Working with existing electrical installations and cable and wire products carries a risk of electrical injury. The reason for this is banal - the directed movement of charged particles along the conductor cannot be seen with the naked eye. Therefore, during installation, routine maintenance and repair of electrical equipment, a tester must be used to check the voltage
able to at least simply show the presence of potential, even without measuring its effective value.
A vital necessity
A voltage tester is a portable electrical device designed to indicate the presence of potential in conductive areas. In electrical networks, not all wires are dangerous when touched. Those with a phase are beating current, but a neutral or earth wire is safe. True, there are reservations.
To understand what a voltage tester may be needed at home, it is easiest to give a number of examples. Imagine that there was a need for a grinder (grinder), which was temporarily provided by a neighbor. Still used models, the body of which is made of metal. How to check that the internal circuits are intact and there is no voltage on the shell? Working with such a tool without first checking it is a very risky undertaking. Or, for example, you need to change a blown bulb in the lamp, the glass bulb of which fell, and only the base remains in the cartridge. Believe the electricians who performed the wiring that the switch really breaks the phase wire, and not the zero wire, and boldly unscrew the base? Doubtful! There are a lot of similar examples. Having your own voltage tester, you can always quickly check the area of the electrical installation. In addition, more sophisticated models allow you to measure the actual value.
Basic features
To check the fact of the presence of potential (phase), there is no need to spend money on the purchase of an expensive device.
The simplest voltage tester is an indicator screwdriver. Inside its transparent case there is a small bulb that lights up when the sting touches the area under potential.
How to check the voltage with a tester? On the upper side of the dielectric handle there is a special metal nickel. To check the section of the circuit, it is necessary to touch the tip of the screwdriver to the tested conductor, and with your finger to the "five-copeck" pen. The sting itself must not be touched. If a phase is present, the light inside the screwdriver will light up. The second name for such screwdrivers is probes. They are designed for voltages up to 250 V.
It is not recommended to buy the cheapest models, since in case of breakdown of the internal resistor or an error in the circuit, an electric shock can be obtained . More advanced solutions do not require a direct touch on a section of the chain. The sting of such a screwdriver just needs to be held over the conductor. Designed for voltages up to 600 V.
In addition, some models are equipped with a display that displays the actual value.
There are modifications that do not require a finger to touch the "five-copeck". You can purchase a voltage tester without any problems. The instructions to it must be read. This will not only save the device from damage, but also protect the person himself.
Dual screwdriver
At the same time, the tool described above is too narrowly specialized. If it is required, for example, to perform the simplest task - phasing, then it turns out to be useless due to the presence of only one pole. In this case, you should pay attention to a more advanced tester - a dual low voltage indicator. Structurally, it can be compared with two screwdrivers connected by a wire. The maximum permissible voltage is 1 kV. Cost - from 100 rubles.
Consider how to measure voltage with a tester of this class. A sting electrode of one part needs to touch the checked section of the circuit, and the other - to the "ground". It can be any grounded conductor, since the dangerous potential does not flow through the device.
If the light inside the case lights up, it will mean that there is voltage in the area. If you need to perform phasing, you need to touch one probe to one phase wire, and the other to another. If the phase on the wires is of the same name, then there will be no indication. Simpler models show the fact of the presence of the phase, while complicated ones contain several LEDs on one of the handles, by which they can be used to determine the voltage value.
Indicator
The next class of such devices are voltage indicators. The most famous models of the Ukrainian manufacturer "Contact". Their cost starts from 400 rubles. Structurally, such testers remotely resemble twin screwdrivers, but they have more advanced features.
In particular, with their help it is possible to determine the presence of a phase, approximately estimate the voltage level by the glow of the LEDs, and check the conductor for integrity. A capacitor is located inside, which must be pre-charged by touching the probes to 220 / 380V for 20-30 s.
How to find a phase wire
Consider how to check the voltage with a tester. One of the probes of the device needs to touch the checked area of the electrical installation, and with your finger - to the Ph electrode on the housing. If the corresponding LED lights up, then this conductor is energized. True, there is one nuance that is very well known to people who know how to work with a voltage tester of this type. It lies in the fact that the phase check through Ph is not always correct, since indications can be influenced by interference from nearby conductors with current. Let us explain: there are two adjacent wires located, one of which is energized, and the other is de-energized. If you do not know how to operate the voltage tester in detail, then when checking both conductors by touching them and the Ph electrode, it turns out that according to the indication they are both phase.
However, it is not. Just in a de-energized induced EMF under the influence of an
electromagnetic field. It reaches only a few tens of volts, but is determined by the device and is not a malfunction in its operation. In such cases, if in doubt, you need to do otherwise: touch with one probe to the area to be checked, and with the other - to a deliberately grounded point. If there is a phase on the conductor, the LEDs will light up and show an approximate value of 220 V. By the way, having access to a three-phase voltage, you can check the area by touching not only the ground, but also other phase wires. That is, the actions are similar to phasing. If voltage is present in the area, touching the opposite phase will cause the LEDs to glow at 380 V.
Feature of working with a tester-pointer
The specification says that the current flowing through the circuit of the device when checking the potential of 220 V is not more than 10 mA. That is, if you touch one of the probes to a portion of the electrical installation that is energized, then the ammeter connected to the other probe will show the above current value.
Theoretically, this is a dangerous value (100 mA - deadly), in practice, hand touch is possible, but as long as the internal circuits of the device are working.
Preparing to work with "Contact"
All decisions in which two blocks are interconnected by a wire are potentially dangerous. One of their drawbacks is the possibility of damage to the connecting conductive core with the visible integrity of the sheath. Therefore, when checking the presence of a phase through Ph, it is recommended to use the probe of the block on which this electrode is placed. In this case, the LED will work even if the wire is damaged. Nevertheless, before taking measurements, you need to connect the device to the network and hold it for 20 seconds - during this time the internal energy source will be charged. After this, you need to connect the probes together. If the wire is whole, the “test” LED will light up.
Universal tool
In addition to all of the listed devices, there is another variety - multimeters. Perhaps this is the most advanced voltage tester. How to use it, we will now tell. The cost of the most affordable models starts from 300 rubles. The procedure is described in the accompanying instructions, which you need to familiarize yourself with. If we talk about checking the voltage, then one wire must be connected to the COM connector, the other to V. Then set the switch to AC 750 mode (alternating current type, 750 V limit) and touch the probes to the ground and the tested section.
conclusions
Thus, it is impossible to give an unambiguous recommendation on the choice of device. It all depends on the range of tasks that are planned to be addressed. In the presence of excess funds, it is most advisable to purchase a universal multimeter.