Electrical outlets are accessories familiar to the potential user. They are used everywhere: in the house, at work, in public places, etc. According to technical standards, sockets must be grounded - this will protect households from electric shock when electrical appliances break down.
However, you must admit that it is unlikely that any of the consumers can confidently say that all the outlets in the house or apartment are grounded. To find out the location of the wires in the wiring, you need to conduct a series of tests.
We will tell you how to check the grounding in the socket in various ways - according to external signs and using special tools.
Typical outlet design
The use of receptacle grounding verification techniques may be required at any time. Especially for people who have to work with specific electrical outlets repeatedly.
This part of the electrical network (household or industrial) has a simple structure.
Structural difficulties the electrical outlet does not shine. Uncomplicated ceramic or plastic base plus a metal frame with a cover. And yet, electrical outlets are improving
The electric socket consists of a plateau of round or rectangular shape. A plateau is made based on materials that do not conduct electricity.
Typically, for the manufacture of a plateau of sockets used:
- ceramics;
- porcelain;
- plastic.
The back of the plateau has a flat surface, and on the front there are curly landing pads for electric contactors. The material of the contactors is usually copper. The contactors are fixed to the plateau firmly - using rivets, plus they are embedded in the body of the plateau.
To connect to the electrical wiring, the contactors have fixing screws. The whole structure is closed by a lid having two through holes for an electric plug.
Types of electrical outlets
The industry produces two types of products:
- equipped with a ground bus;
- not having a ground bus.
The first type of structure is often called the "Euro-socket". This design fully meets the requirements of electrical safety. When changing wiring, it is recommended to install sockets with grounding.
Appearance of the electrical outlet according to the standards established by the EU countries. A distinctive design feature is the presence of contact bimetallic grounding plates
The second type of product is considered an obsolete modification, but is still found in practice. Especially many outdated sockets are used in old buildings.
Design variant without specific country affiliation. For modern electricians, it is considered an obsolete model, which is not recommended for installation due to increased danger due to the lack of a ground contactor
Both types of products are made for internal or external installation. According to the new PEB recommendations, modifications of sockets for internal installation should include bimetallic plates with a ground contactor as part of the design.
For electrical outlets for external installation, the recommendations are the same, but in some cases their use is allowed two-wire interface.
Grounding the outlet and methods of verification
Checking for grounding on electrical networks may be required in different cases:
- when changing your place of residence;
- in case of rental of any real estate;
- when buying an office or business;
- when doing work on a third-party territory, etc.
Consider common verification methods.
External check
The initial and simplest verification of the presence of grounding is done visually by external signs. It is enough for a potential user to evaluate the external interface of an electrical outlet in order to draw certain conclusions for himself.
External signs of an electrical outlet, by which it is possible to judge the presence of an earth bus: 1, 2 - working contactors; 3, 4 - bimetal plates of the grounding bus (+)
So, if characteristic details indicating the presence of a grounding bus are present inside the outlet bowl, 50% testing can be considered successful. Such details are special slots in the body of the product and contact bimetallic plates looking through these slots.
These grounding "whiskers" are usually located in the upper and lower regions of the outlet bowl.
Analysis of the internal "filling"
To make sure that the outlet is grounded with a 75% probability, you will have to open the product case - unscrew one screw that holds the socket cover and remove it.
But before doing this work, you should turn off the electrical communications - turn off the power input automaton, which is usually installed inside the mounting panel box, which is located on the staircase of the staircase (option for municipal housing).
After opening the outlet, the user will see the entire existing layout of conductors connected to the instrument mounting terminals.
For the circuit for the execution of the "euro", a characteristic sign of the wiring is the presence of three conductors:
- phase;
- zero;
- grounding.
The colors of the wires of the first two conductors may vary. However, according to the established specifications, the phase is usually supplied with a wire with insulation colors brown or white, and zero with insulation colors blue or black. But in practice, everything can be very different.
A good example from everyday practice, when the standards for connecting electrical outlets are completely ignored. In particular, the connection is made by conductors, the colors of which do not comply with the rules
The third conductor is grounding, it is specifically painted in green or yellow-green. In addition, this wire, as a rule, has an enlarged section. The grounding conductor inside the housing of the outlet is connected to the contact of the bus, which, in turn, has a direct connection with the bimetal plates of the "euro" interface.
In this picture, conductors that fully comply with the rules for installing electrical networks are displayed through the mounting channel. The colors of the wires in this case are correct. The ground wire has a larger cross section
So, the presence of a connected wire (yellow-green, green) on the ground bus is already a 75% guarantee that the grounding in the socket is done.
It remains only to check the operability (integrity) of the grounding bus using special devices.
Instrument Testing
Testing technique with control devices gives a 100% guarantee of the presence of grounding in the socket. But the method of verification with the help of special devices is allowed to be used only by persons with appropriate tolerances. This is an important point, because testing with devices, as a rule, is performed with the voltage connected.
Supply voltage to the apartment electrical network, including to sockets, which must be checked by devices for the operation of the grounding bus. The shield can be located directly in the apartment or in the entrance
Household sockets are powered by voltage 220 V (sometimes voltage 110 V). When the power is connected, it becomes a real danger for people testing the elements of the mains. Especially for those who have no idea about the principle of operation of electrical networks.
Incandescent lamp test
The first simple way of checking is done using a conventional incandescent lamp, designed for the voltage of an existing network.
The inspecting person for work needs to make simple equipment:
- Take an electric lamp holder.
- Connect a two-wire wire (20-30 cm) to the cartridge.
- Screw in incandescent bulb.
The ends of the cartridge conductors must be stripped 7-10 mm from the edge. If the conductors are stranded, tightly twist the wires of the stripped ends. For greater safety, you can equip the wire lugs. This completes the preparation of the snap, you can proceed directly to the test.
The following photo gallery will demonstrate the process of determining grounding using a light bulb:
Image Gallery
Photo from
Situations dictating the need to verify the correctness of the wiring device often arise in new buildings. Especially in long-term construction, in which work before the commissioning is carried out by inexperienced shabashniks, guest workers. Not always in these cases, you can focus on the color of insulation
If we don’t have a multimeter at our disposal, the electrical circuit with a control lamp will help you find the ground wire exactly.
In order to secure the conduct of determinations empirically, we will twist the lamp in the cartridge. Connect the wire with stripped conductors to the terminals of the cartridge
To find the ground wire, we first determine which one is the phase. If the light comes on when you touch the wires from a homemade circuit, then one of them is zero, the second phase
In fact, if we wanted to find a ground wire, further research can be left. After all, the third wire is earth. But it is better to study the situation thoroughly
If, when connecting the wires of the circuit we assembled to the ground wire and to either of the two wires, the lamp does not light up, then one of them is exactly the ground, the second is zero or phase
If the lamp flashes at the moment when changing the wires while maintaining contact with the ground, then the second conductor is zero. A quick shutdown here is done by an RCD or automatic
If the lamp lights up in two positions, and there is no RCD or machine on the branch under investigation, disconnect the ground line terminal in the shield. We check all current-carrying conductors in pairs as well. Earth will be the one where the light is off
Step 1: Wires Prepared for Connection
Step 2: Assembling the circuit with a warning lamp
Step 3: Screw the lamp into the socket
Step 4: Determine the phase conductor
Step 5: Search for the neutral and phase wires
Step 6: Isolating Zero from Three Conductors
Step 7: Determine Zero by Brief Flash
Step 8: Identify the cores in the line without an RCD
Turn on the power supply circuit, which includes the outlet. Take a cartridge with a lamp and connect the ends of the wire to the usual contactors of the outlet (phase - zero). The lamp should shine brightly. Such a connection indicates the integrity of the electrical circuit, as well as the serviceability of the equipment made. This test step must be performed.
Next, check the operation of the grounding. The end of any conductor from the lampholder to the lamp is connected to the ground bus contactor, and the remaining free end is alternately connected to the socket contactors.
If either of the two connections lights the lamp, this means that the ground bus is working and connected to ground. Test passed successfully. Otherwise, the outlet is not grounded.
Testing with an arrow (digital) voltmeter
For the second test method of grounding bus will require a pointer or electronic device that measures voltage. A standard tester, for example, the Ts4353 model, is suitable here.
A special measuring device of the arrow type, which measures not only voltage (constant or variable), but also current strength, resistance, inductance. It is always advisable to have such a device at hand.
The measuring range of the device by voltage (alternating) should have an upper limit of at least 600 V. The very principle of testing is similar to testing with a lamp. Only instead of the backlight, the instrument scale will already be used for control.
Step-by-step verification performance with a pointer tester:
- Set AC voltage measurement mode.
- Set the measuring range to 600 V.
- Connect the probes to the socket contactors (phase - zero).
- Record the readings on paper.
- Connect one test lead to the ground contactor.
- In turn, connect the second probe of the device to the socket contactors.
- Record the readings on paper.
Now you should compare the recorded readings obtained during the verification process in step 6. If either of the two readings is equal to or slightly less than the value obtained in step 4, this means that the ground bus is working. The absence of any indications of the device indicates a non-working or ragged “ground”.
Image Gallery
Photo from
Portable screwdriver multimeter
Checking the conductors before installing the device
Earth Search with a Digital Multimeter
Ground wire zero voltage
Similarly, the procedure is performed by a digital voltmeter equipped with a liquid crystal display. Here the only difference in the work is a more convenient perception of the measurement result. The digital analogue of the dial gauge is a multimeter. It is convenient in that it displays the measurement result on the screen in the form of digital values. Meanwhile, the degree of reliability and accuracy of measurements is inferior to the switch device.
A detailed instruction for checking the voltage in the outlet is presented in this article.
When you need to open the outlet
By and large, all of the above methods for testing the presence of grounding can be performed without removing the outlet cover. But then guarantees of 100% are not possible for one simple reason.
Often in practice there are examples when the grounding bus of someone "skillful handles" is connected to the zero bus. This is done by a wire jumper installed between zero and the ground contactor.
Such incidents are often found in everyday practice when servicing the electrical facilities. This is an unacceptable and rude, from the point of view of security, action. It is not permissible to combine a zero contactor with a grounding contactor
Without dismantling the cover, such a "work of art" cannot be found. At the same time, a check with instruments will show the presence of land. There is a risk of error. Therefore, opening the lid is always relevant in case of verification.
From the point of view of security for users with outlets, connecting the “zero” to the “ground” looks like an extremely unsuccessful and unacceptable action.
The ground bus according to the rules of electrical installation is always considered as a separate communication line, indirectly tied to the wiring diagram in an apartment or house.
And the neutral conductor at any time by negligence or inexperience of the maintenance personnel can be moved to the phase conductor. The consequences are clear without a word.
The use of grounded electrical outlets in the home is gradually becoming the norm. Now, every modern building is equipped with an electric facility, which provides for the mandatory installation of circuit elements with a ground bus to them.
This ensures a high degree of safety for people operating buildings using sockets for working with various household appliances.
The nuances of installing an outlet with grounding can be found using the video material:
By the way, it will be noticed: in the presence of a grounding bus in sockets, the degree of reliability of household appliances increases. Particularly critical to the lack of "ground" is the response of digital equipment, and such is now present everywhere.
Tell us which method you use to test the grounding in outlets. Share your own skills with readers, participate in discussions, and ask questions. The comment box is located below.