The safety of electrical wiring is a prerequisite for any apartment or house. Grounding ensures the safe operation of electrical household appliances. It can also save a person from electric shock in the event of a breakdown of a phase conductor, a violation of the insulating layer, and an accumulation of potential on metal parts. Before you make a socket with grounding in an apartment or in the country, you need to understand the peculiarities of the power supply circuit in the apartment.
Why do you need grounding and its types
Grounding is a way to ensure the safety of people and household appliances. When electronic equipment breaks down, a charge accumulates on the case. If a person touches live metal, an electric shock will occur. Grounding is used so that the current and potential from the case go to the ground, do not harm humans.
The electrical network must necessarily consist of a phase and zero. Additionally, a protective conductor - grounding can be connected. There are different schemes for connecting the grounding conductor - it may be absent, connected together with a neutral wire, or stand out in a separate conductor.
Before choosing a grounding scheme, you need to find out which scheme is used in the house. It is laid even at the stage of building construction and installation of electrical wiring. There are 6 schemes in total, the most common are:
- TN-C. The electricity supply is carried out using a four-wire system. 3 cores extend from the phase conductor, the fourth wire is simultaneously zero and ground and is marked PEN (PE - ground, N - zero). Such a connection is unsafe for human life. In the event of a ground break, electrical appliances will stop working and the device will be energized. Potential builds up on metal parts, which can be fatal if accidentally touched by a person. Installing protective devices like an RCD will not help. From such schemes, you need to move on to TN-C-S, TN-S.
- TN-C-S. Similar to the previous circuit, power is supplied here through a four-wire system. In a certain section of the PEN circuit, the wire is broken to ground and zero. A separate ground loop is installed at the branching point. For additional protection, an RCD should be provided in the circuit, since before the rupture, the conductor carries a potential threat.
- TT. This scheme is used in domestic networks. It is also four-wire, in which there are 3 phases and one zero. There is no ground, but it can be connected. The scheme is adjusted individually for each room.
After choosing the scheme, you can proceed to the installation of the outlet
Connecting a grounded socket
To close the outlet with your own hands, you must follow the algorithm:
- phase and zero disconnection;
- disconnection of the power supply;
- fastening the contacts of the socket to the phase and zero;
- connecting the ground wire to the outlet;
- installation of a protective housing for an electrical outlet.
Before making grounding in the outlet, you can determine the phase and zero using an indicator screwdriver or a tester. Phase and zero from the wiring must be connected to the corresponding terminals of the socket. The grounding conductor is connected to the terminal, which is located between the phase and neutral contact.
If there is no grounding conductor, grounding must not be performed. This will lead to the fact that when zero disappears, a short circuit will occur, which can cause a fire or knock out plugs on the machine.
Grounding in the house
- without a grounding loop;
- with a grounding loop.
In the absence of a circuit, a steel pipe or metal parts on a wooden post acts as a grounding structure. Using this method, two conditions must be observed - the minimum depth must be 1 meter and the current spreading must be no more than 4 ohms at 220 V.
A ground loop circuit has a distribution bus from which the entire system begins. All metal parts of the circuit must be securely connected to each other. For this, welding of the components is used.
When creating a contour, the following mistakes are most often made:
- Unreliable connections of parts. Poor contact leads to oxidation and rust formation, which can destroy the circuit. It is important to make a good connection.
- Choosing the wrong metal. Metal fittings are not suitable for connection - the uniformity of the current distribution is disturbed in it.
Do not paint the contour. The paint does not protect it from corrosion, but only adds resistance, which reduces the grounding effect.
Protection in the absence of grounding
If there is a ground terminal in the wiring of the riser, ground is connected to it. This is the easiest way. Otherwise, you need to choose a different method.
How to ground the outlet if there is no ground wire:
- Using an RCD. This method is used when there is no ground terminal in the wiring. The RCD is installed on the line through which powerful household appliances with a metal case (dishwashers or washing machines, water heaters) are connected. It should be borne in mind that the RCD does not provide full protection. This is only a temporary method until the installation of the ground loop.
Ground loop diagrams - Installation of your own circuit. The creation of a ground loop is carried out in several stages. First, a place is chosen where the earthing switch will be installed. Do not place it in rocky soil, garbage dump or building material unloading place. Next, the scheme and materials are selected - the ground electrode can be installed vertically or horizontally, made of copper or steel, the type and dimensions are selected. The earthing switch is installed in the trench. Its depth for horizontal installation is from 20 to 50 cm, for vertical installation - 100 cm. The assembled circuit is connected to a common loop and the resistance of the ground electrode is measured. The last step is to connect all metal structures.
The grounding must be carried out correctly. There are dangerous ways that can lead to an irreparable situation:
- Grounding cable connection to zero. If the zero core is broken, a fire may occur.
- Ground connection to plumbing or heating system. In the event of a breakdown of the insulating layer, all elements will be energized. Touching them leads to negative consequences for health and life.
- Connection to fittings of the nearest high-voltage line. The potential from the line can go to the armature, which will violate the protective properties of the insulator, overvoltage or other dangerous consequences will occur.
Such methods are strictly prohibited by the rules of the PUE and SNiP. When using these methods, not only the owner of the apartment is at risk, but also his neighbors. In no case should you ground yourself in this way.
