Electricity in our house makes life easier and more comfortable, but we must not forget that it can also cause serious electrical injuries. One way to protect yourself is to use protective grounding. In addition, some modern electrical appliances, such as microwaves, gas boilers, home computers, need grounding to ensure their normal operation (reducing noise, reducing the level of harmful radiation).
It is very rare to find a private house or cottage.using grounding. Owners of such housing face the choice of hiring workers or making the grounding themselves. For a network of 220 V (380v) to solve this problem is quite simple. Therefore, if you have the desire to physically work, there is no need to buy expensive kits of ready-made grounding or hire organizations to perform these works.
In the manufacturing process, you will need to perform a small amount of welding work, if there are no difficulties with this, it remains to purchase hardware and get to work.
1 Safety ground
- 1.1 Elements and materials
- 1.2 Schemes and sizes
- 1.3 Choosing a place
- 1.4 Ground check
- 1.5 Sequence of work
- 2 Protective zeroing
Most of our networks are equipped with a deafened grounded neutral, in simple terms, the neutral wire in the outlet at the power station is connected to earth. The wire is also grounded at additional points, for example, on power line poles. Unfortunately, the power supply is badly worn, and this grounding leaves much to be desired.
Now let us imagine a situation when, due to damaged insulation, the voltage fell on the body of the device. If you touch the device, the current will begin to flow through the human body to the ground. It is believed that the human body has a resistance of about 1 thousand Ohm, this size increases the rubber sole of the shoe, dry mat on the floor, etc.. The smaller this value, the stronger will be the effect of current on the body.
If ground is present, current from the damaged device will flow to the earth over it. If in this case the person touches the body of the device, then his body becomes parallel connected to the grounding conductor. The resistance of the latter is much less than the resistance of the body, so most of the current will flow along the path. the smallest resistance, and the person maximum will feel a slight tingling and avoid getting heavy electric shock
To make the circuit work like thisAs described above, the grounding system must have a certain resistance:
- for 380V mains - no more than 2 ohms;
- for 220V mains - no more than 4 ohms.
The design requirements for the grounding device of a private house with a 380 V network are higher, so this circuit can also be used for 220 V. When building, they differ only in that for 380 V, grounding conductors of a larger cross section are used, and the structural elements are made of thicker metal. Therefore, there is no need to separately consider how to make a ground loop of 380 V and 220 V. Consider making grounding for 380 V.
Elements and materials
The grounding device consists of three elements.
- Vertical earthing - metal elements that are driven into the ground, It is preferable to make them from a thick-walled pipe with a diameter of at least 32 mm or from a corner with a width of 40 mm.
- Horizontal elements that connect all vertical elements in one chain. A metal band of 40 × 4 mm is best for this purpose, but you can use a corner or a rod with a diameter of 16 mm or more.
- The grounding bus is a metallic conductor that goes from the grounding to the switchboard or to the equipment to be protected. For these purposes, you can use a strip of 40 × 4 mm. In order to save and for the convenience of making bends and turns, it is permissible to use a rod with a diameter of 10 mm. It is rather difficult to get a metal strip into a house or a switchboard. To facilitate this procedure do so. Bring the grounding bus to the outer wall of the house. At the end, a bolt with a M10 or M12 thread is welded, with which a copper wire with a cross section of at least 6 mm is attached.2. Further this conductor leads to the shield.
The larger the cross section of the metal elements used, the better the currents spread to the ground, and therefore the whole ground loop works better. In addition, thick metal will be destroyed by corrosion longer, so ceteris paribus metal should be chosen thicker.
The electrical conductivity of hardened metal is lower than that of ordinary steel, for this reason, do not use reinforcement, channel and similar elements of metal structures.
Schemes and sizes
The grounding circuit of a private house is a way to locate and connect vertical earthing switches. If you do grounding 380 volts to a house, the execution scheme may be different, but the main two.
- Closed - the contour is in the form of a geometric figure. Vertical pins are hammered into the corners, which are connected by horizontal elements, forming the sides of the selected figure. Most often, the contour is made in the form of an equilateral triangle. Side length 2.5−3 meters. The depth of immersion of vertical rods is about three meters. If necessary, the size of the side of the triangle can be reduced to 1.2 meters.
- Linear - the contour has the form of a straight or curved line. Vertical pins clog at a distance of 2.5−3 meters from each other and connect them in series with horizontal elements.
The dimensions of the ground loop for a private house, listed above, are suitable for most cases, but they can be changed depending on the specific conditions. For example, if on your site groundwater is located close, then the length of the vertical earthing can be reduced to a meter.
If it is not possible to deepen the earthing to the required level, or on a stretch of dry sandy soil, a situation occurs when the finished grounding has a high resistance and does not perform its functions. In this case it is necessary to increase the number of vertical pins. For example, if there is already a triangular contour, you need to retreat from it three meters and drive a rod that connects with a triangle with a metal band. It turns out the combination of closed and linear schemes of construction. You can make two triangles and connect them together. Do this until the loop resistance drops to the required value.
Choosing a place
The grounding device is located no closer than one meter from the house.
It is good if the land never dries up in a selected place, for example, a piece of land on the north side of a house, a lowland, and so on.
We should not forget about the precautionary measures, it is necessary to limit the visit to the place with the ground loop to animals and people. To do this, grounding should be placed where it is possible to find people, or fence it.
Before starting excavation work, make sure that pipelines and cables are not laid underground.
The method of measuring the grounding resistance differs from the measurement of ordinary resistance; therefore, special devices are used for such purposes. If you do not have such a device, you can test your circuit using a practical method.
You will need a cartridge with an incandescent lamp with a capacity of at least 100 watts. One wire from the lamp socket is connected to the phase contact of the socket, and the second to the ground bus. If the lamp is shining the same way as with a normal power connection, the circuit works correctly. Ideally, the voltage on the lamp in both cases should be the same.
In the case when the lamp shines dimly or does not burn at all, it is necessary to check the places of metal welding and wire connections. If the connections are normal, it is necessary to increase the ground loop.
Sequence of work
- Making the markup. Mark the locations of the vertical grounding, the location of the horizontal jumpers and the path that the grounding bus will pass to the house.
- You can start excavation work. All contour elements should be located below the ground surface, preferably below the freezing level, therefore the depth should be at least fifty centimeters. The width of the trench must be chosen in such a way as to ensure the convenience of performing welding operations and the procedure for the penetration of earthing.
- Preparing metal. Cut the blanks for vertical grounding and sharpen one of the ends. At the other end, it is desirable to weld the pad - this will reduce the riveting of the metal and facilitate the work. The horizontal jumpers should not be cut immediately, since when driving, the pins can go to the sides, and the practical lengths of the jumpers can differ from the calculated ones. To protect the metal from corrosion, it can be coated with special compounds that maintain the electrical conductivity of the steel. It is impossible to apply usual paints and varnishes.
- We hammer in pins. The length of the pins is about three meters, so at the beginning of this procedure you may need a stepladder. You can hammer the usual sledgehammer or use a powerful jackhammer. After deepening, the top edge of the pins will be deformed, and it is better to cut it to a flat part - this will facilitate welding work. You need to deepen the pins so that after trimming they are about 10 cm above the bottom of the trench.
- We cut metal for horizontal contour elements and proceed to welding. Boil should be a continuous seam of high quality. If you cannot do this, invite a specialist, as it is very important to ensure high-quality and reliable contact between all elements of the circuit.
- If the grounding bus is carried only to the house, then it should be brought to the wall and raised. This end should protrude twenty centimeters above the ground. At the end we weld the bolt to connect the ground wire.
- We make a test of the efficiency of the ground loop.
- If the circuit has passed the test, you can bury the trench.
Some people, in order to save or unknowingly, use zeroing in a private house instead of protective grounding. The scheme of the latter is used in enterprises when using industrial equipment. The main purpose of grounding is to protect equipment from short circuits. Therefore, its use in a private house is impractical, and it can not replace the protective ground.
Do not save on their security. To make grounding for 220 V in a private house with your own hands is easy. All the necessary tools are available for each owner.
If the wiring in your house is made with twin wires, then there is no wire for connecting the grounding conductor. This problem can be solved without replacing the wiring in the following way. The sockets in the house are replaced with ordinary sockets with grounding, and the ground wire is led along the outer surface of the wall, you can hide it under a plinth or in a decorative plastic box.
For the safe operation of powerful electrical appliances, especially those located in wet areas (boiler, washing machine), the use of a grounding contact in the outlet is not enough. The housings of such devices must be connected with copper conductors directly to the grounding bus. To do this, there is a special bolt on the body, marked with a ground symbol.
The earthing elements are made of ferrous metal, which under the action of corrosion will gradually deteriorate, and at some point the grounding will cease to perform its functions. In order not to miss this moment, it is necessary to periodically check the performance of the circuit and, if necessary, restore it. Therefore, it is useful to draw a plan for the location of all elements.