There were those times when the developers did not hear about the grounding circuit. Now they know perfectly well what to think about their safety, the protection of numerous equipment, in the acquisition of which there were considerable money. In order for the grounding contour to perform its functions as efficiently, it needs to be correctly calculated. All about what will be discussed below, just and devoted to the solution of this issue.

Source for calculating ground loop

Grounding is intended to carry out the main purpose: reduce tension to such an extent that when contacting electrical appliances, it has not constituted threats for dwelling. The configuration and resistance of the grounding circuit of the house determine:

• the length and number of electrodes;
• the range on which they are located relative to each other. Measuring the electrode in length and taking 2.2 parts from the result, we get a distance of which is not allowed;
• depth installation of electrodes, and it is regulated by 70 cm and no less;
• electrically conductive properties of land in this particular area.

Therefore, these source will participate in the calculation.

Material required for ground contour device

Before starting the calculation of the grounding contour, it is necessary to consider from what it will be created and then perform the calculation for the selected material. Ground contour are arranged from:

• pipes with highs of 0.35 cm;
• armature or circle. Suitable rolling with a diameter of at least 1.6 cm;
• metal corner with shelves not thinner 0.4 cm.

The link between the electrodes is the steel strip with dimensions of 0.4x1.2 cm. Grounding electrodes are placed:

• in a row;
• triangle;
• like a square or other geometric shape.

What should we have at the end of the calculation of the resistance of the ground loop

Execution of the calculation of the grounding circuit is not a question of theory, the fruit of our efforts will be the answer to quite practical questions:

• how many grounding rods will be placed in the circuit mounted by us;
• for a strip connecting them, we will find the length.

The main parameter when calculating the ground loop is its resistance. In PUE, there are such instructions on this:

• for power grid with a voltage of 220 V - 8 ohms;
• with a voltage of 380 V - 4 ohms.

The formula for which we will calculate, has the form: R \u003d R0 / ηV * N:

• R0 here refers to the resistance of a single electrode;
• R is the resistance as a whole;
• ηv - the coefficient characterizing the demand of the electrical circuit, in other words - the utilization rate coefficient;
• N - the number of electrodes in the grounding circuit.

But the formula for which we will define the resistance of one component of the electrical circuit:

where:

• ρEKV - denotes the resistivity of the soil is equivalent. Measured in OM * m. You can determine it from the table. It is suitable if the soil is homogeneous;

• L is the length of the grounding rod. The greater ρecv, the greater L. If the soil is such that the electrodes whose length we calculated, it will not be included in it, then the exit in increasing their quantity;
• d - electrode diameter;
• T - the length of the gap of the earth-middle of the electrode.

At the same time, the last 3 values \u200b\u200btake in m. If the soil has an inhomogeneous structure and consists of 2 layers, then you will have to make a calculation by the formula:

In this formula: ψ - the coefficient of seasonal climatic; The resistivity 1 and 2 of the layer of the Earth is denoted by ρ1 and ρ2, respectively; The symbol η indicates the thickness of 1 layer; T - the depth of the trench, which must be pulled out under the electrode. I will find the value by using the table:

The grounding circuit device under these circumstances is performed when the rods are lowering for the entire layer and partially involved the second.

Calculate the desired number of rods

In order to find out how many rods we need, we define from the lower RN table below, i.e. Resistance normalized:

If a parallel element is not taken into account, then the number of rods is determined as follows:

• we take resistance r0;
• multiply it on the climatic seasonal coefficient ψ;
• we divide the work on the normalized resistance of RN.

n0 \u003d R0 / ψ x Rn. Now we will pay attention to the parallel earthing. This is how the formula looks like to determine its resistance:

For calculations, data on the length of the rod will be required. For earthing people located in a row and contour, different formulas. In 1 case, LG will define like this:

• from previously found N0, take 1;
• multiply obtained on a - gap between the rods.

In 2 case LG \u003d a. Now we have all the data to determine the resistance of the rods located perpendicular to the Earth - RV, given the horizontal earthingers. For this:

• multiply the resistance of the horizontal earthinger Rg to the normalized resistance RN;
• then we find the difference between RG and RN;
• multiply the first result on the second.

It remains to substitute the received in the formula and find the total number of grounds:

here:

• ɳB - use ratio. It affects the span between the electrodes. In case the pipes are chosen in the same line and combined with a strip as ground electrodes, the coefficient value can be selected from the table;

• n - the number of grounding electrodes;
• if the result is the number of fractional, then the result is rounded to the side greater.

Measurement of grounding contour

To fully make sure in impeccable grounding operation, it is necessary to measure the grounding circuit, for which there are specially intended for this instruments. Timely measurements will help:

• exploit electrical appliances without fear of electric shock;
• it is timely to identify weak parameters and characteristics, because the characteristics of the soil may change or suddenly rusts some element.

The earth contour, the scheme of which is shown below, is ideal for a private house.

Experience shows that for the average mansion, it is enough 3 electrodes, which in terms create an equifiable triangle with parties 120 cm.

On the grounding and its components available to the language, you will learn from this video: