What load is the 4x10 copper cable designed for? How to choose the right cable cross-section. Wire cross-sectional area

In order to correctly lay the electrical wiring, ensure uninterrupted operation of the entire electrical system and eliminate the risk of fire, before purchasing a cable, it is necessary to calculate the loads on the cable to determine the required cross-section.

There are several types of loads, and for the highest quality installation of the electrical system, it is necessary to calculate the loads on the cable according to all indicators. The cable cross-section is determined by load, power, current and voltage.

Power section calculation

In order to produce, it is necessary to add up all the indicators of electrical equipment operating in the apartment. Calculation of electrical loads on the cable is carried out only after this operation.

Calculation of cable cross-section by voltage

Calculation of electrical loads on a wire necessarily includes. There are several types of electrical network - single-phase at 220 volts, and three-phase at 380 volts. In apartments and residential premises, as a rule, a single-phase network is used, so during the calculation process it is necessary to take this point into account - the voltage must be indicated in the tables for calculating the cross-section.

Calculation of cable cross-section by load

Table 1. Installed power (kW) for cables laid openly

Core cross-section, mm 2	Cables with copper conductors		Cables with aluminum conductors
	220 V	380 V	220 V	380 V
0,5	2,4
0,75	3,3
1	3,7	6,4
1,5	5	8,7
2	5,7	9,8	4,6	7,9
2,5	6,6	11	5,2	9,1
4	9	15	7	12
5	11	19	8,5	14
10	17	30	13	22
16	22	38	16	28
25	30	53	23	39
35	37	64	28	49

Table 2. Installed power (kW) for cables laid in a groove or pipe

Core cross-section, mm 2	Cables with copper conductors		Cables with aluminum conductors
	220 V	380 V	220 V	380 V
0,5
0,75
1	3	5,3
1,5	3,3	5,7
2	4,1	7,2	3	5,3
2,5	4,6	7,9	3,5	6
4	5,9	10	4,6	7,9
5	7,4	12	5,7	9,8
10	11	19	8,3	14
16	17	30	12	20
25	22	38	14	24
35	29	51	16

Each electrical appliance installed in the house has a certain power - this indicator is indicated on the nameplates of the devices or in the technical data sheet of the equipment. To implement, it is necessary to calculate the total power. When calculating the cable cross-section for the load, it is necessary to rewrite all electrical equipment, and you also need to think about what equipment may be added in the future. Since the installation is carried out for a long time, it is necessary to take care of this issue so that a sharp increase in load does not lead to an emergency.

For example, you have a total voltage of 15,000 W. Since the vast majority of residential premises have a voltage of 220 V, we will calculate the power supply system taking into account a single-phase load.

Next, you need to consider how much equipment can operate simultaneously. As a result, you will get a significant figure: 15,000 (W) x 0.7 (70% simultaneity factor) = 10,500 W (or 10.5 kW) - the cable must be designed for this load.

You also need to determine what material the cable cores will be made of, since different metals have different conductive properties. In residential premises, copper cable is mainly used, since its conductive properties are much higher than those of aluminum.

It is worth considering that the cable must have three cores, since grounding is required for the electrical supply system in the premises. In addition, it is necessary to determine what type of installation you will use - open or hidden (under plaster or in pipes), since the calculation of the cable cross-section also depends on this. Once you have decided on the load, core material and type of installation, you can look at the required cable cross-section in the table.

Calculation of cable cross-section for current

First you need to calculate the electrical loads on the cable and find out the power. Let's say that the power turned out to be 4.75 kW, we decided to use a copper cable (wire) and lay it in a cable channel. is produced according to the formula I = W/U, where W is power, and U is voltage, which is 220 V. In accordance with this formula, 4750/220 = 21.6 A. Next, look at table 3, we get 2, 5 mm.

Table 3. Permissible current loads for cables with copper conductors laid hidden

Core cross-section, mm	Copper conductors, wires and cables
	Voltage 220 V	Voltage 380 V
1,5	19	16
2,5	27	25
4	38	30
6	46	40
10	70	50
16	85	75
25	115	90
35	135	115
50	175	145
70	215	180
95	260	220
120	300	260

Of the cross-sections of current-carrying conductors of a copper wire indicated in the question, a wire with a cross-section of 1 square millimeter is perhaps the most rarely used. This wire can be used to make internal switching of a chandelier or lamp; for each light bulb in the chandelier it will be more than enough, because individually they rarely exceed 500 Watts. With a wire of 1 square millimeter, today you can also install a lighting line for internal electrical wiring in which energy-saving or LED lamps will be used; their power is low and a wire of one square is enough. Why in a private house? Yes, because the wiring of apartments is still done according to the PUE and must have a cross-section of at least 1.5 square meters. The total power that the wire cross-section will withstand 1 square millimeter - 2200 Watts (2.2 Kilowatts) (10 Amps) You can connect any device whose power does not exceed this value. For example, it is not critical to connect a hair dryer, computer, TV, video set-top box, power supply for video surveillance systems, mixer... When determining the power characteristics of a device, you must first of all refer to its passport data indicated in the passport plate (usually stuck on the device in an inconspicuous place)

Wire with a cross-section of 1.5 is usually used in lighting, although the power reserve in the lighting line is not very bad. By the way, the maximum permissible load on the wire should not be taken as standard; there should always be a reserve of power, about 10 percent. In this case, your wire will never heat up even if all consumers are turned on for a long time, especially the connection points, which are the weakest link in any electrical circuit.

Below is a table of the ratios of the cross-sectional area of ​​the core, permissible current and power. So these are the peak values, subtract 10 percent from them and your wiring will not overheat with any installation method - closed or open wiring.

As you noticed, the value of current and power for different voltages is also different. The question does not indicate the voltage, so I give it for both a 220 Volt network and a 380 Volt network.

So what can we connect in a 220 Volt household network to the wire in -

- 1.5 square- 3500 Watt. This can be at the same time an electric kettle of 2 Kilowatts + a Hairdryer of 250 Watts + a mixer of 250 Watts + an iron of 1 Kilowatt.

- 2.5 square- 5500 Watt. This can be at the same time, all the same, a 2 Kilowatt electric kettle + a 250 Watt hair dryer + a 250 Watt mixer + a 1 Kilowatt iron + a 500 Watt TV + a 1400 Watt vacuum cleaner.

This is just a calculation of power with a margin based on the capabilities of the wire.

You may ask why I didn’t give the number of consumers and their power for a wire with a cross-section of 2 squares? Yes, because the main cross-section of copper wires is 0.75; 1; 1.5; 2.5; 4; 6; 10 squares. I do not exclude that for a narrow purpose a copper wire with a cross-section of 2 square meters. mm. and there is, but not in retail sale.

The question emphasizes “..in my own words..” but nevertheless, for educational purposes, I will give a table of the ratios of the power of electrical appliances to the current consumed, so it will be easier to correlate the existing device, its power (or the total power of several devices) and the current consumed by them and the corresponding cross-section of the copper core.

Seeing this sign and knowing that 1 square millimeter of wire can withstand a current of 10 Amps, we can easily calculate the maximum possible power for our wire.

For example, an electric kettle with a power of 1500 Watt consumes a current of 6.8 Amperes. It turns out that for a wire with a cross-section of 1 square, powering such a kettle will not be critical, even with a good power reserve. But for a kettle with a power of 2000 Watts, a wire of the same cross-section will already lie in the “red zone” of the permissible load, and its constant use for this purpose is unacceptable; you need to take a larger cross-section.

The choice of cross-sectional area of ​​wires (in other words, thickness) is given much attention in practice and in theory.

In this article we will try to understand the concept of “sectional area” and analyze reference data.

Calculation of wire cross-section

Strictly speaking, the concept of “thickness” for a wire is used colloquially, and the more scientific terms are diameter and cross-sectional area. In practice, the thickness of the wire is always characterized by its cross-sectional area.

S = π (D/2) 2, Where

• S– wire cross-sectional area, mm 2
• π – 3,14
• D– diameter of the conductor of the wire, mm. It can be measured, for example, with a caliper.

The formula for the cross-sectional area of ​​a wire can be written in a more convenient form: S = 0.8 D².

Amendment. Frankly, 0.8 is a rounded factor. More precise formula: π (1/2) 2 = π/4 = 0.785. Thanks to attentive readers;)

Let's consider copper wire only, since in 90% of electrical wiring and installation it is used. The advantages of copper wires over aluminum wires are ease of installation, durability, and reduced thickness (at the same current).

Subscribe! It will be interesting.

But with an increase in diameter (sectional area), the high price of copper wire eats up all its advantages, so aluminum is mainly used where the current exceeds 50 Amperes. In this case, a cable with an aluminum core of 10 mm 2 or thicker is used.

The cross-sectional area of ​​the wires is measured in square millimeters. The most common cross-sectional areas in practice (in household electrics): 0.75, 1.5, 2.5, 4 mm2

There is another unit for measuring the cross-sectional area (thickness) of a wire, used mainly in the USA - AWG system. On Samelektrika there is also a conversion from AWG to mm 2.

Regarding the selection of wires, I usually use catalogs from online stores, here is an example of copper. They have the largest selection I've ever seen. It’s also good that everything is described in detail - composition, applications, etc.

I also recommend reading my article, there are a lot of theoretical calculations and discussions about voltage drop, wire resistance for different cross-sections, and which cross-section to choose is optimal for different permissible voltage drops.

In the table solid wire– means that there are no more wires passing nearby (at a distance of less than 5 wire diameters). Twin wire– two wires side by side, usually in the same common insulation. This is a more severe thermal regime, so the maximum current is less. And the more wires in a cable or bundle, the less the maximum current for each conductor must be due to possible mutual heating.

I find this table not very convenient for practice. After all, most often the initial parameter is the power of the electricity consumer, and not the current, and based on this you need to choose a wire.

How to find the current knowing the power? You need to divide the power P (W) by the voltage (V), and we get the current (A):

How to find power knowing current? You need to multiply current (A) by voltage (V), we get power (W):

These formulas are for the case of active load (consumers in residential premises, such as light bulbs and irons). For reactive loads, a factor of 0.7 to 0.9 is usually used (in industry where large transformers and electric motors operate).

I offer you a second table in which initial parameters - current consumption and power, and the required values ​​are the wire cross-section and the shutdown current of the protective circuit breaker.

Selecting the thickness of the wire and circuit breaker based on power consumption and current

Below is a table for selecting the wire cross-section based on known power or current. And in the right column is the choice of the circuit breaker that is installed in this wire.

table 2

Max. power, kW	Max. load current, A	Section wires, mm 2	Machine current, A
1	4.5	1	4-6
2	9.1	1.5	10
3	13.6	2.5	16
4	18.2	2.5	20
5	22.7	4	25
6	27.3	4	32
7	31.8	4	32
8	36.4	6	40
9	40.9	6	50
10	45.5	10	50
11	50.0	10	50
12	54.5	16	63
13	59.1	16	63
14	63.6	16	80
15	68.2	25	80
16	72.7	25	80
17	77.3	25	80

Critical cases are highlighted in red, in which it is better to play it safe and not skimp on the wire by choosing a wire thicker than indicated in the table. And the current of the machine is less.

Looking at the plate, you can easily choose current wire cross-section, or wire cross-section by power.

And also - select a circuit breaker for a given load.

This table shows the data for the following case.

• Single phase, voltage 220 V
• Ambient temperature +30 0 C
• Laying in the air or in a box (in a closed space)
• Three-core wire, in general insulation (cable)
• The most common TN-S system is used with a separate ground wire
• The consumer reaching maximum power is an extreme but possible case. In this case, the maximum current can operate for a long time without negative consequences.

If the ambient temperature is 20 0 C higher, or there are several cables in the bundle, then it is recommended to select a larger cross-section (the next one in the series). This is especially true in cases where the operating current value is close to the maximum.

In general, in case of any controversial and doubtful issues, for example

• possible future increase in load
• high inrush currents
• large temperature changes (electrical wire in the sun)
• fire hazardous premises

you need to either increase the thickness of the wires, or approach the choice in more detail - refer to formulas and reference books. But, as a rule, tabular reference data is quite suitable for practice.

The thickness of the wire can be determined not only from reference data. There is an empirical (experienced) rule:

Rule for choosing wire cross-sectional area for maximum current

You can select the required cross-sectional area of ​​the copper wire based on the maximum current using this simple rule:

The required wire cross-sectional area is equal to the maximum current divided by 10.

This rule is given without reserve, back to back, so the result must be rounded up to the nearest standard size. For example, the current is 32 Amps. You need a wire with a cross section of 32/10 = 3.2 mm 2. We choose the closest one (naturally, in the larger direction) - 4 mm 2. As you can see, this rule fits well into the tabular data.

Important note. This rule works well for currents up to 40 Amps.. If the currents are greater (this is already outside the boundaries of an ordinary apartment or house, such currents are at the input) - you need to choose a wire with an even larger margin - divide not by 10, but by 8 (up to 80 A)

The same rule can be stated for finding the maximum current through a copper wire with a known area:

The maximum current is equal to the cross-sectional area multiplied by 10.

And in conclusion - again about the good old aluminum wire.

Aluminum conducts current less well than copper. This is enough to know, but here are some numbers. For aluminum (the same cross-section as the copper wire) at currents up to 32 A, the maximum current will be only 20% less than for copper. At currents up to 80 A, aluminum conducts current 30% worse.

For aluminum the rule of thumb would be:

The maximum current of an aluminum wire is equal to the cross-sectional area multiplied by 6.

I believe that the knowledge given in this article is quite enough to choose a wire based on the ratios “price/thickness”, “thickness/operating temperature” and “thickness/maximum current and power”.

That's basically all I wanted to tell you about wire cross-sectional area. If something is not clear or you have something to add, ask and write in the comments. If you are interested in what I will publish next on the SamElectric blog, subscribe to receive new articles.

Table for selecting a circuit breaker for different wire cross-sections

As you can see, the Germans are playing it safe and are providing for a larger reserve compared to us.

Although, perhaps this is because the table was taken from instructions from “strategic” industrial equipment.

Regarding the selection of wires, I usually use catalogs from online stores, here is an example of copper. They have the largest selection I've ever seen. It’s also good that everything is described in detail - composition, applications, etc.

A good Soviet book on the topic of the article:

/ Brochure from the Electrician's Library. Provides instructions and calculations necessary for selecting cross-sections of wires and cables up to 1000 V. Useful for those who are interested in primary sources., zip, 1.57 MB, downloaded: 385 times./

Calculating the cable (wire) cross-section is an equally important step when designing the electrical circuit of an apartment or house. The safety and stability of electricity consumers depends on the correct choice and quality of electrical installation work. At the initial stage, it is necessary to take into account such initial data as the planned power consumption, the length of the conductors and their type, the type of current, and the method of wiring installation. For clarity, we will consider the method for determining the cross section, the main tables and formulas. Also, you can use the special calculation program presented at the end of the main material.

Power section calculation

The optimal cross-sectional area allows current to pass without possible overheating of the wires. Therefore, when designing electrical wiring, first of all, find the optimal wire cross-section depending on the power consumption. To calculate this value, you must calculate the total power of all devices that you plan to connect. At the same time, take into account the fact that not all consumers will connect at the same time. Analyze this frequency to select the optimal diameter of the conductor core (more details in the next paragraph “Calculation based on load”).

Table: Approximate power consumption of household electrical appliances.

Name	Power, W
Lighting	1800-3700
TVs	120-140
Radio and audio equipment	70-100
Refrigerators	165-300
Freezers	140
Washing machines	2000-2500
Jacuzzi	2000-2500
Vacuum cleaners	650-1400
Electric irons	900-1700
Electric kettles	1850-2000
Hot water dishwasher	2200-2500
Electric coffee makers	650-1000
Electric meat grinders	1100
Juicers	200-300
Toasters	650-1050
Mixers	250-400
Electric hair dryers	400-1600
microwaves	900-1300
Over-slab filters	250
Fans	1000-2000
Grill ovens	650-1350
Stationary electric stoves	8500-10500
Electric saunas	12000

For a home network with a voltage of 220 volts, the current value (in amperes, A) is determined by the following formula:

I=P/U,

where P is the electrical full load (presented in the table and also indicated in the technical data sheet of the device), W (watt);

U – voltage of the electrical network (in this case 220), V (volts).

If the network voltage is 380 volts, then the calculation formula is as follows:

I = P /√3× U= P /1.73× U,

where P is the total power consumption, W;

U — network voltage (380), V.

The permissible load for a copper cable is 10 A/mm², and for an aluminum cable it is 8 A/mm². To calculate, you need the resulting current value ( I) divided by 10 or 8 (depending on the selected conductor). The resulting value will be the approximate size of the required section.

Load calculation

At the initial stage, it is recommended to make an adjustment for the load. This was mentioned above, but let us repeat that situations rarely arise in everyday life when all energy consumers turn on at the same time. Most often, some devices work and others do not. Therefore, to clarify, the resulting cross-sectional value should be multiplied by the demand coefficient ( Ks). If you are sure that you will operate all devices at once, then you do not need to use the specified coefficient.

Table: Demand coefficients of various consumers (Kс).

Effect of conductor length

The length of the conductor is important when constructing industrial-scale networks, when the cable must be pulled over significant distances. During the passage of current through the wires, power losses (dU) occur, which are calculated using the following formula:

where I is the current strength;

p – resistivity (for copper - 0.0175, for aluminum - 0.0281);

L – cable length;

S – calculated cross-sectional area of ​​the conductor.

According to the technical specifications, the maximum voltage drop along the length of the wire should not exceed 5%. If the drop is significant, then you should choose a different cable. This can be done using tables, which already show the dependence of the amount of power and current on the cross-sectional area.

Table: Selection of wire for voltage 220 V.

Wire core cross-section, mm 2	Conductor core diameter, mm	Copper conductors		Aluminum conductors
		Current, A	Power, W	Current, A	power, kWt
0,50	0,80	6	1300
0,75	0,98	10	2200
1,00	1,13	14	3100
1,50	1,38	15	3300	10	2200
2,00	1,60	19	4200	14	3100
2,50	1,78	21	4600	16	3500
4,00	2,26	27	5900	21	4600
6,00	2,76	34	7500	26	5700
10,00	3,57	50	11000	38	8400
16,00	4,51	80	17600	55	12100
25,00	5,64	100	22000	65	14300

Calculation example

When planning the wiring diagram in the apartment, you first need to determine the places where the sockets and lighting fixtures will be located. It is necessary to determine which devices will be used and where. Next, you can draw up a general connection diagram and calculate the cable length. Based on the data obtained, the cable cross-sectional size is calculated using the formulas given above.

Suppose we need to determine the size of the cable to connect a washing machine. Let's take the power from the table - 2000 W and determine the current strength:

I=2000 W / 220 V=9.09 A (rounded to 9 A). To increase the safety margin, you can add a few amperes and select the appropriate cross-section depending on the type of conductor and installation method. For the example considered, a three-core cable with a copper core cross-section of 1.5 mm² is suitable.

Cross-section of conductor copper core, mm²	Permissible continuous load current, A	Maximum power of single-phase load for voltage 220 V, kW	Rated current of the circuit breaker, A	Maximum current of the circuit breaker, A	Possible consumers
1,5	19	4,1	10	16	lighting and alarm groups
2,5	27	5,9	16	25	socket groups and electric floors
4	38	8,3	25	32	water heaters and air conditioners
6	46	10,1	32	40	electric stoves and ovens
10	70	15,4	50	63	input supply lines

Calculation program cable 2.1

After familiarizing yourself with the calculation methodology and special tables, for convenience, you can use this program. It will save you from independent calculations and select the optimal cable cross-section according to the specified parameters.

There are two types of calculations in the cable 2.1 program:

1. Calculation of cross-section for a given power or current.
2. Calculation of maximum current and power by cross-section.

Let's look at each of them.

In the first case, you need to enter:

• Power value (in the example considered, 2 kW).
• Select the type of current, type of conductor, installation method and number of cores.
• By clicking the “Calculate” button, the program will display the required cross-section, current strength, recommended circuit breaker and residual current device (RCD).

Calculation of cross-section for a given power or current

In the second case, for a certain conductor cross-section, the program selects the maximum allowable:

• Power.
• Current strength.
• Recommended circuit breaker current.
• Recommended RCD.

Calculation of maximum current and power by cross section

As you can see, the calculator's interface is quite simple, and the end results are useful and informative.

No installation required. Open the archive and run the file “cable.exe”.

Video on this topic

A cable cannot carry more than a certain amount of current. When designing and installing electrical wiring in an apartment or house, select the correct conductor cross-section. This will allow you to avoid overheating of wires, short circuits and unplanned repairs in the future.

During the repair process, old electrical wiring is usually always replaced. This is due to the fact that recently many useful household appliances have appeared that make the life of housewives easier. Moreover, they consume a lot of energy, which old wiring simply cannot withstand. Such electrical appliances include washing machines, electric ovens, electric kettles, microwave ovens, etc.

When laying electrical wires, you should know what cross-section of wire needs to be laid in order to power a particular electrical appliance or group of electrical appliances. As a rule, the choice is made both by power consumption and by the current strength consumed by electrical appliances. In this case, you need to take into account both the laying method and the length of the wire.

It is quite simple to select the cross-section of the cable to be laid according to the load power. This can be a single load or a collection of loads.

Each household appliance, especially a new one, is accompanied by a document (passport), which indicates its basic technical data. In addition, the same data is available on special plates attached to the product body. This plate, which is located on the side or back of the device, indicates the country of manufacture, its serial number and, of course, its power consumption in watts (W) and the current that the device consumes in amperes (A). On products from domestic manufacturers, power may be indicated in watts (W) or kilowatts (kW). On imported models there is the letter W. In addition, the power consumption is designated as “TOT” or “TOT MAX”.

An example of such a plate showing basic information about the device. Such a plate can be found on any technical device.

If you cannot find out the necessary information (the inscription on the plate is worn out or there are no household appliances yet), you can find out approximately what power the most common household appliances have. All this data can actually be found in the table. Basically, electrical appliances are standardized in terms of power consumption and there is no particular variation in the data.

In the table, exactly those electrical appliances that you plan to purchase are selected, and their current consumption and power are recorded. From the list it is better to choose indicators that have maximum values. In this case, it will not be possible to miscalculate and the wiring will be more reliable. The fact is that the thicker the cable, the better, since the wiring heats up much less.

How the choice is made

When choosing a wire, you should sum up all the loads that will be connected to this wire. At the same time, you should ensure that all indicators are written out either in watts or kilowatts. To convert the indicators to one value, you should either divide the numbers or multiply by 1000. For example, to convert to watts, you should multiply all the numbers (if they are in kilowatts) by 1000: 1.5 kW = 1.5x1000 = 1500 W. When converting back, the actions are performed in the reverse order: 1500 W = 1500/1000 = 1.5 kW. Usually, all calculations are made in watts. After such calculations, a cable is selected using the appropriate table.

You can use the table as follows: find the corresponding column where the supply voltage is indicated (220 or 380 volts). This column contains a number that corresponds to the power consumption (you need to take a slightly higher value). In the line that corresponds to power consumption, the first column indicates the wire cross-section that can be used. When going to the store to buy a cable, you should look for a wire whose cross-section matches the notes.

Which wire to use - aluminum or copper?

In this case, everything depends on the power consumption. In addition, copper wire can withstand twice the load than aluminum wire. If the loads are large, then it is better to give preference to copper wire, as it will be thinner and easier to lay. In addition, it is easier to connect it to electrical equipment, including sockets and switches. Unfortunately, copper wire has a significant disadvantage: it costs much more than aluminum wire. Despite this, it will last much longer.

How to calculate cable cross-section by current

Most craftsmen calculate wire diameters based on current consumption. Sometimes this simplifies the task, especially if you know what current a wire of a particular thickness can withstand. To do this, you need to write down all the indicators of current consumption and sum them up. The wire cross-section can be selected using the same table, only now you need to look for the column where the current is indicated. As a rule, a larger value is always selected for reliability.

For example, to connect a hob, which can consume a maximum current of up to 16A, a copper wire must be selected. If you turn to the table for help, the desired result can be found in the third column on the left. Since there is no value 16A, we choose the nearest, larger one - 19A. A cable cross-section of 2.0 mm square is suitable for this current.

As a rule, when connecting powerful household appliances, they are powered by separate wires, with the installation of separate automatic switches. This greatly simplifies the process of selecting wires. In addition, this is part of modern electrical wiring requirements. Plus, it's practical. In an emergency, you do not have to turn off the electricity completely in your entire home.

It is not recommended to select wires with a lower value. If the cable constantly operates at maximum loads, this can lead to emergency situations in the electrical network. The result can be a fire if the circuit breakers are incorrectly selected. At the same time, you should know that they do not protect the wire sheath from fire, and it will not be possible to select the exact current so that it can protect the wires from overload. The fact is that they are not regulated and are issued at a fixed current value. For example, 6A, 10A, 16A, etc.

Choosing a wire with a reserve will allow you to install another electrical appliance or even several on this line in the future, if this corresponds to the current consumption rate.

Cable calculation by power and length

If we take into account the average apartment, the length of the wires does not reach such values ​​as to take this factor into account. Despite this, there are cases when when choosing wires, their length should be taken into account. For example, you need to connect a private house from the nearest pole, which may be located at a considerable distance from the house.

With significant current consumption, a long wire can affect the quality of power transmission. This is due to losses in the wire itself. The longer the wire, the greater the losses in the wire itself. In other words, the longer the wire, the greater the voltage drop in this section. In our time, when the quality of power supplies leaves much to be desired, this factor plays a significant role.

To know this, you will again have to refer to the table, where you can determine the cross-section of the wire, depending on the distance to the power point.

Table for determining wire thickness, depending on power and distance.

Open and closed method of laying wires

Current passing through a conductor causes it to heat up, since it has a certain resistance. So, the greater the current, the more heat is generated on it, under conditions of the same cross section. At the same current consumption, more heat is generated on conductors of smaller diameter than on conductors with a larger thickness.

Depending on the laying conditions, the amount of heat generated on the conductor also changes. When laying open, when the wire is actively cooled by air, you can give preference to a thinner wire, and when the wire is laid closed and its cooling is minimized, it is better to choose thicker wires.

Similar information can also be found in the table. The principle of selection is the same, but taking into account one more factor.

And finally, the most important thing. The fact is that nowadays the manufacturer is trying to save on everything, including the material for the wires. Very often, the declared cross-section does not correspond to reality. If the seller does not inform the buyer, then it is better to measure the wire thickness on the spot if this is critical. To do this, just take a caliper with you and measure the thickness of the wire in millimeters, and then calculate its cross-section using the simple formula 2*Pi*D or Pi*R squared. Where Pi is a constant number equal to 3.14, and D is the diameter of the wire. In another formula - respectively, Pi = 3.14, and R squared is the radius squared. The radius is very easy to calculate; just divide the diameter by 2.

Some sellers directly point out the discrepancy between the declared cross-section and the actual one. If the wire is chosen with a large margin, then this is not at all significant. The main problem is that the price of the wire, compared to its cross-section, is not underestimated.