Years, since it will be possible to immediately more or less accurately measure the resistance value of the grounding device. And it will be much easier to dig the ground on dry ground.
It is easier to make grounding yourself from a black steel corner 50x50x5 mm and a steel strip 50x5 mm, connection by the method and using the grounding bus. Steel corners must be unpainted.
There is an opinion that the grounding electrodes should be located in the place of the personal plot where it is most humid, that is, where the soil is shaded, and where rainwater is drained. But this is not entirely true, since rainwater moistens the soil to a depth of 1-1.5 m. Deeper soil layers remain unchanged throughout the year, and it is in this layer that ground rods should be located.
It is most optimal to arrange grounding from the side of the most electrified premises of the house. This will reduce the cost of the grounding conductor material.
Grounding installation consists of the following main steps:
1. earthworks;
2. hammering corners;
3. connection of corners and connection to the grounding bus;
4. connection of the protective conductor to the grounding bus;
5. measurement of the resistance of the resulting grounding device.
1. Earthwork
For earthworks the following tools are required:
- Bayonet shovel;
- Scoop shovel;
- Scrap.
A pit for mounting an earthing electrode. Trench 3 m long for two rods 2.5 meters high.
To make it easier to hammer in the grounding corner 50x50x5 mm, you need to remove the top layer of soil.
For those who do not like to do unnecessary work, I advise you to first dig a hole 50x50 cm to the depth of freezing. Usually, this is about 1 m for the middle lane. This will hammer in one electrode. Next, you should measure its resistance, after which you can calculate the number of electrodes required for the ground loop. Usually, in clayey soils, three corners of 2.5 m each are enough.
2. Driving in ground corners
It is not so easy to hammer a steel corner 50x50x5 mm to a depth of 2.5 m with a sledgehammer manually. But you can go for a little trick, and to make it easier for yourself, you need to sharpen the end of the corners at an acute angle, for example, using a "grinder". The optimal angle is about 20-30 degrees, it is not advisable to do less, otherwise the end of the corner may begin to bend strongly if it hits a pebble.
If you use the advice of this article, and dug a trench for corners with a depth of at least 1 m, then you can hammer in a corner with a height of 2.5 m just standing on the ground, in the worst case, standing on a low chair. One strong blow with a sledgehammer clogs the corner by about 1 cm.
Do-it-yourself grounding device with a tricycle
3. Connection of corners and connection of the ground bus
When you kill the corner, their ends will splash strongly. This is normal for everyone. You just need to cut off the splashes at the end of the corners, and connect the corners of the 50x5 mm steel strip by welding.
When welding, you will need to make three welds - two lateral vertical and one horizontal on top of the steel strip, which ensures maximum welding quality. Any mild steel electrode is suitable for welding.
Welding a steel strip with a corner: 1. steel strip, 2. an angle, 3. a welding seam Welding a steel strip with a corner: 1. steel strip, 2. an angle, 3. welding seam Grounding from a galvanized profile in line
4. Connecting the protective conductor to the ground bus
This is a very crucial stage, if you do a hack, then sooner or later the contact point will begin to rust, the resistance will deteriorate sharply and there will be no sense in grounding. Copper conductor must be insulated and have a cross-sectional area of \u200b\u200b10 mm 2. The conductor itself must be laid in a plastic corrugation, and the junction must be closed with a box.
Fastening the grounding conductor to the steel strip 50x5 mm using galvanized washers. Connecting the ground loop to a copper earth conductor with a diameter of 4 mm2. Connecting a ground loop to a copper earth conductor with a diameter of 4 mm2
Use galvanized fixing parts! Unprotected black steel forms a galvanic pair with copper and quickly rusts, i.e. the copper wire should only touch the galvanized washers and not directly touch the steel strip. The very same steel headquarters, before connecting the conductor, must be cleaned from rust at the attachment point.
Measurement of resistance of the ground loop Vimiruvannya of resistance of the ground loop 5. Measurement of the resistance of the obtained ground loop
It is better to entrust the measurement of grounding resistance to specialists, especially if you have never held an ohmmeter in your hands. The resulting resistance of the building ground loop should be no more than 47 ohms. This is the permissible resistance of the ground loop with the mandatory use of an RCD with a minimum leakage current of 30 mA.
If it was possible to keep within the 47 Ohm resistance immediately after the installation of the grounding, it will be necessary to repeat the measurements twice at the seasons unfavorable for the electrical conductivity of the soil: in the dry warm season and in the cold season. The resistance value must remain within acceptable limits. The article "Protective grounding of the house" substantiates the need to use a ground loop for a private house.
What is the difference between the concepts of "grounding", "grounding device" and "ground electrode"?
Grounding, grounding device, and earthing switch are three different terms that should not be confused.
Grounding is understood as the deliberate connection of parts of an electrical installation to a grounding device. Thus, unlike a grounding device and a ground electrode system, grounding is a process, an action.
A grounding device is a combination of a grounding electrode and grounding conductors, and a grounding device is a conductor or a group of conductors that are in direct contact with the ground and connect certain parts of electrical installations with it.
Grounding devices, depending on the purpose, can perform different functions.
These devices are divided into protective, working and lightning protection.
- Protective grounding devices are designed to protect people and animals from electric shock in case of accidental shorting of the phase conductor to non-current-carrying metal parts of the electrical installation.
- Working grounding devices are necessary to create a certain mode of operation of an electrical installation in normal and emergency conditions.
- Lightning protection grounding devices are used to ground rod and catenary wire lightning rods and arresters and are designed to divert lightning impulse current into the ground.
In many cases, one and the same grounding device can combine several functions (for example, be protective and operational). All ground electrodes are divided into two main types. It is customary to distinguish between natural and artificial grounding conductors.
Natural grounding conductors include water and other metal pipelines laid in the ground (with the exception of pipelines for flammable or explosive liquids and gases); casing; metal structures and fittings reinforced concrete structures buildings and structures; lead sheaths of cables laid in the ground, provided that at least two of them are laid and if there are no other grounding conductors, etc.
Pipelines coated with insulation to protect them from corrosion, pipelines for pumping flammable liquids and gases, aluminum cable sheaths and bare aluminum conductors must not be used as grounding conductors.
Artificial ground electrodes include structures made specifically for grounding. These can be steel rods and substandard pipes, vertically buried in the ground, angle steel, horizontally laid steel strips, round steel rods, etc.
The grounding conductor is designed to connect the grounded parts of electrical installations to the ground electrode. As grounding conductors, you can use metal structures of buildings and structures, as well as metal structures for industrial purposes, for example steel tubes electrical wiring, aluminum sheaths of cables, metal stationary openly laid pipelines of any purpose (except for those intended for the transportation of flammable and explosive mixtures), metal trusses, crane runways, etc.
In residential buildings and structures, it is not allowed to use as grounding conductors water pipes, heating pipes. The smallest permissible dimensions of grounding conductors and grounding elements are shown in the table.
The smallest permissible dimensions of grounding conductors
| Name of the grounding conductor or grounding element | unit of measurement | Available sizes | ||
| In buildings | In outdoor installations | In the ground | ||
| Round steel | mm (diameter) | 5 | >6 | 6 |
| Rectangular steel | mm2 (section) | 24 | 48 | 48 |
| Angle steel | mm (shelf thickness) | 3 | 4 | 4 |
| Steel gas pipe | mm (wall thickness) | 2,5 | 2,5 | 2,5 |
| Steel thin wall pipe | mm (wall thickness) | 1,5 | Not allowed | Not allowed |
The main electrical characteristic of a grounding device is its resistance. It is equal to the sum of the resistances of the ground electrode and grounding conductors. The resistance of the ground electrode is called the resistance to the spreading of electric current.
Electric current, flowing from the ground electrode into the ground, is distributed unevenly in the volume, meeting a certain resistance on its way in the ground. Therefore, they talk about resistance to current spreading from the ground electrode into the ground. For brevity, it is simply called flow resistance.
The spreading resistance of the ground electrode is equal to the ratio of its potential (voltage) at the point of input to the current flowing from the ground electrode to the ground: R \u003d U / I
In electrical installations with voltage up to 1 kV deafly grounded neutral the resistance of the grounding device, to which the neutrals of generators or transformers or the terminals of a single-phase current source are connected, should not exceed at any time of the year 2, 4 and 8 ohms at line voltages, respectively, 660, 380 and 220 V of a three-phase source or 380, 220 and 127 V single-phase current.
This resistance must be ensured taking into account the use natural earthing, as well as ground electrodes for repeated grounding of the neutral wire of the overhead line (VL) up to 1 kV with the number of outgoing lines at least two. But even if this requirement is met, then generators or transformers should still have their own artificial ground electrodes, the resistance of which should be no more than 15, 30 and 60 Ohm at line voltages of 660, 380 and 220 V, respectively, a three-phase source or 380, 220 and 127 V single-phase current.
When the specific electrical resistance ρ of the earth is more than 100 Ohm m, it is allowed to increase the indicated values \u200b\u200bin ρ / 100, but not more than 10 times. At the ends of overhead lines (or branches) with a length of more than 200 m, as well as at the inputs to buildings, the electrical installations of which are subject to grounding, re-grounding is performed, using, first of all, natural, as well as lightning protection grounding conductors.
The total resistance of all these ground electrodes, artificial and natural, for each overhead line should not exceed 5, 10 and 20 ohms at any time of the year at line voltages of 660, 380 and 220 V, respectively, a three-phase source or 380, 220 and 127 V single-phase current. In this case, the resistance of the grounding device of each of the repeated groundings should be no more than 15, 30 and 60 ohms, respectively, at the same voltages. As for the grounding devices of generators and transformers, the values \u200b\u200bof the indicated resistances may be increased by a factor of ρ / 100, but not more than 10 times.
The resistance of the grounding device used for grounding electrical equipment of electrical installations with a voltage of up to 1 kV with an insulated neutral must be no more than 4 ohms. This resistance can be increased to 10 Ohm with a power of generators and transformers of 100 kVA or less; for generators and transformers operating in parallel, a resistance of 10 Ohm is allowed with their total power not exceeding 100 kVA.
The following requirements are imposed on grounding devices in electrical installations with voltages above 1 kV.
Grounding devices for electrical installations with voltages above 1 kV in networks with effectively grounded neutral, intended for grounding electrical equipment, with the exception of supports of overhead power lines (VL), are performed observing the requirements for the resistance of the grounding device or for the touch voltage, as well as for the design and limiting the voltage on the grounding device.
If the grounding device is carried out observing the requirements for its resistance, then the value of the latter at any time of the year should be no more than 0.5 Ohm, including the resistance of natural ground electrodes. In order to equalize electrical potentials between electrical equipment and the ground and to connect this equipment to the ground electrode at a depth of 0.5 ... 0.7 m from the ground surface in the area occupied by the equipment, lay longitudinal and transverse conductors, called horizontal grounding conductors. Conductors are interconnected. The result is a grounding grid. Longitudinal horizontal earthing switches are laid along the axes of electrical equipment from the service side at a distance of 0.8 ... 1.0 m from the foundations or equipment bases. In the event that the sides of the service are facing one another and the distance between the foundations or bases of the rows of equipment does not exceed 3 m, it is allowed to lay one earthing switch for two rows of equipment. In this case, the distance from the longitudinal ground electrode to the foundations or equipment foundations can be increased to 1.5 m. The transverse ground electrodes are laid at the same depth in convenient places between the equipment foundations. To save metal and a more uniform equalization of electrical potentials, the distances between the transverse ground electrodes are taken to increase from the periphery to the center of the grounding grid. In this case, the first and subsequent distances, starting from the periphery, should not exceed 4, respectively; five; 6; 7.5; nine; eleven; 13.5; 16 and 20 m. The size of the cells of the grounding grid adjacent to the points of connection to the grounding conductor of short-circuits and neutrals of power transformers should not be more than 6X6 m2. Along the edge of the territory occupied by the grounding device, horizontal grounding conductors are laid in such a way that together they form a closed loop. If this circuit is located within the external fence of the electrical installation, then at the entrances and entrances to its territory, the potential is leveled by installing two vertical ground electrodes 3 ... 5 m long. The distance between them is chosen equal to the width of the entrance or entrance. By means of welding, these earthing switches are connected to an external horizontal earthing switch.
Implementation of grounding devices for permissible resistance often leads to unnecessary waste of metal and money.
More economical, sometimes several times, grounding devices, performed in compliance with the requirements for the touch voltage.
Such grounding devices must ensure at any time of the year (when ground fault currents drain from them) touch voltage values \u200b\u200bthat do not exceed the standardized ones. When determining them, the sum of the time of action of the main or backup protection and the total opening time of the circuit breaker is taken as the calculated exposure time.
If the permissible values \u200b\u200bof touch voltages are determined at workplaces where, during operational switching, short circuits can occur on structures accessible to touch by the personnel performing the switching, then the specified sum of times should include the duration of the backup protection, and for the rest of the territory - the main one.
For grounding devices made by touch voltage, longitudinal and transverse horizontal ground electrodes are placed, observing only the requirements for limiting touch voltages to standardized values \u200b\u200band convenience of connecting grounding equipment, however, in all cases, the distance between two adjacent longitudinal or transverse horizontal artificial ground electrodes should not exceed 30 m , and the depth of their burial in the ground should be at least 0.3 m. At workplaces, ground electrodes can be laid at a shallower depth, provided that the need for this is confirmed by a calculation, and the ease of maintenance and service life of the ground electrode are not reduced.
To reduce the touch stress, in justified cases, gravel bedding with a thickness of 0.1 ... 0.2 m or an asphalt blind area can be made at workplaces. Resistances of grounding devices made according to permissible touch voltages can be any, but should not exceed the values \u200b\u200bdetermined by permissible voltages on grounding devices and earth fault currents.
The voltages on the grounding devices, made both in resistance and in contact voltage, should not exceed 5 kV when the earth fault current flows from them.
Voltages above 5 kV, but not more than 10 kV are allowed for grounding devices of those electrical installations for which special measures are provided to protect the insulation of outgoing communication and telemechanics cables and to prevent the removal of hazardous potentials outside the electrical installations.
For grounding devices from which the removal of potentials outside the buildings and external fences of the electrical installation is generally excluded, voltages above 10 kV are allowed. Grounding devices of electrical installations with a voltage higher than 1 kV with an insulated neutral are performed in such a way that their resistances, taking into account the resistances of natural ground electrodes at any time of the year, do not exceed the quotient from dividing the coefficient K by the rated earth fault current, expressed in amperes.
When the grounding device is simultaneously used for electrical installations with voltage up to 1 kV, K \u003d 125. In this case, the requirements for the grounding of electrical installations with a voltage of up to 1 kV must also be met.
If the grounding device is used only for electrical installations with voltages above 1 kV, then K \u003d 250. In both cases, the resistance of the grounding device should not exceed 10 ohms.
In soils with a high specific electrical resistance the values \u200b\u200bof resistance of grounding devices are allowed to be increased by a factor of ρ / 500, where ρ is the specific electrical resistance of the earth in ohm-meters. However, this increase should not be more than tenfold.
The total earth-fault current is taken as the rated earth-fault current, provided that there are no capacitive current compensation devices in the network. In networks with compensation of capacitive currents, the rated current for grounding devices to which compensating devices are connected is chosen equal to 125% of the rated current of these devices, and for grounding devices to which no compensation devices are connected, equal to the residual earth fault current, which can be in a given network when the most powerful of the compensating devices or the most branched section of the network is disconnected.
Often the melting current of fuse-links or the tripping current of relay protection against single-phase earth faults is taken as the rated current.
The operating current of the protection against phase-to-phase faults is also taken as the calculated one, provided that this protection ensures the disconnection of earth faults. In all cases, the earth fault current must be at least one and a half times the operation current of the relay protection or three times the rated current of the fuses.
The estimated earth-fault current is determined for that of the possible network circuits in operation, at which it has greatest value... The grounding device of open electrical installations must contain a closed horizontal earthing switch (loop). The depth of its burial in the ground must be at least 0.5 m. The equipment to be grounded is connected to this circuit. In cases where the grounding device is in the ground with a specific electrical resistance of more than 500 Ohm m and its resistance exceeds 10 Ohm, along the rows of equipment from the service side at a distance of 0.8 ... 1.0 m from the foundations or equipment bases, additional horizontal ground electrodes at a depth of at least 0.5 m.
Zeroing.
Zeroing is the connection of metal cases of electrical receivers with the neutral of the supply transformer or generator by means of a neutral wire.
Zeroing should provide reliable automatic disconnection of the network section on which the short circuit occurred. Due to grounding, any short circuit to the case turns into a short circuit and therefore the emergency section is immediately disconnected by an automatic device or fuses.
Zeroing is performed by connecting the body of electrical equipment to the neutral wire of the network. In this case, each housing must be connected to the neutral wire of the network with a separate conductor (Fig. "Zeroing a group of electrical receivers", "a").
It is forbidden to sequentially connect several parts of the electrical installation to the neutral conductor (Fig. "Zeroing a group of electrical receivers", "b").
What is the difference between a neutral conductor and a neutral working conductor?
The neutral conductor is intended only for neutralization. In normal operating mode, the current does not pass through it (Fig. "Zeroing scheme of electrical receivers", "a", "b").
Figure: Zeroing of a group of electrical receivers: a - correct; b - wrong.
Figure: Zeroing scheme for electrical receivers:
Zero working conductor is used to connect single-phase consumers. It cannot be used as a zeroing one (Fig. "Zeroing scheme for electrical receivers", "6").
- a, b - correct zeroing;
- b - wrong
1 - neutral wire of the network; 2 - zero working wire; 3 - neutral wire.
In networks with a solidly grounded neutral, the neutral wire must be grounded, and in several places.
The main grounding of the neutral wire is at the supply substation, repeated - on the power line and at the inputs to the premises.
The earthed consumer equipment usually does not need to be grounded. The neutral wire of the network is reliably grounded and therefore the equipment connected to it is additional grounding does not need.
The need for grounding of earthed equipment, as a rule, is separately specified in the operating instructions or technical description of the equipment.
It should be emphasized that there is no separate ground bus in residential buildings. Therefore, the requirement of manufacturers of household appliances for the mandatory grounding of the enclosures of household appliances is, as a rule, technically impracticable and the enclosures are ground down, which further makes it possible to remove legal liability from manufacturers of household appliances.The spreading resistance of the ground electrode is measured as follows.
This resistance is usually measured by the ammeter and voltmeter method, using portable instruments according to the scheme shown in the figure "Schemes for measuring the resistance to spreading of the ground electrode", "a".
Two auxiliary electrodes are required for measurement. Current T is used in order to pass an electric current through the measured ground electrode, and potential P - to measure the potential of the ground electrode.
The resistance of the ground electrode, measured in the above diagram, is calculated using the well-known formula R \u003d U / I A welding or any other transformer in which the secondary winding is not electrically connected to the primary can be used as a source of measuring current.
Potential and current electrodes are positioned as shown in the figure "Schemes for measuring the resistance to spreading of the ground electrode", "b". In the above diagram, the distances are given for measuring the spreading resistance of the consumer substation ground electrode system, made in the form of a closed loop. When measuring the resistance to spreading of single ground electrodes intended for repeated grounding of the neutral wire of a power line, the indicated distances can be reduced by 2 times.
When measuring the resistance to spreading of the ground electrode with the MS-08 device, it is placed in the immediate vicinity of the connection to the tested ground electrode and one of the circuits shown in figure "c" "Schemes for measuring the resistance to spreading of the ground electrode" or "g" are assembled, which differ from one another only by the fact that in the "g" circuit, it is necessary to subtract the resistance value of the connecting conductor from the meter reading from the ground electrode to terminals I1 and E1. After assembling the circuit, adjust the resistance of the potential circuit. 
Drawing. Schemes for measuring resistance to spreading of a ground electrode:
- a - schematic diagram;
- b - layout of the electrodes;
- c - measurement of the resistance of the ground electrode;
- d - measurement of the total resistance of the ground electrode and the connecting conductor.
For this purpose, the range switch is placed in the "Adjust" position and, by rotating the generator knob at a frequency of about two revolutions per second, using the adjusting rheostat, the instrument arrow is set to the red line.
If it is not possible to set the arrow to the red line, it means that the sum of the resistances of the ground electrode and the potential electrode is more than 1000 Ohm and it is necessary to reduce the resistance of the potential electrode. To do this, they resort to local moistening of the earth with salted water, deeper laying of a potential electrode, or the use of several parallel-connected rods driven into the ground at a distance of 3 ... 4 m from one another.
After adjusting the potential circuit, proceed directly to the measurement. To do this, the range switch is moved to the "XI" position, which corresponds to the measurement range of 10 ... 1000 Ohm, and by rotating the generator handle, the resistance to spreading of the ground electrode is measured. If in this case the arrow falls on the non-working part of the scale (0 ... 10 Ohm), then they switch to a smaller measurement range, move the range switch to the position "X0.1" or "X0.01".
If equipment is reliably grounded (for example, a submersible water pump motor) but not grounded, such equipment creates an increased risk of electric shock. Therefore, it must be zeroed, observing the above listed requirements for the zeroing device.
Additional protective measures for electrical safety in addition to grounding and grounding are widely used devices for equalization of electrical potential and high-speed high-sensitivity residual current devices (RCDs).
To create full-fledged living conditions in a private house, you need to take care of its electrical safety. For this, in addition, even at the design stage, it is necessary to provide for the installation of grounding devices. The installation of the grounding of a private house itself does not present any difficulties, compared, for example, with devices for high-rise buildings.
A grounding circuit for a private house is usually made in the form of pins driven vertically into the ground, connected to each other using horizontal earthing switches and, using a conductor connected to an electrical panel.
Vertical ground electrodes, as a rule, are made of steel corners with dimensions of 5 × 5x0.5 cm. Horizontal ground electrodes can be made of strip steel with dimensions of 4 × 40 mm. The conductor is most often made of a round steel bar with a cross section of 8-10 mm2.
Vertical grounding conductors and conductors must not be made of fittings. This is due to the fact that the reinforcement has a hardened outer layer, as a result of which the normal distribution of the current over its cross section is disrupted and the oxidation processes proceed differently (the material becomes covered with rust faster).
Structurally, it is customary to make the ground loop in the form of an equilateral triangle. For this purpose, appropriate markings are made in the yard of the house. The very same grounding loop, the rules are recommended to be located no further than 1 meter from the foundation of the building.
After the marking is completed, a trench about a meter deep and 50-70 cm wide is pulled out along the perimeter. This trench is intended for laying horizontal ground electrodes.
Further, along the vertices of the triangle, you should drive in vertical grounding rods (to a depth of 2-3 m). The pins can be driven in with an ordinary sledgehammer, which is not at all difficult when used as angle pins. In order to facilitate this process, the corners at the ends can be sharpened, then they will more easily enter the ground. You can also dig or drill small wells about one and a half meters deep, then you will have to drive into a smaller layer of soil.
After completing all the preliminary work, choosing a place, marking and digging a trench, you can proceed to the installation of the ground loop itself. On the tops of the trench, corners are driven into the ground, but not completely, but so that 200-250 mm of a corner protrudes from the trench.
After the vertical parts of the circuit have been driven in, they must be connected to each other using horizontal ground electrodes, creating a closed circuit. Typically, this is done by welding, welding the strips to the overhanging corners. It is necessary to connect the corners to the strip only by welding; bolted connections for this are unacceptable.
After assembling the grounding loop itself, it must be connected to the electrical panel. To do this, you must again use welding. The grounding conductor (steel wire with a diameter of 8-10 mm) should be welded to the circuit, and then lay it along the trench to the shield. At the end of the wire, from the side of the shield, an M6 (M8) bolt is welded, designed to fasten the grounding one.
In the absence of steel wire, it is permissible to use a steel strip as a grounding conductor, such as was used in the manufacture of a horizontal grounding electrode.
Under traditional grounding means an earthing switch made of black steel without a protective coating.
We classify artificial grounding conductors used in traditional grounding according to various parameters.
To begin with, let us recall that ground electrodes can be horizontal and vertical.
A steel equal-flange angle and a circle are most often used as a vertical ground electrode, and a strip or a bar (circle, reinforcement) is used as a horizontal one.
Regulations
The minimum dimensions of ground electrodes are standardized by the rules for electrical installations (Tab. 1.7.4.), And technical circular No. 11/2006 (Tab. 1).
Although this circular is a recommendation for most organizations, it has been increasingly referenced by oversight structures in recent times. We advise you to use it too, since the requirements of the circular are more suitable for modern electrical installations.
Corners
Corners for grounding usually have dimensions 45x45x5, 50x50x5, 63x63x5 and 63x63x6. In order to speed up the installation procedure, the corners are sharpened at the end on one side at an angle of 30 °.
Earthing switch corner
Circle and fittings
Steel circle most often diameters? 18 or? 20. You can also use construction fittings.
Earthing switch circle and fittings
Ground strip
For a horizontal earthing switch, they often use strip with a length and width of 40x5 mm and 50x5 mm, as well a circle ? 10 mm.
Earthing switches strip and circle
Grounding installation
Recall that the steel of the ground electrode must not be painted. Only welding spots can be painted. When installing in soil with an aggressive environment, the cross-sectional area of \u200b\u200bthe grounding conductors should be increased, for example, not a 45x45x5 corner, but a circle with a diameter of O20.
The installation process of this kind of ground electrode system is simple to understand, but tedious to perform, especially when it is necessary to achieve a sufficiently low resistance of 2-4 ohms.
Digging a trench
First you need to mark and dig a trench 70-80 cm deep under a horizontal ground electrode. If the access of equipment is possible, then you can save on physical labor. For digging trenches, it is optimal to use a backhoe loader.
Driving corners into the ground
After the trench has been dug, you can start installing the corners. There are many methods and devices for immersing corners in the ground, but most often two of them are used. The first is to hammer the corners with a sledgehammer. This method is suitable if there are not many corners.
The second method is faster and simpler, the corners are pressed by the excavator bucket. This method is the most optimal, but equipment rental is not cheap.
If a long corner is used, then it is recommended to make a hole in the trench beforehand, otherwise it will be difficult to hammer the corner.
The distance between vertical ground electrodes must be at least their length.
Laying the ground electrode
We lay the horizontal ground electrode at the bottom of the trench and weld it with vertical ground electrodes.
Don't forget to miss welds bituminous varnish or paint to prevent corrosion.
Drawing up an act of work
Before backfilling the trench, it is necessary to draw up a passport (act) for hidden works for the installation of the memory, which is signed by the representative of the customer and the installation organization.
