Section-to-diameter ratio. How to determine the cross-section of a stranded wire by its diameter? Calculation of the current cross-section

When buying or it is always worth paying attention to its actual cross-section, since often in stores you can find cable products with a cross-section that does not correspond to its marking, and significantly. And this, as you know, can lead to overheating of the cable and, as a result, to a short circuit.

Several simple methods will help us to independently calculate the real wire cross-section. The most convenient way is to calculate the cross-section of the wire by its diameter. To do this, you need a micrometer or vernier caliper.

Having measured the diameter of the core, we recall the formula for the area of \u200b\u200ba circle:

For example, let's take a wire on the insulation of which the marking VVGng 3 × 2.5 is indicated. We measure the diameter of the core with a caliper - we get 1.7 mm. Next, we substitute this value into the formula:

Scr \u003d 0.785 x 1.7 x 1.7 \u003d 2.27mm2.

It turns out that the actual cross-section of the wire is 2.27mm2 instead of the declared 2.5.

Everything is clear with a single-core wire, but what about a stranded one?

Everything is about the same here. We take one core from a stranded wire and measure it with a caliper. For example, the diameter turned out to be 0.4 mm.

Scr \u003d 0.785 x 0.4 x 0.4 \u003d 0.125mm2.

Then we count the total number of veins in the wire, suppose 12.

And now we find out the total cross-section of the wire by multiplying the value of one core 0.125 mm2 by the number of cores - 12.

S \u003d 0.125 x 12 \u003d 1.5mm2 - this is the actual cross-section of the wire.

Of course, not everyone has a caliper, and even more so a micrometer, in this case you will have to go the other way.

To do this, from available tools, we need a ruler and a pencil, or some kind of round rod. We remove the insulation from the wire and wind about 10 turns on the rod. The main thing is that the turns fit tightly to each other, without gaps.

We measure the length of the winding with a ruler and divide by the number of turns. We get the diameter of the core. And then, using the same formula, we find the cross-section of the vein. The method is quite accurate, but not very convenient - and in the store, you cannot measure it on and do not wind thick veins.

In order not to calculate the cross-section on the calculator every time, I will lay out below a table of correspondence of diameters and cross-sections of wires, in which there are the most common sizes. You can rewrite it or print it and take it with you to the store. It remains only to measure the diameter of the core and compare with the value from the table. If the measured value differs significantly from the tabulated value, then it is better not to buy such a cable.

The ability to choose the right cable cross-section can be useful to everyone over time, and you do not need to be a qualified electrician for this. Incorrectly calculating the cable, you can expose yourself and your property to serious risk - too thin wires will get very hot, which can lead to a fire.

What is the calculation of the cable cross-section for?

In the main, this slightly complicated procedure is necessary to ensure the safety of both the premises itself and the people in it. Today, mankind has not invented a more convenient method of distributing and delivering electrical energy to the consumer, as by wires. Almost every day people need the services of an electrician - someone needs to connect an outlet, someone needs to install a lamp, etc. It turns out that even such a seemingly insignificant procedure as installing a new lamp is connected with the operation of selecting the required section ... What, then, about connecting an electric stove or water heater?

Failure to comply with standards can lead to a violation of the integrity of the wiring, which often leads to a short circuit or even an electric shock.

If you make a mistake when choosing the cable cross-section and purchase a cable with a smaller conductor area, this will lead to constant heating of the cable, which will cause the destruction of its insulation. Naturally, all this negatively affects the duration of operation of the wiring - there are often cases when, a month after successful installation, the wiring stopped working, and the intervention of a specialist was required.

It should be remembered that the electrical and fire safety in the building, and hence the life of the residents themselves, directly depends on the correctly selected value of the cable section.

Of course, every owner wants to save as much as possible, but you shouldn't do this at the cost of your life, endangering it - after all, as a result of a short circuit, a fire can occur, which may well destroy all property.

To avoid this, before starting the electrical work, you should select the cable with the optimal cross section. For selection, several factors must be taken into account:

• the total number of electrical devices in the room;
• the total power of all devices and the load they consume. To the resulting value should be added "in reserve" 20-30%;
• then, by simple mathematical calculations, convert the resulting value into the cross-section of the wire, taking into account the material of the conductor.

Attention! Due to the lower electrical conductivity, wires with aluminum conductors should be purchased with a larger cross section than copper ones.

What affects the heating of wires

If the wiring heats up during the operation of household appliances, then all necessary measures should be taken immediately to eliminate this problem. There are many factors affecting the heating of wires, but the main ones include the following:

1. Insufficient cable section... In simple terms, we can say this - the thicker the cores of the cable, the more current it can transmit without warming up. The value of this value is indicated in the marking of cable products. You can also measure the cross-section yourself using a vernier caliper (make sure that the wire is not energized) or by the brand of the wire.
2. The material of which the wire is made... Copper conductors transmit voltage to the consumer better, and have less resistance than aluminum conductors. Naturally, they heat up less.
3. Core type... The cable can be single-core (a core consists of one thick rod) or stranded (a core consists of a large number of small wires). A multi-core cable is more flexible, but significantly inferior to a single-core cable in terms of the permissible current strength.
4. Cable laying method... Densely laid wires, which are at the same time in the pipe, heat up significantly more than open wiring.
5. Insulation material and quality... Inexpensive wires, as a rule, have poor quality insulation, which negatively affects their resistance to high temperatures.

How is the power consumption calculation done?

You can calculate the approximate cross-section of the cable yourself - it is not necessary to resort to the help of a qualified specialist. The data obtained as a result of the calculations can be used to buy a wire, however, the electrical work itself should be trusted only by an experienced person.

The sequence of actions when calculating the cross section is as follows:

1. A detailed list of all electrical appliances in the room is compiled.
2. The passport data of the power consumption of all found devices is established, after which the continuity of operation of one or another equipment is determined.
3. Having identified the value of the power consumption from devices that operate constantly, this value should be summed up by adding a coefficient equal to the value of periodically turning on electrical appliances (that is, if the device will work only 30% of the time, then add a third of its power)
4. Next, we look for the obtained values \u200b\u200bin a special table for calculating the wire cross-section. For greater assurance, it is recommended to add 10-15% to the obtained power consumption value.

To determine the necessary calculations for the selection of the cross-section of electrical wiring cables according to their power within the network, it is important to use data on the amount of electrical energy consumed by devices and current devices.

At this stage, it is necessary to take into account a very important point - the data of power-consuming devices give not an accurate, but an approximate, averaged value. Therefore, it is necessary to add about 5% of the parameters specified by the equipment manufacturer to this mark.

Most of the far from the most competent and qualified electricians are sure of one simple truth - in order to correctly route electrical wires for lighting sources (for example, for lamps), you need to take wires with a cross section of 0.5 mm², for chandeliers - 1, 5 mm² and for sockets 2.5 mm².

Only incompetent electricians think about it and think so. But what if, for example, a microwave oven, a kettle, a refrigerator and lighting are operating in the same room at the same time, for which wires with different cross sections are needed? This can lead to a variety of situations: short circuit, rapid damage to the wiring and the insulation layer, as well as fire (this is a rare case, but still possible).

Exactly the same not the most pleasant situation can occur if a person connects a multicooker, a coffee maker and, say, a washing machine to the same outlet.

Features of calculating the power of hidden wiring

If the design documentation implies the use of hidden wiring, then it is necessary to purchase cable products "with a margin" - about 20-30% should be added to the obtained cable cross-section value. This is done to avoid heating the cable during operation. The fact is that in a confined space and lack of air access, the heating of the cable occurs much more intensively than when installing open wiring. If, in closed channels, it is planned to lay not one cable, but several at once, then the cross-section of each wire should be increased by at least 40%. It is also not recommended to lay various wires tightly - ideally, each cable should be in a corrugated pipe, which provides its additional protection.

Important! It is by the value of the power consumption that professional electricians are guided when choosing a cable section, and only this method is correct.

How to calculate cable cross-sections by power

With a sufficient cable cross-section, the electric current will flow to the consumer without causing heating. Why is heating happening? We will try to explain as clearly as possible. For example, a kettle with a power consumption of 2 kilowatts is plugged into the outlet, but the wire going to the outlet can transmit only 1 kilowatt of current to it. The capacity of a cable is related to the resistance of the conductor - the greater it is, the less current can be transmitted through the wire. As a result of the high resistance in the wiring, the cable heats up, gradually destroying the insulation.

With the appropriate cross-section, the electric current reaches the consumer in full, and the wire does not heat up. Therefore, when designing wiring, you should take into account the power consumption of each electrical device. This value can be found from the technical data sheet for the electrical appliance or from the label affixed to it. Summing up the maximum values \u200b\u200band using a simple formula:

and we get the value of the total current.

Pn denotes the power of the electrical appliance indicated in the passport, 220 is the nominal voltage.

For a three-phase system (380 V), the formula looks like this:

I \u003d (P1 + P2 + .... + Pn) / √3 / 380.

The resulting I value is measured in Amperes, and on the basis of it, the appropriate cable section is selected.

It is known that the carrying capacity of a copper cable is 10 A / mm, for an aluminum cable the value of the carrying capacity is 8 A / mm.

For example, we calculate the size of the cable cross-section for connecting a washing machine, the power consumption of which is 2400 watts.

I \u003d 2400 W / 220 V \u003d 10.91 A, rounding up we get 11 A.

11 A + 5 A \u003d 16 A.

If we take into account that three-core cables are used in apartments and look at the table, then the value of 19 A is close to 16 A, therefore, to install the washing machine, a wire with a cross section of at least 2 mm² is required.

Cable cross-section table with respect to current strength

Current section wire power core (mm 2)		Current (A), for wires laid
	Open- then		in one pipe
		two one- vein	three one- vein	four one- vein	one two vein	one three vein
0,5	11	-	-	-	-	-
0,75	15	-	-	-	-	-
1	17	16	15	14	15	14
1,2	20	18	16	15	16	14,5
1,5	23	19	17	16	18	15
2	26	24	22	20	23	19
2,5	30	27	25	25	25	21
3	34	32	28	26	28	24
4	41	38	35	30	32	27
5	46	42	39	34	37	31
6	50	46	42	40	40	34
8	62	54	51	46	48	43
10	80	70	60	50	55	50
16	100	85	80	75	80	70
25	140	115	100	90	100	85
35	170	135	125	115	125	100
50	215	185	170	150	160	135
70	270	225	210	185	195	175
95	330	275	255	225	245	215
120	385	315	290	260	295	250
150	440	360	330	-	-	-
185	510	-	-	-	-	-
240	605	-	-	-	-	-
300	695	-	-	-	-	-
400	830	-	-	-	-	-

How to choose conductor cross-sections

There are several more criteria that must be met by the cross-section of the wires used:

1. Length of cable... The longer the wire is in length, the greater the current losses are observed in it. This again occurs as a result of an increase in resistance, which increases as the length of the conductor increases. This is especially true when using aluminum wiring. When using copper wires for organizing electrical wiring in an apartment, the length is usually not taken into account - the standard margin of 20-30% (with hidden wiring) is more than enough to compensate for possible increases in resistance associated with the length of the wire.
2. Type of wires used... In household power supply 2 types of conductors are used - based on copper or aluminum. Copper wires are of better quality and have less resistance, but aluminum is cheaper. With full compliance with the standards, aluminum wiring copes with its tasks no worse than copper, so you need to carefully weigh your choice before buying a wire.
3. Switchboard configuration... If all the wires supplying consumers are connected to one machine, then it is he who will be the weak point in the system. A heavy load will lead to heating of the terminal blocks, and non-compliance with the rating will lead to its constant operation. It is recommended to divide the wiring into several "beams" with the installation of a separate machine.

In order to determine the exact data for choosing the cross-section of electrical wiring cables, it is necessary to take into account any, even the most insignificant parameters, such as:

1. Type and type of insulation of electrical wiring;
2. Length of sections;
3. Ways and options for laying;
4. Features of the temperature regime;
5. Humidity level and percentage;
6. The maximum possible amount of overheating;
7. The difference in the powers of all current receivers belonging to the same group. All of these metrics and more can dramatically increase efficiency and energy use at any scale. In addition, correct calculations will help to avoid overheating or rapid abrasion of the insulating layer.

In order to correctly determine the optimal cable section for any human domestic needs, it is necessary in all general cases to use the following standardized rules:

• for all sockets that will be installed in the apartment, it is necessary to use wires with the appropriate cross-section of 3.5 mm²;
• for all elements of spot lighting, it is necessary to use electrical wiring cables with a cross section of 1.5 mm²;
• as for devices of increased power, then cables with a cross section of 4-6 mm² should be used for them.

If in the process of installation or calculations some doubts arise, it is better not to act blindly. Ideally, refer to the appropriate table of calculations and standards.

Copper cable section table

Section of conductors carrying current (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	46	10,1	40	26,4
10	70	15,4	50	33
16	80	18,7	75	49,5
25	115	25,3	90	59,4
35	135	29,7	115	75,9
50	175	38,5	145	95,7
70	215	47,3	180	118,8
95	265	57,2	220	145,2
120	300	66	260	171,6

Aluminum cable section table

The cross-section of the current-carrying part of any manufactured type of cable product is one of its most important characteristics. At the same time, if the insulating properties of the cable relate more to the place of installation, the type of installation and the operating voltage, then the cross-section is the value on which the load on this network directly depends, that is, the power of the connected equipment. This parameter should be taken into account when organizing and designing absolutely any type of wiring, whether it be industrial facilities or private residential premises. For all types of electrical equipment, standard wire and cable sections are provided. It is measured in mm 2 and is calculated according to the diameter of the current-carrying conductor, as well as the area of \u200b\u200bthe circle.

Standard range of sections

There is a standard range of conductor cross-sections produced by cable manufacturers: 0.5; 0.75; one; 1.5; 2.5; 4; 6; ten; 16; 25; 35; fifty; 70; 95; 120; 150; 185; 240; 300; 400; 500; 625; 800; 1000; 1200; 1600 sq. mm. In this case, the maximum cross-section of the conductive core can reach 6000 mm.kv. (cable KSVDSP-6000).

It is important to note that the minimum value for an aluminum cable is 2.5 mm 2. This is due to the low strength of this metal, since the number of bends before the moment of refraction is much less than that of copper, that is, it can easily break at the points of attachment during installation.

Good to know

For private houses and apartments, where a line voltage of 0.4 kV is used and, accordingly, phase 220 V, a wire with a cross section from the very minimum value is most often used: 2.5 - aluminum and 1.5 mm2. copper. In general, these standard conductors are suitable for lighting circuits.

All other sections and, accordingly, their diameters depend on the power and, naturally, the current in the circuits of household electrical equipment. To determine the cross-section required for wiring, the table below is given. According to it, knowing the total power of electrical devices connected to this network, you can easily find the required size of the conductors.

In this case, it is still recommended to choose a cross-section with a margin, that is, the nearest larger standard value. For example, the voltage in the network is single-phase 220 Volts and the owner of the premises needs to power the devices with a power of, say, 7 kW. According to the table, there is no such power, but there are 5.9 and 8.3 kW. For copper wiring, you need a cable with a conductor cross section of 4 mm 2. If the budget is limited and the task is to carry out wiring from aluminum, then the nearest larger parameter indicated in the table will be 7.9 kW, which corresponds to a 6 mm 2 core.

You can also combine wires of different cross-sections, for example, from an input machine to a junction box, more, and then when wiring occurs to groups of electrical consumers or to luminaires, you can lay a smaller wire. The main thing is to remember the rules, in case of such a need arises.

In production, the power of electrical equipment is much higher than in everyday life, and the voltage in high-voltage networks is 6 kV, 10 kV, 35 kV, etc. That is why the standard cross-sections of wires and cables are more diverse here. This value is calculated with a large margin, since the main most powerful receivers of electricity are electric motors, and during start-up they can amplify the current in the power circuits supplying them by 5-7 times higher than the nominal.

However, to power lighting equipment and secondary switching circuits, carried out by control cables, all the same wires of 1.5–2.5 mm 2 are widely used and they are quite enough.

For power circuits 6 kV, aluminum cable products from 120 mm 2 are often used. If such a cable cross-section is not enough, then two lines are started up, connected in parallel to each other, thereby dividing the load on each of them. In everyday life, such techniques are inappropriate. For especially powerful equipment, there is a wiring of circuits with four or even six conductors connected in parallel.

There are times when cables with a rather large cross-section of conductors are also needed for low-voltage circuits, as, for example, in the case of organizing welding.

The choice of the wire cross-section is very important and individual, therefore, in production, this is done by entire design bureaus or individual companies, which include experienced design engineers.

How to determine the wire size? Both beginner masters and simple guys come to this question sooner or later. Determination of the wire cross-section helps to replace the wiring: the load was calculated and it became clear that these conditions and current require certain parameters of the wire cross-section.

Let's say 2.5 mm2. You buy a cable or wire, install electrical wiring. After a while, the line is suddenly damaged. The channel is opened and it turns out that the insulation of the wires has melted. If the cross-section does not correspond to the load, such a situation is simply inevitable.

The reason for what happened may be:

1. incorrect calculation and selection of wire cross-section;
2. lack of technical information on the packaging of the wire or its unreliability.

An incorrect definition of the section can lead to negative consequences. It is super important to be able to correctly calculate the section parameters. This way you can avoid unpleasant situations and save a decent amount.

Today the editors tell you how to find out the wire size. Bonus - we made several calculation options so that everyone could choose the best one for themselves.

How to determine the wire size: 3 main ways

Calipers

Pencil + ruler

Table

Option number 1: find out the cross-section of the wire using a vernier caliper

Figure 1 - The wire has a brand and a section. It happens that the cable is defective, that is, truncated. For example, you need VVG 3x2.5, but in fact 3x2.1, although it says 3x2.5

A vernier caliper is used to determine the cross-section or triangular section of the conductor of the wire and cable. Below is an example of calculations using the device.

To get started, remember the formula for determining the area of \u200b\u200ba circle:

where n \u003d 3.14; r is the radius of the circle.

We will use a simplified version of the formula, adapted to our case:

d is the diameter of the circle (core).

For clarity, we divide the number n by 4. The result is the formula:

We determine the diameter of the wire: this is how we find out the cross-sectional area. To do this, you need to clean the wire core. Then measure its diameter with a vernier caliper.

It turned out 1.78 mm. This number must be put into the expression. Eventually:

Let's round to hundredths and get the wire cross-section value of 2.79 mm2.

Option number 2: determine the cross-section of the wire using a pencil and a ruler

Not everyone has special equipment at home. And buying it for a single use is stupid. We will tell you how to determine the cross section without professional devices.

We take the wire and strip it lengthwise. Enough 30-50 cm. After winding the wire on a pen or pencil. You need to reel tightly to each other. Then we count the number of turns obtained, measure the length. Let's say there are 19 turns with a total length of 32 mm.

To find out the diameter, you need to divide the length by the number of turns. In our case, 32: 19 \u003d 1.684. According to the principle given in the first option, we substitute the diameter in the formula. We got 2.23 mm squared.

How accurate is this method? The magnitude of the error will depend on the number of turns: the more there are, the smaller the error.

IMPORTANT! This measurement option is not suitable for an industrial scale, however, for a home mode it is what you need.

Option number 3: determine the cross-section of the wire using the table

You can also use the correspondence tables of the PUE. They simplify work, as they indicate the long-term allowable currents for copper and aluminum wires. This takes into account the types of insulation and shell.

Below is a simplified table for the most comfortable use. With its help, you can determine the cross-section of three-core, four-core, as well as five-core wires under conditions of single-phase and three-phase loads (220 V / 380 V). To do this, it is enough to know the load current and its power.

• In the air (trays, boxes, voids, channels)

Copper conductors

Current, A	220 V	380 V
19	4,1	12,5
25	5,5	16,4
35	7,7	23
42	9,2	27,6
55	12,1	36,2
75	16,5	49,3
95	20,9	62,5
120	26,4	78,9
145	31,9	95,4
180	39,6	118,4
220	48,4	144,8
260	57,2	171,1
305	67,1	200,7
350	77	230,3

Aluminum conductors

Current, A	220 V	380 V
-	-	-
19	4,1	12,5
27	5,9	17,7
32	7	21
42	9,2	27,6
60	13,2	39,5
75	16,5	49,3
90	19,8	59,2
110	24,2	72,4
140	30,8	92,1
170	37,4	111,9
200	44	131,6
235	51,7	154,6
270	59,4	177,7

• In the ground

Copper conductors

Current, A	220 V	380 V
27	5,9	17,7
38	8,3	25
49	10,7	32,5
60	13,2	39,5
90	19,8	59,2
115	25,3	75,7
150	33	98,7
180	39,6	118,5
225	49,5	148
275	60,5	181
330	72,6	217,2
385	84,7	253,4
435	95,7	286,3
500	110	329

Current, A	220 V

Cross-section of the lead-in wire: how to find out?

IMPORTANT! The rating of the input circuit breaker must be agreed with the power supply institution. Without this procedure, it is prohibited to change it, because this can affect the selectivity of the operation of the protection devices located in the power supply circuit in the ASU / TP (including the allocated power for a certain housing).

You can find out the parameters of the denomination in two ways:

• in an organization specializing in energy saving;
• in the documentation, which specifies the technical conditions for connection to the networks.

For clarity, let's take the conditional values \u200b\u200bof the technical specifications. For example, the power is 5 kW, the rating of the input machine is 25 A and single-phase power (220 V).

It's simple. It is necessary to take into account the type of wiring, the material used for the production of conductors and the voltage. We select the cross-section so that the long-term permissible current of the cable is higher than the rating of the input machine.

For example, we decided to make the lead-in cable into the house with a copper three-core VVGng brand, laying it in an open way. Therefore, a suitable section will be at least 4 mm2, which means that you need to buy VVGng (3x4).

Remember about the "conventional breaking current" of the machine: an automatic machine providing a rated current of 25 A has a "conventional breaking current" 1.45 · 25 \u003d 36.25 A.

In such conditions, the cold machine will shut down after about an hour.

A cable with a cross-section of 4 mm2 has a long-term permissible current of 35 A, the indicator of the "conventional breaking current" is 36.25 A. The values \u200b\u200bdo not differ much, nothing can be changed. However, it is better to choose a 6 mm2 lead-in cable with a continuous allowable current of 42 A.

How to determine what is the cross section of the wire of the outlet lines?

Every electrical appliance has power. The parameters can be found in the passport of the product or on the sticker attached by the manufacturer. It is measured in watts. Let's take conditional parameters as an example.

Let's say you need a power line for a washing machine. The power of the device is 2.4 kW. We use a copper three-core cable of the VVGng brand, lay it so that it is not visible. From this we conclude that the cross section should be at least 1.5 mm2. This means that you need a VVGng cable (3x1.5).

If you use the outlet only to connect the washing machine, these parameters will be sufficient. To protect the cable, you will need an automatic machine with a rated current of 10 A.

However, sockets are rarely installed for such reasons. For example, you will need to connect another device to the same network, and each electrical device has its own power. It is more advisable to use a copper cable with a cross-section of 2.5 mm2 for socket lines. For protection, you need to install an automatic machine with a rating of 16 A.

How to find out the wire cross-section of a three-phase motor?

Suppose there is a three-phase asynchronous motor of the AIR71A4U2 type. Its power is 550 W, and the windings are connected in a star for a voltage of 380 V. To find out which section will be optimal, you need to look at the rated motor current, which is indicated on the sticker of the device. Let's say it is 1.6 A.

IMPORTANT! Sometimes it happens that there is no sticker. Then you can look up the data in the lookup tables. We're going to use a copper cable, and we'll run it through the air. To determine the section, refer to the table. We get 1.5 mm2. It can also be recognized by the power of the consumer.

Depending on the situation, you can choose the most convenient way. Experienced electricians are said to be able to determine the cross section visually by eye. But for now, we advise beginners to refrain and still use our recommendations. Good luck!

The most important thing when installing electrical wiring is to choose a high-quality cable, because you can always easily replace an outlet or a switch, and it will be difficult to replace a burned-out cable, not to mention what the consequences of this may be. Very often the cross-section of the cable differs from that declared by the manufacturer, because the reduction in the cross-section allows unscrupulous manufacturers to save on the most expensive component - copper. In order not to become a victim of deception, it is advisable to measure its cross-section yourself before buying a cable, and we will tell you how to determine the cable cross-section by diameter in three simple ways in this article.

Method number 1 - using a caliper or micrometer

Using a caliper or micrometer, the diameter of the conductive core of the cable stripped from the insulation is measured. It is advisable to measure it on several sections of the conductor, as well as on all conductors of the cable, and record the smallest indicators. If you take measurements with a micrometer, then the measurement must be made on a flat section of the vein, so the indicators will be more accurate.

As you know from the school mathematics course, the area of \u200b\u200ba circle (and in our case it will be the cross-sectional area of \u200b\u200bthe cable) is calculated by the formula S \u003d πR² and if this formula is simplified by dividing the number π by 4, then as a result we get a formula by which you can determine the cable cross-section by diameter:

Method number 2 - using a ruler

What to do if you don't have a caliper at hand, or even more than a micrometer, how to determine the cable cross-section by diameter without these tools? The old and proven method of measuring with a ruler and a pencil will come to the rescue.

The measurement principle with this method is as follows: the cleaned core is wound around a pencil, as shown in the figure below. The minimum number of turns should be 15-20, but here you also need to proceed from the thickness of the conductor, if it is too thin, then it is advisable to wind more turns.

To reduce the measurement error, the turns must be wound as tightly as possible. Next, using a ruler, we measure the length of the wound wire and divide it by the number of turns, we get the diameter of the core, everything is simple.

Using the formula already known to us, we determine the cable cross-section by diameter. For clarity, let's give an example: let's say we wound 20 turns of wire, and got the result 19.6 mm, divide this number by the number of turns 20, and we get a diameter of 0.98 mm. Using the formula, we calculate: 0.785 * 0.98 * 0.98 \u003d 0.753914 mm², round up, and we get 0.75 squares.

The disadvantage of this method for determining the cable cross-section by diameter is that it will be difficult to wind a wire with a large cross-section with it, but for small cross-sections this method, on the contrary, will give a more accurate result. In addition, you will probably need to buy a piece of wire for testing, because no seller will allow such experiments to be carried out at home.

Method number 3 - using the table

The easiest way to determine the cross-section of the cable is by diameter, but you still need a measuring tool, a vernier caliper, or a micrometer. We measure the thickness of the core diameter, and use the table to determine the cross section.

Conductor diameter, mm	Cable cross-section, mm.kv.
0,80	0,5
0,98	0,75
1,13	1,0
1,38	1,5
1,60	2,0
1,78	2,5
2,26	4,0
2,76	6,0
3,57	10,0
4,51	16,0
5,64	25,0
6,68	35,0
7,98	50,0
9,44	70,0
11,00	95,0
12,36	120,0
13,82	150,0
15,35	185,0
17,48	240,0
19,54	300,0
22,57	400,0

In conclusion, it must be said that it is also important to pay attention to the composition of the conductive core, most often wires and cables with a copper core are forged. Buy cable products from a trusted retailer. Our store sells only high-quality, certified products from proven domestic manufacturers. If you want to ask a question related to the choice of cable products, then you can always consult with our consultants, you just need to contact us through