Even in the relatively recent past, few people thought about the need for a high-quality grounding device. And even now, many do not pay due attention to this, considering the presence of zero and phase sufficient for the normal operation of household appliances. Meanwhile, it provides the necessary protection, especially when included in the RCD circuit. When moving into a new apartment, you should check the presence of a tire in the switch cabinet. However, this is not the only thing that needs to be done. After all, the fact that there is a bus does not guarantee the correct connection in sockets. Today's article will tell you how to check grounding with a multimeter, as well as with the help of other devices that are always at hand.
What is the circuit for and why is it connected?
It is not uncommon for high humidity to cause voltage to break through to the body of household appliances such as a washing machine or dishwasher. electrical discharge, whicha person receives when in contact with the surface of such a device, it cannot be called strong, but it is quite unpleasant. If there is a breakdown of the insulation of the phase wire to the case, everything can be more serious, even fatal.
Protective grounding is switched with a contact connected through a wire to the body, and the voltage that has arisen goes through it, which is always directed along the path of least resistance. It is for this reason that a person is completely safe. If a residual current device is provided in the switchboard, then it catches this leak and turns off the power supply. But in order to make sure that such protection exists, you should know how to check the grounding in the outlet with a multimeter or other devices.
Preliminary visual inspection
First, you need to determine if the ground wire is suitable for the outlet and if it is connected correctly. To do this, using an indicator screwdriver, we check all three contacts of the connection point. The light bulb should light up only when in contact with the phase contact. It should be noted - this information will come in handy later. After that, it is necessary to turn off the introductory machine and check the socket again with the indicator, making sure that there is no voltage.
Next, the outer decorative overlay is removed so that the contacts are visible (often for this you have to remove the device from the "glass"). Making sure that the groundit is the yellow-green wire that fits the contact, and there is no jumper installed between it and the zero terminal, you can assemble everything in the reverse order and resume the power supply. Now you can move on to the question of how to check grounding with a multimeter.
First Verification Steps: What You Need to Know
To do this job you will need nothing but a pen, a piece of paper and a measuring device. It doesn't matter if it's analog or digital. Before checking the quality of grounding with a multimeter, you should set its switch to the maximum AC value. For various models, it can be 700, 750 or 1000 volts.
One of the probes is connected to the previously marked phase contact. The second one is first switched to zero, and then to the grounding bracket. Instrument readings in both cases are recorded for comparison. If they are perfectly the same, this is a reason to doubt the absence of a neutral conductor and ground connection in one of the junction boxes or sockets. We'll have to start a long and painstaking search.
Checking the circuit with an incandescent lamp
Before making sure that the yellow-green wire is connected to the correct pin, before checking the ground with a multimeter, you can test with a conventional socket with wires and a lamp. Such work does not require special skills, but you should not forget about attentiveness and accuracy - all checks are made with the voltage on. One ofthe stripped ends of the wire coming from the cartridge with the lamp are connected to the phase contact. The second, to check the performance, is first connected to zero - a glow should appear. Further, instead of a neutral terminal, the core is switched with a grounding bracket. Next 3 scenarios:
- Lamp does not light - missing or faulty ground connection.
- The device is working at full capacity - either the circuit is in order, or there is a contact with zero. Further verification is needed with more sophisticated devices.
- Half-incandescent lamp brightness is ideal where no further testing is required. It means the presence of a working ground and its correct connection.
Checking the connection of the circuit in the presence of RCD
Everything is much simpler here. To do this, you don’t even need to know how to check grounding with a multimeter in a private house or apartment. The presence of an RCD that does not work indicates that there is no zero contact with ground. This means that if the residual current device is working properly (you can check it by pressing the “test” button - a cut-off should occur), then either the circuit is not connected as expected, or there is no such switching at all, and the wire in the sockets is mounted only for visibility.
To work, you only need a piece of wire with stripped ends. They should connect the zero contact of the socket and the grounding bracket. At this point, the residual current device should operate, disconnecting the circuit andremoving the voltage from the home electrical network.
Checking ground resistance in a private house
Often the circuit itself turns out to be inoperative. If it is made of steel tires, normal corrosion can render it unusable. However, the question "how to check the ground resistance with a multimeter" is incorrect. For such tests, another device is used, which is called a megohmmeter. In order to use it, specialists undergo special training. It can only be noted that the grounding resistance for a single-phase voltage of 220 V should be 4 ohms. The same figure is required for a three-phase network 380 V.
RCD testing
If there is an RCD in the switchboard, before checking the ground loop with a multimeter, it makes sense to make sure that the protection is working. If the home master does not trust the "test" button, you can conduct your own tests. For this, the RCD is completely disconnected from the network, and pieces of wire are connected to its input and output contacts (one of the two). For example, take the top and bottom phase terminal. The flag is moved to the “On” position, after which a conventional 1.5 V battery is connected to the free ends. The field created on one coil and its absence on the second creates the appearance of a leak, as a result of which a cutoff should occur. If this does not happen, the device is faulty.
What can be said in conclusion
A properly installed and connected ground loop is necessary, because one day it can save not only the he alth, but also the life of people living in the house. Do not underestimate its role in the protection of the home electrical network. In addition, according to statistics, household appliances connected to sockets with grounding last much longer. The main thing is that the circuit is operational and correctly connected to the home network. And one conclusion can be drawn: every home master is obliged to know how to check grounding with a multimeter or other devices.
