How to check grounding in an outlet: methods of checking using instruments

Electrical sockets are accessories familiar to potential users. They are used everywhere: at home, 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 consumer can say with confidence that all sockets in a house or apartment are grounded. To find out the location of the wires in the electrical wiring, it is necessary to carry out a number of tests.

We will tell you how to check the grounding in an outlet in various ways - by external signs and using special tools.

Typical socket design

Using the socket grounding test technique may be necessary at any time. Especially for those people who will have to work with specific electrical outlets repeatedly.

This part of the electrical network (domestic or industrial) has a simple design.

The electrical outlet does not shine with design difficulties. A simple ceramic or plastic base plus a metal frame with a lid. Still, electrical outlets are improving.

The electrical outlet consists of a round or rectangular plate. The plateau is made from materials that do not conduct electricity.

Typically, the following is used to make socket plates:

• ceramics;
• porcelain;
• plastic.

The back of the plateau has a flat surface, and on the front there are shaped landing pads for electrical contactors. The material of contactors is usually copper.The contactors are fixed to the plateau rigidly - using rivets, plus they are embedded in the body of the plateau.

For connection to electrical wiring, the contactors have mounting screws. This entire structure is closed with a lid that has two passage holes for an electrical plug.

Types of electrical outlets

The industry produces two types of products:

• equipped with a grounding bus;
• not having a grounding bus.

The first type of design is often called a “euro-socket”. This design fully satisfies electrical safety requirements. When changing electrical wiring, it is recommended install grounded sockets.

The appearance of the electrical outlet according to the standards established by the European Union countries. A distinctive feature of the design is the presence of contact bimetallic grounding plates

The second type of product is considered an outdated modification, but is still found in practice. Especially many outdated sockets are used in old buildings.

Design option without specific country affiliation. For modern electricians, it is considered an outdated model, which is not recommended for installation due to increased danger due to the lack of a grounding contactor

Both types of products are made for indoor or outdoor installation. According to the new PEB recommendations, modifications of sockets for internal installation must have bimetallic plates with a grounding contactor as part of the design.

For electrical sockets for external installation, the recommendations are the same, but in some cases of their use a two-wire interface is allowed.

Grounding the outlet and testing methods

Checking the presence of grounding on electrical networks may be required in different cases:

• when changing place of residence;
• in case of renting any real estate;
• when buying an office or business;
• when they do work on third-party territory, etc.

Let's consider the generally accepted verification methods.

Checking by external signs

The initial and simplest check for the presence of grounding is done visually based on external signs. A potential user only needs to evaluate the external interface of the electrical outlet in order to draw certain conclusions.

External signs of an electrical outlet, by which one can judge the presence of a grounding bus: 1, 2 – working contactors; 3, 4 – bimetallic plates of the ground bus (+)

So, if inside the socket bowl there are characteristic details indicating the presence of a grounding bus, testing can be considered 50% successful. Such details are special slots in the body of the product and contact bimetallic plates visible through these slots.

These grounding “whiskers” are usually located in the upper and lower areas of the socket 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 holding the outlet cover and remove it.

But before doing this work, you should de-energize the electrical communications - turn off the automatic power input device, which is usually installed inside the installation panel box, which is located on the staircase of the entrance (an option for municipal housing).

After opening the socket, the user will see the entire existing layout of conductors connected to the mounting terminals of the device.

For a Euro circuit, a characteristic feature of the wiring is the presence of three conductors:

• phase;
• zero;
• grounding

May vary wire colors the first two conductors. True, according to established specifications, the phase is usually supplied with a wire with insulation colors of brown or white, and zero with insulation colors of blue or black. But in practice, everything can be completely different.

A clear example from everyday practice when standards for connecting electrical outlets are completely ignored. In particular, the connection is made with conductors whose colors do not comply with the rules

The third conductor is the grounding conductor, specifically painted green or yellow-green. In addition, this wire, as a rule, has an increased cross-section. The grounding conductor inside the socket body is connected to the bus contact, which, in turn, has a direct connection with the bimetallic plates of the “Euro” interface.

In this picture, conductors are routed through the installation channel and fully comply with the rules for installing electrical networks. The color of the wires in this case is correct. The grounding wire has an increased cross-section

So, the presence of a connected wire (yellow-green, green color) on the “ground” bus is already a 75% guarantee that the grounding in the outlet has been completed.

All that remains is to check the functionality (integrity) of the grounding bus using special instruments.

Testing with instruments

The testing method with control devices provides a 100% guarantee of the presence of grounding in the outlet.But the verification method itself using special instruments is allowed to be used only by persons who have the appropriate permits. This is an important point, because testing with devices is usually performed with the voltage connected.

Supplying voltage to the apartment electrical network, including sockets, which need to be checked with devices for the functionality of the grounding bus. The shield can be located directly in the apartment or in the entrance

Household sockets are powered by a voltage of 220 V (sometimes by a voltage of 110 V). When the power is connected, there is a real danger for persons testing the elements of the electrical network. Especially for those who have no idea about the principle of operation of electrical networks.

Incandescent lamp test

The first simple test is done using a regular incandescent lamp, designed for the voltage of the existing network.

For the job, the inspector needs to make simple equipment:

1. Take an electric lamp socket.
2. Connect a two-core wire (20-30 cm) to the socket.
3. Screw the incandescent lamp into the socket.

The ends of the cartridge conductors must be stripped 7-10 mm from the edge. If the conductors are multi-core, the conductors of the stripped ends should be twisted tightly. For greater safety, you can equip the wire with lugs. This completes the preparation of the equipment, and you can proceed directly to the test.

The following photo gallery will clearly demonstrate the process of determining grounding using a light bulb:

Include circuit breaker, where the socket goes.Take the socket with the lamp and connect the ends of the wire to the usual socket contactors (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 completed.

Next, check the grounding operation. The end of any conductor from the lamp socket 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 up the lamp, this means the ground bus is working and connected to ground. The test was completed successfully. Otherwise, the outlet is not grounded.

Testing with a pointer (digital) voltmeter

For the second method of testing the grounding bus, you will need a pointer or electronic device that measures voltage. A standard tester, for example, model Ts4353, is suitable here.

A special pointer-type measuring device that measures not only voltage (DC or AC), but also current, resistance, and inductance. It is advisable to always have such a device on hand.

The voltage (alternating) measurement range of the device must have an upper limit of at least 600 V. The testing principle itself is similar to testing with a lamp. Only instead of backlighting, the instrument scale will be used for control.

Step-by-step execution of the test using a pointer tester:

1. Set the AC voltage measurement mode.
2. Set the measuring range to 600 V.
3. Connect the probes of the device to the socket contactors (phase - zero).
4. Record the instrument readings on paper.
5. Connect one probe of the device to the grounding contactor.
6. Connect the second probe of the device to the socket contactors one by one.
7. Record the readings on paper.

Now you should compare the recorded readings obtained during the test 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 readings from the device indicates a non-working or broken “ground”.

The procedure is performed in a similar way with a digital voltmeter equipped with a liquid crystal display. Here the only difference in operation is a more convenient perception of the measurement result. Digital analogue of a pointer instrument – multimeter. It is convenient because it displays the measurement result on the screen in the form of digital values.Meanwhile, in terms of reliability and accuracy of measurements it is inferior to a pointer instrument.

Detailed instructions for checking the voltage in the outlet are presented in this article.

When to open a socket

By and large, all of the above methods for testing the presence of grounding can be performed without removing the outlet cover. But then 100% guarantees are not possible for one simple reason.

Often in practice there are examples when the grounding bus is connected by someone’s “skillful hands” to the zero bus. This is done by a wire jumper installed between the zero and the ground contactor.

Such incidents are often encountered in everyday practice when servicing electrical equipment. This is an unacceptable and rude action from a safety point of view. It is unacceptable to combine a neutral contactor with a grounding contactor

Without dismantling the cover, such a “work of art” cannot be discovered. At the same time, checking with instruments will show the presence of earth. There is a risk of error. Therefore, opening the lid is always important in case of inspection.

From a safety point of view for users of sockets, connecting the “zero” to the “ground” looks like an extremely unfortunate and unacceptable action.

According to the rules of electrical installation, the earth bus is always considered a separate communication line, indirectly tied to wiring diagram in the apartment or home.

And the neutral conductor at any time, due to the negligence or inexperience of the maintenance personnel, can be moved to the place of the phase conductor. The consequences are clear without further ado.

The use of grounded electrical outlets in everyday life is gradually becoming the norm.Now every modern building is equipped with electrical facilities, which provide for the mandatory installation of circuit elements with a grounding bus connected to them.

This ensures a high degree of safety for building operators who use sockets for working with various household appliances.

Conclusions and useful video on the topic

You can familiarize yourself with the nuances of installing a grounded outlet using the video:

By the way, it will be noted: if there is a grounding bus in the sockets, the degree of reliability of household appliances increases. Digital equipment reacts especially critically to the lack of “ground”, and such equipment is now present everywhere.

Tell us what method you use to check grounding in sockets. Share your own skills with readers, participate in discussions and ask questions. The comment box is located below.