zero and grounding in the outlet.
The voltage between the pairs is measured. One of the tested indicators must be a phase. A lower voltage indicator, even slightly, will indicate grounding. If the numbers on the display are completely identical, then protective zeroing has been performed (the neutral is connected to the ground). But whether everything is done correctly is another question.
In order to make the algorithm of actions more understandable, a video on this topic is presented below.
More exotic way to search
An interesting option is the definition (where phase, where zero in the outlet), without additional equipment. To work, you only need a wire, a resistor (1 Mฮฉ) and ... ordinary raw potatoes. Perplexity and distrust now appeared in the eyes of some, but this is indeed a working method.
One of the wires is connected to a water pipe or heating. Its second end is stuck in a slice of potato. A separate core is connected to a resistor. She also sticks into the tuber, at a distance of 0.5 cm from the first wire. Now the rest of the contacts are checked in turn, delaying for every 1-2 minutes. The phase wire will give itself out as a reaction - the starch on the cut will begin to foam.
Very important! If the home master does not have experience in such work, it is better to forget about a similar method. Its use is a complete violation of the rules of electrical safety.
How to connect the socket (phase, zero, ground)?
Having decided on the purpose of the conductors, you can proceed with the installation of the power point itself (if it is missing). On the back of the outlet there are two contacts at the edges and one in the middle. To the right and left, the phase and neutral wires are connected. Their location does not matter, however, if the home master independently decided to install all the points in the apartment, it is better to create a certain system for yourself. This will help later and save you from new searches. For example, you can connect all sockets according to the scheme: zero on the right, phase on the left.
The central contact is designed to connect the grounding conductor - it is connected to the bracket, which is clearly visible on the front side of the outlet. If the third (yellow-green) vein is absent, it remains empty. Many "craftsmen" advise putting a jumper on the ground bracket from the zero contact. In no case can this be done - when a breakdown of the insulation of the phase conductor on the housing of the household appliance occurs, a short circuit will occur, which will lead to equipment failure. And if at the same time the zero is weak, its burning is possible. Then, in contact with the device, even death is possible.
Conclusion
Determining the phase and zero in the outlet is a simple process. And even more so for this you should not call for the help of a specialist, pay for his work. Itโs easier to do it yourself. However, if the work is done without removing the panel, you should be careful and accurate. It must be remembered that electric shock is hazardous to life and health.