Ground loop - device, calculation and installation of the grounding system for a country house

By Admin | Garden And Buildings / Communication
04 May 2016

Thanks to technology mnogomoschnye electrical appliances flooded our homes.Even hard to imagine life without a refrigerator, washing machine, microwave oven, induction cooker - after all, we use every day.Do not forget that electric appliances are dangerous for us in case of violation of their isolation.Therefore, it is imperative to equip ground loop for the entire house, thus having secured himself and devices from the breakdown in the body.

Content

What is the ground loop ↑

shall declaretechnically dry tongue, grounding means electrically connected to the earth (ground) live elements of electrical installations, performed deliberately.The data of the appliances are not live in a normal state, but may be under him.The reason may be a violation of the insulation as well.

To explain more simple and accessible language, have to remember high-school physics.As we rememb

er, the current tends to flow in the direction of least resistance.If the insulation of live parts broken equipment, the current will be looking for a place where the resistance is the lowest.So there is a breakdown in the body of the appliance.In other words, metal body will be under stress.In addition, it may disrupt the device itself, or even break it, if you are currently a person touches a surface of the body, it will get an electric shock.

Circuit ground is needed in order to distribute the current between a man and a grounding device is inversely proportional to their resistance.Considering that the resistance of the human body many times will exceed the resistance of the grounding circuit, have flowed through the current capacity, and the rest goes into the ground.We have come to a very important point: performing ground loop with your hands, you must make it so that its resistance was minimally acceptable.

Device ground loop ↑

It looks like a ground loop
Ground loop is performed using steel rods to hammer on the depth and bars, sodinyayuschih their

The most common grounding is done via metal rods - electrodes buried in the ground and connected to each other at the top of the stripor bar.This structure houses adjoining the flap is connected to a cable or a metal strip.

The depth of the electrodes depends on the saturation of soil water.The above are ground water, the lower the required depth.

distance from the house should be at least 1 m but not more than 10 m.

Dimensions of earth
minimum dimensions fittings used for the installation of grounding devices

Circuit ground private home run by a rod, as which can act steelCorner fittings with smooth structure, pipe, girders.The sectional area of ​​the electrodes must be greater than 1.5 cm2, and the shape should be convenient for driving into the ground.

rods are arranged in series or in the form of geometric shapes: triangle, square, rectangle.It depends on the design and ease of installation space that can be used.It is also possible hardware loop around the perimeter of the building.But the most popular continues to be a triangular ground loop.The tops of the figures hammered electrodes, which are connected by a steel band.

Important!Ground loop must necessarily be located below the frost line.

other words, grounding can be done using the material at hand.But it is possible to buy a ready kit for the ground loop arrangement.It consists of rods - the electrodes of copper plated steel, 1 m long, are joined a threaded connection.These kits are not cheap, but make it much easier to use and durable.

How to make a payment ↑

course, grounding can be made empirically.For example, to determine the depth of the water to retreat from the house at the optimal distance and build a triangular outline.Cook the electrodes to each other and measure the resistance of the resulting structure.If it is too large, bury more additional electrodes, attach them to the previous one and take measurements again.And so long as the measurement result will not meet the requirements.

Experts also strongly recommend that before you make a ground loop, make all the necessary calculations.To determine the number of vertical earth electrodes - electrodes, which is required, and the length of the connecting bars, depending on the resistance of the soil.

For starters need to determine the resistance of the vertical grounding - electrode.

The resistance value of the vertical grounding
Formula 1. Resistance of vertical earthing

Where,

R 0 - one electrode resistance, Ohm;

ρekv - the equivalent soil resistivity, Ohm * m;

L - electrode length, m;

d - electrode diameter, mm;

T - the distance from the center electrode to the ground surface, m.

The values ​​of soil resistivity
Table 1. The resistivity of soil

Seasonal climatic coefficient of resistance of soil
Table 2. The value of seasonal climatic resistance coefficient soil

value of earth resistance can be takenfrom the table, but if the ground is non-uniform, then

Ekvivaletnoe soil resistivity, if inhomogeneous
Formula 2. Ekvivaletnoe resistivity of inhomogeneous soil

Where,

Ψ - seasonal climatic factor;

ρ1, ρ2 - soil resistivity (1 - the upper layer 2 - the bottom layer), Ohm * m;

H - the thickness of the upper layer of soil, m;

t - the depth to which the electrode is clogged, m (trench depth);

Excluding horizontal earth electrode resistance, the number of electrodes can be found by the formula:

The formula of finding the number of electrodes
Formula 3. The number of electrodes without the horizontal resistance earthing

Where,

n0 - the number of electrodes;

R n - normable grounding resistance based on the PTEEP.

Таблица соответствия "Наибольшее допустимое значение сопротивления заземляющих устройств (ПТЭЭП)"
Table 3. The highest permissible value of resistance of grounding devices (PTEEP)

determines the resistance of the current horizontal earthing formula:

The formula for finding the current horizontal resistance grounding
Formula 4. Resistance to current spreading horizontal earthing

Where,

L Mr. - the length of the grounding;

b - the width of the grounding;

ψ - seasonal coefficient of horizontal earth electrode;

ɳG - demand factor of horizontal earth electrodes.

length earthing is so:

The formula for finding the length of the horizontal earthing
Formula 5. The length of the horizontal earthing

Where,

a - the distance between the electrodes.

Resistance vertical electrodes based on a horizontal earth electrode:

Formula finding resistance vertical earthing
Formula 6. Resistance vertical earth electrodes - electrodes based on a horizontal earth electrode resistance

The total number of vertical earth electrodes - electrodes equals:

The total number of electrodes
Formula 7. The final number of vertical earthing

Where,

ɳv - demand factor vertical earthing.

The value of the coefficients of earth use
Table 4. The utilization of earth

index called "utilization rate" shows the effect of each other, depending on the current location of the vertical electrodes.If the electrodes are connected in parallel, the currents flowing on them affect each other.The shorter the distance between the electrodes, the total resistance of the circuit more.

If the number of earth, resulting in the last formula is not an integer, round it up to the whole in a big way.

Ground loop: the scheme ↑

After all the calculations are made, choose a convenient location for the ground loop.Determine which figure will be placed electrodes.Then draw a ground loop circuit according to the type of materials used.Be sure to specify that used for the electrodes and the connecting band, their length and diameter, depth, location.

Driving ground loop
Ground loop: the scheme on the passport (outside the building) - the example

Driving ground loop
Ground loop: the scheme on the passport (inside the building) - the example

All this we will need not only for ease of installation and the futurebut in order to get a passport ground loop.When the installation work will be completed and measured loop resistance, energy management staff who need to be invited, will be given Sight and all necessary documentation to the ground loop.Of course, in this case, if done correctly.

Construction ground loop ↑

Installation ground loop is better to start in the warm season.So it will be easier to excavate and measure the resistance of the ground.Then it will be seen more accurately, the depth at which the groundwater occur.

Consider the case of ground loop arrangement in the form of a triangle:

How to make a ground loop in a private house
arrangement for grounding circuit is necessary dig a trench to a depth of soil freezing
  1. place we have chosen.So we dig a trench depth of 0.7 m to 1 m (below the frost line), a width of 0.5 - 0.7 m. The lines should form a triangle with a side length of which has been determined in the course of calculations.
  2. From one of the angles of a triangle dig a trench in the direction of the power panel.
  3. the vertices of the triangle trying to drive grounding - electrode.What exactly will be used for this purpose, need to be addressed at the stage of settlement.Suppose as an example it will steel bracket 50 * 50 mm.If the density of the soil does not allow a goal rods have to drill wells.
  4. bury the rods so that they protrude above the ground.If we still had to drill wells, install them in the corners and covered with soil, mixed with salt.Take
  5. steel strip 40 * 5 mm and welded to the electrodes, forming a contour in the shape of a triangle.Then, one of them conducting strip to the power cabinet.
  6. strip fixed to the ground wire or power board using a screw diameter of 10 mm.When this bolt is welded to the required bandwidth.
  7. At this point, check the ground loop resistance ohmmeter.This device is cheap, buy it does not make sense.It is better to invite employees of energy management that they took measurements and completed passport ground loop.Resistance index should be less than desired.If not, then it is necessary to drive the additional electrodes.
  8. If the resistance was sufficient fall asleep trench uniform ground without construction waste and rubble.

Important!During further operation in the abnormally dry weather is desirable to irrigate the ground loop from the hose with water to reduce its resistance.

All work related to the calculation and installation of the ground loop can be left to professionals who have more experience.This can save you time and hassle.But if you tend to do things with their hands, go for it.Your creation will serve to protect you and your family.