How to determine the phase and zero with indicator screwdrivers of various modifications

Every electrician knows how to determine the phase and zero with an indicator screwdriver, but it is not always possible to invite a specialist if there is no electricity in the house. In this case, the initial diagnostics can be carried out independently, because the phase probe is a very simple device that does not require special knowledge for its use.

How an indicator screwdriver works

To understand how to use an indicator screwdriver, one must at least in general terms imagine its structure.

The simplest device consists of the following components:

• Screwdriver tip. The part of a device that touches wires or contacts that need to be checked for voltage.
• Resistor. It is a conductive part that allows electric current to pass through, but reduces its value. The resistance of the resistor is selected for a specific voltage for which the indicator screwdriver is designed. If the device is designed to indicate a voltage of 220 volts, then you should not climb into a high-voltage transformer with it.
• Indicator. The electric current is not visible to the eye, so its presence or absence can be judged solely by indirect signs, one of which is the glow of a light bulb.
• Spring. Is a conductor between the indicator light and the contact plate. At the same time, it clamps the light bulb inside the device body.
• Contact plate. It holds all the parts inside the device, at the same time being a contact, after touching which, an electrical circuit is closed that feeds the indicator light.
• Insulation. A 220 volt current flows along the tip of the indicator screwdriver, if it is present in the tested network. To avoid electrical shock, the body of the device and its sting are covered with a dielectric for almost the entire length. Often it is transparent plastic of a yellowish tint, through which the device of the indicator screwdriver is clearly visible.

An ordinary indicator screwdriver is a disposable device - if it breaks, then the used device can only be thrown away.

The principle of operation of the simplest, passive indicator screwdriver

To make sure that there is or is no voltage in the electrical network, you need to observe the lamp of the indicator screwdriver, and touch the current-carrying contacts of the socket with its sting. In this case, one of the fingers of the hand must touch the contact plate.

In order for the lamp to light up, a phrase must be brought to one of its contacts, and zero to the other. If there is a phase voltage at the contact of the socket, then it goes through a resistor to the light bulb connector. The human body plays the role of a neutral wire, since it has sufficient electrical capacity and resistance. When a phase comes to one end of the lamp, and the finger touches the contact plate, the circuit is closed and the lamp starts to glow. Thus, by touching the plug of a screwdriver to the contacts of the socket, you can find the phase and zero.

The disadvantage of such a device is the presence of a resistor, and the weak point is the indicator lamp. The first does not allow detecting the presence of voltage less than 60 Volts, and the lamp may burn out if, for some reason, the voltage in the network is higher than the nominal. Phase breakdown to ground is also likely - everything is turned on, and the sockets do not work (if grounding is done correctly).However, such cases are very rare exceptions to the general rule, and basically the indicator screwdriver does its job well.

How more sophisticated, active indicator screwdrivers work

The simplest indicator screwdrivers use the contact measurement method, that is, in order to determine the presence of voltage, it is imperative to touch the sting to the conductor. This is quite convenient, but it does not solve most of the problems that electricians face when searching for faults in electrical networks.

operating instructions for the indicator screwdriver (click to enlarge)

A more advanced model of indicator screwdrivers can work in a contactless way - they react to an electromagnetic field that occurs in any conductor when an electric current flows through it. The device of such cards is much more complicated - they already have their own scheme and separate power supply. Most are equipped with sound indication. A separate category includes indicator screwdrivers with an LCD screen - such models can even show what voltage is in the measured network.

The principle of operation is very simple - the screwdriver has a coil and when it enters the field around the conductor, an electric current appears in it, which makes the indicator lamp glow and the buzzer sounds. This property of non-contact indicator screwdrivers allows you to find breaks in the wiring even through the wall - without such a device, you would have to completely remove the wallpaper and knock down the plaster wherever the wire is laid.

Before using a screwdriver with an indicator with the possibility of contactless detection of the presence of voltage, one must not forget to turn on their power - so that the battery does not sit down, they have a switch.

How to use how to use such an indicator screwdriver, you can find out by watching this short video instruction:

In addition to indicator screwdrivers, there are other types of voltage detectors, which you can learn about by reading this article.

What the indicator screwdriver can show

Determination of any faults in the electrical network with a voltage indicator only makes sense if there is no light in the apartment, but there is definitely electricity in others along the entrance. The same applies to private houses - the first step is to find out if the neighbors have electricity.

If the problem is still in your apartment, then most often the indicator screwdriver shows two diametrically opposite results:

• There is no phase in any of the socket contacts. There can be many reasons for this, and most of them require professional intervention. On your own, you can only determine whether the plug has burned out (more often an "automatic" device is installed instead of it - an automatic shutdown device, when the nominal values ​​of the current in the circuit are exceeded). To do this, you need to find plugs near the counter and check with a tester whether there is voltage on the contacts before and after it. If the plug is burnt out, then it must be replaced, and if there is a machine gun, then it could be knocked out - it has a lever that is turned up in the working position (if the device is installed correctly).
• There is a phase on all contacts of the sockets. With almost one hundred percent guarantee, this means that the neutral wire near the meter has burnt out. If you do not have the skill of electrical work, then an electrician must be invited to solve the problem.

Nuances of using an indicator screwdriver

To understand how to use the indicator screwdriver correctly, you must always remember about the shortcomings of this device:

1. The first and most important rule is that always and everywhere, before finding the phase and zero, it is necessary to check the operability of the device. It is clear that if the indicator screwdriver is faulty, then in the best case the fault will simply be incorrectly identified, and in the worst case you can get an electric shock.
2. The probe indicates the presence or absence of voltage on a specific surface of the conductor.If there is no current at the socket connectors, this does not mean that it is not in the wire that fits to it - the contact or the wire itself could burn out. Therefore, all sections of the chain must be checked.
3. The indication also occurs when there is less voltage than it should be in the network. This means that if the contact near the meter is partially burnt and still passes 50-100 volts, then the indicator screwdriver will show the presence of voltage, and electrical appliances will not work.
4. Under certain circumstances, a screwdriver can react to so-called pickup currents, showing the presence of voltage where there is none.
5. If the phase tester shows that there is now no voltage in the network, this does not mean that it cannot appear there in the next few minutes. If you need to disassemble the outlet, then without fail before this you must turn off the input machine or unscrew the plugs.

Another video, a 6-minute video with a story about the use of various types of indicator screwdrivers:

As a result, it is very simple to use an indicator screwdriver, but one must remember that its readings are only half of the "diagnosis" - if there is no clear understanding of why it shows the presence or absence of voltage, then it is better to contact an electrician. It should also be borne in mind that despite the name, the indicator screwdriver is not designed for loosening bolts, therefore it has the appropriate strength.