In theory, the diameter of the conductors should correspond to the declared parameters. For example, if it is indicated on the marking that the cable is 3 x 2.5, then the cross section of the conductors must be exactly 2.5 mm2. In fact, it turns out that the real size can differ by 20-30%, and sometimes more. What does it threaten? Overheating or melting of insulation with all the ensuing consequences. Therefore, before buying, it is advisable to find out the size of the wire in order to determine its cross section. How exactly to calculate the cross section of the wire in diameter and we will find out further.

How and with what to measure the diameter of the wire (wire)

To measure the diameter of the wire, a caliper or micrometer of any type (mechanical or electronic) is suitable. It is easier to work with electronic ones, but not everyone has them. It is necessary to measure the core itself without insulation, therefore first move it away or remove a small piece. This can be done if the seller allows. If not, buy a small piece to test and take measurements on it. On a conductor stripped of insulation, measure the diameter, after which you can determine the actual cross-section of the wire according to the dimensions found.

Wire diameter measurements with a micrometer are more accurate than mechanical calipers

Which measuring device is better in this case? If we talk about mechanical models, then a micrometer. It has higher measurement accuracy. If we talk about electronic options, then for our purposes they both give quite reliable results.

If you don't have a caliper or micrometer, take a screwdriver and a ruler with you. You will have to strip a pretty decent piece of the conductor, so this time you are unlikely to do without buying a test sample. So, remove the insulation from a piece of wire 5-10 cm. Wind the wire around the cylindrical part of the screwdriver. The coils are laid close to each other, without a gap. All turns must be full, that is, the "tails" of the wire must stick out in one direction - up or down, for example.

Determining the wire diameter using a ruler

The number of turns is not important - about 10. It can be more or less, it's just easier to divide by 10. You count the turns, then apply the resulting winding to the ruler, aligning the beginning of the first turn with the zero mark (as in the photo). Measure the length of the section occupied by the wire, then divide it by the number of turns. Get the wire diameter. It's that simple.

For example, let's calculate the size of the wire shown in the photo above. The number of turns in this case is 11, they occupy 7.5 mm. We divide 7.5 by 11, we get 0.68 mm. This will be the diameter of this wire. Next, you can search for the cross section of this conductor.

We are looking for a wire cross-section by diameter: formula

The wires in the cable have cross section circle shape. Therefore, in the calculations we use the formula for the area of ​​a circle. It can be found using either the radius (half of the measured diameter) or the diameter (see formula).

Determine the cross section of the wire by diameter: formula

For example, let's calculate the cross-sectional area of ​​​​the conductor (wire) according to the size calculated earlier: 0.68 mm. Let's use the radius formula first. First we find the radius: we divide the diameter by two. 0.68 mm / 2 = 0.34 mm. Next, we substitute this number into the formula

S = π * R2 = 3.14 * 0.342 = 0.36 mm2

It is necessary to count as follows: first we square 0.34, then we multiply the resulting value by 3.14. We got the cross section of this wire 0.36 square millimeters. This is a very thin wire that is not used in power networks.

Let's calculate the cable cross-section by diameter using the second part of the formula. It should be exactly the same value. The difference may be in thousandths due to different rounding.

S \u003d π / 4 * D2 \u003d 3.14 / 4 * 0.682 \u003d 0.785 * 0.4624 \u003d 0.36 mm2

In this case, we divide the number 3.14 by four, then square the diameter, multiply the two resulting numbers. We get a similar value, as it should be. Now you know how to find out the cable cross-section by diameter. Whichever of these formulas is more convenient for you, use that one. No difference.

Correspondence table for wire diameters and their cross-sectional area

It is not always desirable or possible to carry out calculations in a store or in the market. In order not to waste time on calculations or not to make a mistake, you can use the table of correspondence of diameters and cross-sections of wires, which contains the most common (standard) sizes. You can write it down, print it out and take it with you.

Conductor diameter	Conductor cross section
0.8mm	0.5 mm2
0.98 mm	0.75 mm2
1.13mm	1 mm2
1.38mm	1.5 mm2
1.6mm	2.0 mm2
1.78mm	2.5 mm2
2.26mm	4.0 mm2
2.76 mm	6.0 mm2
3.57 mm	10.0 mm2
4.51 mm	16.0 mm2
5.64 mm	25.0 mm2

How to work with this table? As a rule, the cables have a marking or a tag on which its parameters are indicated. It indicates the cable marking, the number of cores and their cross section. For example, VVNG 2x4. We are interested in the parameters of the core, and these are the numbers that come after the “x” sign. In this case, it is stated that there are two conductors having a cross section of 4 mm2. So we will check whether this information is true.

To check, measure the diameter using any of the methods described, then refer to the table. It states that with such a cross section of four square millimeters, the wire size should be 2.26 mm. If your measurements are the same or very close (there is a measurement error, since the devices are not ideal), everything is fine, you can buy this cable.

The stated dimensions do not always correspond to the real ones.

But much more often, the actual diameter of the conductors is much less than the declared one. Then you have two ways: look for a wire from another manufacturer or take a larger section. Of course, you will have to overpay for it, but the first option will require a fairly long period of time, and it’s not a fact that you will be able to find a cable that meets GOST.

The second option would require more money, since the price significantly depends on the declared section. Although, not a fact - a good cable, made according to all standards, can cost even more. This is understandable - the cost of copper, and, often, for insulation, subject to technology and standards, is much higher. Therefore, manufacturers are cunning, reducing the diameter of the wires - in order to reduce the price. But such savings can turn into disaster. So be sure to take measurements before buying. Even trusted suppliers.

And one more thing: inspect and feel the insulation. It should be thick, solid, have the same thickness. If, in addition to changing the diameter, there are also problems with insulation, look for a cable from another manufacturer. In general, it is desirable to find products that meet the requirements of GOST, and not made according to TU. In this case, there is hope that the cable or wire will last a long time and without problems. This is not easy to do today, but if you are wiring a house or connecting electricity from a pole, quality is very important. That's why it's probably worth looking into.

How to determine the cross section of a stranded wire

Sometimes stranded conductors are used - consisting of many identical thin wires. How to calculate the wire cross-section by diameter in this case? Yes, exactly the same. Take measurements / calculations for one wire, count their number in a bundle, then multiply by this number. So you will find out the cross-sectional area of ​​\u200b\u200ba stranded wire.

The cross section of a stranded wire is considered similar.

In the modern technological world, electricity has practically become on the same level in importance as water and air. It is applied in almost any sphere of human activity. There was such a thing as electricity back in 1600, before that we knew about electricity no more than the ancient Greeks. But over time, it began to spread more widely, and only in 1920 did it begin to displace kerosene lamps from street lighting. Since then, the electric current began to spread rapidly, and now it is even in the most remote village, at least illuminating the house and for telephone communications.

Electricity itself is a stream of directed charges moving along a conductor. A conductor is a substance capable of passing these electric charges through itself, but each conductor there is resistance(except for the so-called superconductors, the resistance of superconductors is zero, this state is achievable by lowering the temperature to -273.4 degrees Celsius).

But, of course, there are still no superconductors in everyday life, and it will not be soon to appear on an industrial scale. In everyday life, as a rule, current is passed through wires, and it is mainly used as a core copper or aluminum wires. Copper and aluminum are popular primarily due to their conductive properties, which are inverse to electrical resistance, and also because they are cheap compared to, for example, gold or silver.

How to understand the sections of copper and aluminum cables for wiring?

This article is intended to teach you how to calculate wire size. It's like the more water you want to supply, the larger diameter pipe you need. So here, the more consumption electric current, the larger should be the cross section of cables and wires. I will briefly describe what it is: if you bite a cable or wire and look at it from the end, then you will just see its cross section, that is, the thickness of the wire, which determines the power that this wire is able to pass, warming up to an acceptable temperature.

In order to correctly select the cross section of the power wire, we take into account the maximum value of the consumed current load. You can determine the values ​​\u200b\u200bof currents, knowing the nameplate power of the consumer, it is determined by the following formula: I \u003d P / 220, where P is the power of the current consumer, and 220 is the number of volts in your outlet. Accordingly, if the outlet is 110 or 380 volts, then we substitute this value.

It is important to know that the calculation of the value for single-phase and three-phase networks is different. In order to find out how many phases of the network you need, you need to calculate the total amount of current consumption in your home. Here is an example of an average set of equipment that you might have at home.

A simple example of calculating the cable cross-section for current consumption, now we will calculate the sum of the power of connected electrical appliances. The main consumers in the average apartment are the following devices:

• TV - 160 W
• Refrigerator - 300 W
• Lighting - 500 W
• Personal computer - 550 W
• Vacuum cleaner - 600 W
• Microwave oven - 700 W
• Electric kettle - 1150 W
• Iron - 1750 W
• Boiler (water heater) - 1950 W
• Washing machine - 2650 W
• Total 10310 W = 10.3 kW.

When we know the total consumption of electricity, we can use the formula to calculate the cross section of the wire, for the normal functioning of the wiring. It is important to remember that for single-phase and three-phase networks, the formulas will be different.

Calculation of the wire cross section for a network with one phase (single-phase)

The calculation of the wire cross section is carried out using the following formula:

I = (P × K and) / (U × cos(φ))

I- current strength;

• P- power of all energy consumers in total
• K and- coefficient of simultaneity, as a rule, the generally accepted value of 0.75 is taken for calculations
• U- phase voltage, which is 220V but can range from 210V to 240V.
• cos(φ)- for household single-phase appliances, this value is steel, and equals 1.

When we have found the current consumption power according to the formula, we can start choosing a cable, which suits us in terms of power. Or rather, its cross-sectional area. Below is a special table in which data is provided, which compares the amount of current, cable cross-section and power consumption.

Data may vary for wires made of different metals. Today, for residential applications, as a rule, copper, rigid cable is used. Aluminum cable is practically not used. But still, in many old houses, aluminum cable is still present.

Table of estimated cable power by current. The choice of the copper cable section is made according to the following parameters:

We also give a table for calculating the current consumption of an aluminum cable:

If the power value turned out to be the average between the two indicators, then it is necessary to select the value of the wire cross section in the larger direction. Since the power reserve must be present.

Calculation of the wire cross section of a network with three phases (three-phase)

And now we will analyze the formula for calculating the wire cross section for three-phase networks.

To calculate the cross section of the supply cable, we use the following formula:

I = P / (√3 × U × cos(φ))

• I- current strength, according to which the cross-sectional area of ​​\u200b\u200bthe cable is selected
• U- phase voltage, 220V
• Cos φ - phase angle
• P- shows the total consumption of all electrical appliances

Cos φ- in the above formula is extremely important, since it personally affects the current strength. It differs for different equipment, this parameter can most often be found in technical documentation, or the corresponding marking on the case.

The total power is very simple, we sum up the value of all power indicators, and use the resulting number in the calculations.

A distinctive feature in a three-phase network is that a thinner wire is able to withstand a greater load. The wire section we need is selected according to the table below.

The calculation of the wire cross section for the current consumed, used in a three-phase network, is used using such a value as √3 . This value is needed to simplify the appearance of the formula itself:

U linear = √3 × U phase

In this way, if necessary, the product of the root and the phase voltage is replaced by a linear voltage. This value is equal to 380V (U linear = 380V).

The concept of continuous current

Also one at least important point when choosing a cable for a three-phase and single-phase network, it is necessary to take into account such a concept that sounds like a permissible continuous current. This parameter shows us the amount of current in the cable that the wire can withstand for an unlimited amount of time. You can determine the ego in a special table. Also for aluminum and copper conductors, they differ significantly.

In the case when this parameter exceeds the permissible values, the conductor overheats. The heating temperature is inversely proportional to the current strength.

Temperatures may rise in some areas not only due to incorrectly selected wire cross-section, but also with poor contact. For example, in the place of twisting of wires. This often happens at the point of contact between copper and aluminum cables. In this regard, the surface of the metals undergoes oxidation, becoming covered with an oxide film, which greatly worsens the contact. In such a place, the cable will heat up above the permissible temperature.

When we have done all the calculations and checked the data from the tables, you can safely go to a specialized store and buy the cables you need to lay the network at home or in the country. Your main advantage over, for example, your neighbor will be that you fully understand this issue with the help of our article, and save a lot of money by not overpaying for what the store wanted to sell you. Yes, and knowing how to calculate the current cross section for copper or aluminum wires will never be superfluous, and we are sure that the knowledge gained from us will be useful many times on your life path.

How to determine the cross section of the cable and wire?

At home, we often use portable extension cords for temporary (or even permanent) connection of household appliances: electric heater, air conditioner, iron, etc. with various, sometimes significant, consumption currents.
The cable and wires for this extension cord are usually chosen according to the principle - what came to hand (from economic old stocks), which does not always correspond to the necessary electrical parameters.
It is necessary to find out at least the cross section of this wire or cable, is it suitable for this load?

How to determine the cross section of an unknown wire - cable?
To do this, it is necessary to open the sheath of the core of the wire - cable.
If the wire is single-core, then you need to measure its diameter and according to the formula
S = π d²/4 or S = 0.8 d² where:
S is the cross-sectional area of ​​the wire in sq. mm;
pi - 3.14;
d is the wire diameter in mm.
determine its cross section.

For example: wire diameter d \u003d 1.5 mm., Then its cross section S = 0.8 d² = 0.8 1.5 1.5 = 1.8 mm.sq.

If the wire is stranded, then it is necessary to fluff it, count the number of veins in the bundle. Determine the diameter of one strand, calculate its cross-sectional area s, then determine the cross-sectional area of ​​the entire wire by adding the areas of all the strands.

For example: the number of veins in the bundle is 37 pieces; diameter of each vein d = 0.3 mm.
Determine the cross-sectional area of ​​​​one vein.
s \u003d 0.8 d² \u003d 0.8 0.3 0.3 \u003d 0.072 mm.kv.
Cross-sectional area of ​​the entire stranded wire
S \u003d 37 s \u003d 37 0.072 \u003d 2.66 mm.kv.

The diameter of the wire strand is measured with a caliper or micrometer. If such measuring tools are not available, then the diameter of the wire strand can be determined using an ordinary ruler.
We wind the measured vein on a pencil or rod 10 - 15 turns (the more, the more accurate the measurement), tightly turn to turn. With a ruler, measure the total winding distance in millimeters. Then we divide this size by the number of turns. Get the diameter of the vein in mm.

The cross section of the wiring depends on the material and the load. Aluminum is now rarely used. Only copper and a composite material, aluminum copper, remain, from which electrical wire is produced. The size of the cross section is not always known for the following reasons: there are no markings, the core diameter does not correspond to that specified in the accompanying documents.

What are the types of cables and wires

wire and cable

To designate a conductor, 2 concepts are often used: wire and cable. They are often confused, although they have some differences.

The wire is a single conductor and is divided into 2 groups: a solid wire with or without insulation, a flexible wire woven from thin wires.

The cable consists of a group of cores enclosed in separate and general insulation. The cores can be solid (VVG, VVGng, NYM) or woven (PVS).

Conductor materials

The amount of energy transferred depends primarily on the material of the conductor. It can be one of the following non-ferrous metals:

1. Copper - low electrical resistance; high strength and elasticity; easy to weld and solder; low contact resistance on the contacts; high price.
2. Aluminum is a lightweight and cheap material; electrical conductivity is 1.7 times lower than that of copper; easily deformed; high transition resistance of oxidized surfaces; welding is possible in an inert gas environment, and special solders and fluxes are required for soldering.
3. Aluminum-copper - a composite with an aluminum base and a copper coating; conductivity is slightly lower than that of copper; cable and wire are lighter; inexpensive material.

Methods for determining the cross-sectional area of ​​\u200b\u200bwires and cores are not much different. First of all, you need to measure the diameter of the conductors. They provide reliable insulation that must be removed. There are 3 ways to do this.

Measuring instruments

Micrometers and calipers are used as instruments. Usually mechanical devices are used, although there are also electronic ones with a digital display. One of these devices will always be found among the tools of the home owner.

The most commonly used caliper is suitable for measuring wires in an existing network, for example, in a switchboard or socket. The cross-sectional area of ​​the conductor is as follows:

S Kr \u003d 3.14D 2 / 4,

where D is the diameter of the wire.

The diameter is measured at least three times, when the cable is rotated by 120 0. The average value is taken as the result.

Measuring the wire diameter with a caliper

In the absence of devices, the diameter of the wire is determined using a ruler. To do this, the core is cleaned of insulation and wound with tight turns around the pencil (at least 15 turns). Then measure the winding length and divide it by the number of turns. The coils must be evenly laid and adjacent to each other without gaps.

Measuring wire diameter with a ruler

Take several measurements with different parties. Then the result will be more accurate. Strands of large thickness cannot be wound onto a pencil, and in the store a check can be made only after the purchase of the product. The size of the section can be determined by the formula or resort to the table.

1. Aluminum is easy to distinguish from copper, which has a characteristic rich color. Instead, there may be an alloy of metals, which is easy to determine by appearance.
2. If there is any doubt about the material and the statute of limitations of the conductor, a larger section is taken. The correctness of the choice is then checked by heating the wire at rated load. If it does not heat up, then the calculation is correct.
3. The cable contains several conductors. To select the required section, the diameter is determined individually for each of them, and then the required amount is combined together to obtain the desired area:

S total \u003d S 1 + S 2 + ... + S n,

S total - total cross section,

S 1, S 1, S n - cross-sections of individual conductors.

stranded wire

The PVA cable for connecting power tools and electrical appliances is made flexible, since all cores are multi-wire. Measuring the bundle diameter at the same time will give an incorrect result because there are air gaps inside. The correct calculation principle is the same as for the cable. The core should be fluffed, count how many wires are in it, and then measure the diameter of one of them. Knowing their total number in the core, you can calculate the total cross section using the previous formula. Only measurements are best done with a micrometer. It is more convenient to use it, since the caliper easily pushes through thin wires.

segment cable

A cable with a cross section of up to 10 mm 2 is always made round. They can always provide the household needs of an apartment or a private house. With a larger cable cross section, the input cores from the external power supply are made segmented, which are difficult to calculate. It is convenient to determine the cross-sectional area when there is a ready-made calculation table. To do this, you must first measure the height and width of the segment.

Table for calculating the area of ​​the cable core segment

Cable		Sectional area of ​​the segment, mm2
		35	50	70	95	120	150	185	240
Three-core sector single-wire, 6(10) kV	in	5.5	6.4	7.6	9	10.1	11.3	12.5	14.4
	sh	9.2	10.5	12.5	15	16.6	18.4	20.7	23.8
Three-core sector multiwire, 6(10) kV	in	6	7	9	10	11	12	13.2	15.2
	sh	10	12	14	16	18	20	22	25
Four-core sector single-wire, up to 1 kV	in	-	7	8.2	9.6	10.8	12	13.2	-
	sh	-	10	12	14.1	16	18	18	-

Calculation of the cross section of the conductors

By power

The calculation method is preferred, since the documentation for the devices and their labels indicate the amount of average and maximum power consumption. For wiring, it is important to know the limit value. A washing machine can consume from tens of watts when rinsing up to 2.5 kW during the heating process. In addition, there can be several consumers on one core. The total power is determined by summing up all the maximum values.

The average load in the apartment does not exceed 7.5 kW for a single-phase network, where the voltage is 220 V. This includes all electrical appliances and lighting. They select the nearest cable section size in the direction of increasing power. For a copper conductor with a cross section of 4 mm 2 corresponds to 8.3 kW. An aluminum core has an area of ​​​​6 mm 2 per 7.9 kW.

When choosing the cross section of each conductor, one should take into account the possible increase in the load in the future. Therefore, usually take the next largest area in the direction of increase.

In private homes, a three-phase 380 V power supply is used, and most electrical appliances are not designed for this. You can create a voltage of 220 V for them by connecting through a neutral wire with a uniform distribution of the load on all phases. Three-phase technique is also taken into account. It can be machine tools, pumps, heating boilers.

Table of correspondence of the cable section to current and power

Current- conductive cores, mm		Copper conductors of wires and cables
	Voltage 220 V		Voltage 380 V
	Current, A	power, kWt	Current, A	power, kWt
1,5	19	4,1	16	10,5
2,5	27	5,9	25	16,5
4	38	8,3	30	19,8
6	50	11	40	26,4
10	70	15,4	50	33
16	90	19,8	75	49,5
25	115	25,3	90	59,4
35	140	30,8	115	75,9
50	175	38,5	145	95,7
70	215	47,3	180	118,8
95	260	57,2	220	145,2
120	300	66	260	171,6

By current

Sometimes the power of the device is not known for the following reasons: there is no power value in the characteristic, but the rated current is indicated, there is no tag and description.

Since the current with the voltage are known, the power can be calculated as follows:

P = UI∙cos φ,

I - current strength, A;

U is the applied voltage, V.

If the current value is not known, it can be measured by turning on the device in another place. When the power consumption is determined by the formula, the table makes it possible to immediately find out the required cable size. The above table also shows the dependence of the conductor cross section on the magnitude of the current.

By load

Calculation of the cable according to the current load is necessary for protection against overheating. If the current is too high for the cable section, overheating, melting and destruction of the insulation occurs.

The maximum permissible continuous load is the value of the current that can be passed through the cable under laying conditions for a sufficiently long time without overheating. When calculating, all the powers of the devices connected to certain cores are summed up. Then the calculation is made for the load for household networks:

I = P ∑ ∙K and /U - ​​single-phase;

I = P ∑ ∙K and /(√3∙U) - three-phase;

P ∑ - total power of consumers;

By lenght

It is usually required to design extension cords for long distances. In an apartment, this is not required, since the length of the lines is small. But everywhere it is necessary to leave a margin, especially for shields, where protection is connected and neat laying of the wire is needed.

The cable is laid as follows:

1. The locations of the connections are marked: sockets, automatic machines, junction boxes, switches.
2. Distances are measured using a tape measure or a special hand-held length meter. They are more convenient to use, and the result is more accurate. After that, the wire is cut off with a margin.
3. The laying and fastening of the wire is carried out in compliance with the requirements of the PUE.

Cable length meter

Any conductor has electrical resistance, which is influenced by factors:

• choice of material;
• section;
• length.

If the voltage drop exceeds 5%, then take measures to reduce it. If you choose a conductor of a larger cross section, you can reduce the resistance of the section, determined from the formula:

p - resistivity (Ohm mm 2 /m);

R is the total resistance of the wire section (Ohm);

S - cross-sectional area (mm 2);

L is the length of the wire section (m).

When calculating, it should be taken into account that the current flows through one core, and the return occurs through the other. Therefore, the length L is doubled. Despite the fact that the resistance of the wire is small, it creates a significant voltage drop. If R \u003d 0.5 Ohm, then with a current strength of 20 A, the drop will be:

∆U = I R = 20 0.5 = 10 V.

As a percentage, it will be 10/220 100 = 4.5%. The value of losses is close to the maximum allowable.

In a room, it is necessary to take into account the difference between power and lighting loads. For lamps, you can take a copper wire cross section of 1.5 mm 2, and you need to be more careful with sockets. They are most loaded in the kitchen and bathroom, where they constantly turn on the microwave, electric stove, washing machine, dishwasher, and electrical appliances. They try to distribute the load evenly among the socket groups, and the wire is selected with a cross section of 4 mm 2 and even more. Under the amount of current, appropriate sockets and switches are installed.

Wire section. Video

The video below will tell you how to choose the most optimal wire cross-section for each specific situation.

The calculation of the cable in length and in cross section is an important process that does not allow miscalculations. It is necessary to take into account the greatest number of factors, trusting only your own calculations. They must match what the reference table shows. Special requirements must be set for the quality of wiring materials and the characteristics of connected consumers.

Content:

AT electrical networks there are many parameters defined in different ways. Among them there is a special table, the diameter and cross section of the wire with its help are determined with high accuracy. Such precise data is required when adding an electrical load, and the old wire does not have letter markings. However, even the conventions do not always correspond to reality. This is mainly due to the dishonesty of product manufacturers. Therefore, it is best to do your own calculations.

Application of measuring instruments

To determine the diameter of the cores of wires and cables, various methods are widely used. measuring instruments showing the most accurate results. Basically, for these purposes, the use of micrometers and calipers is practiced. Despite the high efficiency, a significant drawback of these devices is their high cost, which is of great importance if the tool is planned to be used only 1-2 times.

As a rule, professional electricians who are constantly engaged in work use special devices. With a competent approach, it becomes possible to measure the diameter of wire cores even on working lines. After obtaining the necessary data, it remains only to use a special formula: The result of the calculation will be the area of ​​the circle, which is the cross section of the core of the wire or cable.

Definition of a section with a ruler

An economical and accurate method is to determine the cross section of cables and wires using an ordinary ruler. In addition to it, you will need a simple pencil and the wire itself. To do this, the core of the wire is stripped of insulation, and then tightly wound onto a pencil. After that, using a ruler, the total length of the winding is measured.

The resulting measurement result must be divided by the number of turns. The result is the diameter of the wire, which will be needed for subsequent calculations. The cable cross section is determined by the previous formula. To obtain more accurate results, there should be as many wound turns as possible, but not less than 15. The turns are tightly pressed together, since the free space contributes to a significant increase in the error in the calculations. You can reduce the error by using a large number of measurements made in different versions.

A significant disadvantage of this method is the possibility of measuring only relatively thin conductors. This is due to the difficulties that arise when winding a thick cable. In addition, it is required to purchase a product sample in advance to perform preliminary measurements.

Table of ratios of diameters and sections

Determining the cross sections of cables and wires using formulas is considered a rather laborious and complex process that does not guarantee an accurate result. For these purposes, there is a special ready-made table, the diameter and cross section of the wire in which they clearly represent their ratio. For example, with a conductor diameter of 0.8 mm, its cross section will be 0.5 mm. A diameter of 1 mm corresponds to a cross section of 0.75 mm, and so on. It is enough just to measure the diameter of the wire, and then look into the table and calculate the desired cross section.

When performing calculations, certain recommendations must be followed. To determine the cross section, it is necessary to use a wire that is completely stripped of insulation. This is due to the possible reduced dimensions of the conductors and a higher insulating layer. In case of any doubt about the cable dimensions, it is recommended to purchase a conductor with a higher cross-section and power reserve. In the case of determining the cross-section of a multi-core cable, the diameters of individual wires are first calculated, the obtained values ​​​​are summarized and used in the formula or in the table.