Calculation of cable thickness based on power. How to select the cable cross-section according to power? Calculation examples. How to calculate the cross-section of a stranded wire

Standard apartment wiring is calculated for a maximum current consumption at a continuous load of 25 amperes (the circuit breaker that is installed at the entrance of wires into the apartment is also selected for this current strength) and is carried out with copper wire with a cross-section of 4.0 mm 2, which corresponds to a wire diameter of 2.26 mm and load power up to 6 kW.

According to the requirements of clause 7.1.35 of the PUE the cross-section of the copper core for residential electrical wiring must be at least 2.5 mm 2, which corresponds to a conductor diameter of 1.8 mm and a load current of 16 A. Electrical appliances with a total power of up to 3.5 kW can be connected to such electrical wiring.

What is wire cross-section and how to determine it

To see the cross-section of the wire, just cut it across and look at the cut from the end. The cut area is the cross-section of the wire. The larger it is, the more current the wire can transmit.

As can be seen from the formula, the cross-section of the wire is light according to its diameter. It is enough to multiply the diameter of the wire core by itself and by 0.785. For the cross-section of a stranded wire, you need to calculate the cross-section of one core and multiply by their number.

The diameter of the conductor can be determined using a caliper with an accuracy of 0.1 mm or a micrometer with an accuracy of 0.01 mm. If there are no instruments at hand, then an ordinary ruler will help out.

Section selection
copper wire electrical wiring by current strength

The magnitude of the electric current is indicated by the letter “ A" and is measured in Amperes. When choosing, a simple rule applies: The larger the cross-section of the wire, the better, so the result is rounded up.

The data I have provided in the table is based on personal experience and guarantees reliable operation of electrical wiring under the most unfavorable conditions of its installation and operation. When choosing a wire cross-section based on the current value, it does not matter whether it is alternating current or direct current. The magnitude and frequency of the voltage in the electrical wiring also does not matter; it can be the on-board network of a DC car at 12 V or 24 V, an aircraft at 115 V with a frequency of 400 Hz, electrical wiring 220 V or 380 V with a frequency of 50 Hz, a high-voltage power line at 10,000 IN.

If the current consumption of an electrical appliance is not known, but the supply voltage and power are known, then the current can be calculated using the online calculator below.

It should be noted that at frequencies above 100 Hz, a skin effect begins to appear in wires when electric current flows, which means that with increasing frequency, the current begins to “press” against the outer surface of the wire and the actual cross-section of the wire decreases. Therefore, the choice of wire cross-section for high-frequency circuits is carried out according to different laws.

Determining the load capacity of 220 V electrical wiring
made of aluminum wire

In houses built a long time ago, electrical wiring is usually made of aluminum wires. If connections in junction boxes are made correctly, the service life of aluminum wiring can be one hundred years. After all, aluminum practically does not oxidize, and the service life of electrical wiring will be determined only by the service life of the plastic insulation and the reliability of the contacts at the connection points.

In the case of connecting additional energy-intensive electrical appliances in an apartment with aluminum wiring, it is necessary to determine by the cross-section or diameter of the wire cores its ability to withstand additional power. Using the table below, this is easy to do.

If your apartment wiring is made of aluminum wires and there is a need to connect a newly installed socket in a junction box with copper wires, then such a connection is made in accordance with the recommendations of the article Connecting aluminum wires.

Calculation of electrical wire cross-section
according to the power of connected electrical appliances

To select the cross-section of cable wire cores when laying electrical wiring in an apartment or house, you need to analyze the fleet of existing electrical household appliances from the point of view of their simultaneous use. The table provides a list of popular household electrical appliances indicating the current consumption depending on the power. You can find out the power consumption of your models yourself from the labels on the products themselves or data sheets; often the parameters are indicated on the packaging.

If the current consumed by an electrical appliance is not known, it can be measured using an ammeter.

Table of power consumption and current for household electrical appliances
at supply voltage 220 V

Typically, the power consumption of electrical appliances is indicated on the housing in watts (W or VA) or kilowatts (kW or kVA). 1 kW=1000 W.

Current is also consumed by the refrigerator, lighting fixtures, radiotelephone, chargers, and TV in standby mode. But in total this power is no more than 100 W and can be ignored in calculations.

If you turn on all the electrical appliances in the house at the same time, you will need to select a wire cross-section capable of passing a current of 160 A. You will need a finger-thick wire! But such a case is unlikely. It’s hard to imagine that someone is capable of grinding meat, ironing, vacuuming and drying hair at the same time.

Calculation example. You got up in the morning, turned on the electric kettle, microwave, toaster and coffee maker. The current consumption will accordingly be 7 A + 8 A + 3 A + 4 A = 22 A. Taking into account the switched on lighting, refrigerator and, in addition, for example, a TV, the current consumption can reach 25 A.

for 220 V network

You can select the wire cross-section not only by the current strength, but also by the amount of power consumed. To do this, you need to make a list of all electrical appliances planned to be connected to a given section of electrical wiring, and determine how much power each of them consumes separately. Next, add up the data obtained and use the table below.

If there are several electrical appliances and for some the current consumption is known, and for others the power, then you need to determine the wire cross-section for each of them from the tables, and then add up the results.

Selecting the cross-section of copper wire according to power
for the car's on-board network 12 V

If, when connecting additional equipment to the vehicle’s on-board network, only its power consumption is known, then the cross-section of the additional electrical wiring can be determined using the table below.

Selecting the wire cross-section for connecting electrical appliances
to a three-phase network 380 V

When operating electrical appliances, for example, an electric motor, connected to a three-phase network, the consumed current no longer flows through two wires, but through three and, therefore, the amount of current flowing in each individual wire is somewhat less. This allows you to use a smaller cross-section wire to connect electrical appliances to a three-phase network.

To connect electrical appliances to a three-phase network with a voltage of 380 V, for example an electric motor, the wire cross-section for each phase is taken 1.75 times smaller than for connecting to a single-phase 220 V network.

Attention, when choosing a wire cross-section for connecting an electric motor based on power, it should be taken into account that the nameplate of the electric motor indicates the maximum mechanical power that the motor can create on the shaft, and not the electrical power consumed. The electrical power consumed by the electric motor, taking into account efficiency and cos φ, is approximately two times greater than that created on the shaft, which must be taken into account when choosing the wire cross-section based on the motor power indicated in the plate.

For example, you need to connect an electric motor that consumes power from a 2.0 kW network. The total current consumption of an electric motor of such power in three phases is 5.2 A. According to the table, it turns out that a wire with a cross-section of 1.0 mm 2 is needed, taking into account the above 1.0 / 1.75 = 0.5 mm 2. Therefore, to connect a 2.0 kW electric motor to a three-phase 380 V network, you will need a three-core copper cable with a cross-section of each core of 0.5 mm 2.

It is much easier to choose the wire cross-section for connecting a three-phase motor based on the current consumption, which is always indicated on the nameplate. For example, in the nameplate shown in the photograph, the current consumption of a motor with a power of 0.25 kW for each phase at a supply voltage of 220 V (the motor windings are connected in a delta pattern) is 1.2 A, and at a voltage of 380 V (the motor windings are connected in a delta pattern) "star" circuit) is only 0.7 A. Taking the current indicated on the nameplate, using the table for selecting the wire cross-section for apartment wiring, select a wire with a cross-section of 0.35 mm 2 when connecting the electric motor windings according to the "triangle" or 0.15 mm pattern 2 when connected in a star configuration.

About choosing a cable brand for home wiring

Making apartment electrical wiring from aluminum wires at first glance seems cheaper, but operating costs due to low reliability of contacts over time will be many times higher than the costs of electrical wiring made from copper. I recommend making the wiring exclusively from copper wires! Aluminum wires are indispensable when laying overhead electrical wiring, as they are light and cheap and, when properly connected, serve reliably for a long time.

Which wire is better to use when installing electrical wiring, single-core or stranded? From the point of view of the ability to conduct current per unit of cross-section and installation, single-core is better. So for home wiring you only need to use solid wire. Stranded allows multiple bends, and the thinner the conductors in it, the more flexible and durable it is. Therefore, stranded wire is used to connect non-stationary electrical appliances to the electrical network, such as an electric hair dryer, an electric razor, an electric iron and all the others.

After deciding on the cross-section of the wire, the question arises about the brand of cable for electrical wiring. The choice here is not great and is represented by only a few brands of cables: PUNP, VVGng and NYM.

PUNP cable since 1990, in accordance with the decision of Glavgosenergonadzor “On the ban on the use of wires such as APVN, PPBN, PEN, PUNP, etc., produced according to TU 16-505. 610-74 instead of APV, APPV, PV and PPV wires according to GOST 6323-79*" is prohibited for use.

Cable VVG and VVGng - copper wires in double polyvinyl chloride insulation, flat shape. Designed for operation at ambient temperatures from −50°С to +50°С, for wiring inside buildings, outdoors, in the ground when laid in tubes. Service life up to 30 years. The letters “ng” in the brand designation indicate the non-flammability of the wire insulation. Two-, three- and four-core wires are available with core cross-sections from 1.5 to 35.0 mm 2 . If in the cable designation there is a letter A (AVVG) before VVG, then the conductors in the wire are aluminum.

The NYM cable (its Russian analogue is the VVG cable), with copper cores, round in shape, with non-flammable insulation, complies with the German standard VDE 0250. Technical characteristics and scope of application are almost the same as the VVG cable. Two-, three- and four-core wires are available with core cross-sections from 1.5 to 4.0 mm 2 .

As you can see, the choice for laying electrical wiring is not large and is determined depending on what shape the cable is more suitable for installation, round or flat. A round-shaped cable is more convenient to lay through walls, especially if the connection is made from the street into the room. You will need to drill a hole slightly larger than the diameter of the cable, and with a larger wall thickness this becomes relevant. For internal wiring, it is more convenient to use a VVG flat cable.

Parallel connection of electrical wiring wires

There are hopeless situations when you urgently need to lay wiring, but there is no wire of the required cross-section available. In this case, if there is a wire with a smaller cross-section than necessary, then the wiring can be made from two or more wires, connecting them in parallel. The main thing is that the sum of the sections of each of them is not less than the calculated one.

For example, there are three wires with a cross section of 2, 3 and 5 mm 2, but according to calculations, 10 mm 2 is needed. Connect them all in parallel and the wiring will handle up to 50 amps. Yes, you yourself have repeatedly seen the parallel connection of a large number of thin conductors to transmit large currents. For example, welding uses a current of up to 150 A and in order for the welder to control the electrode, a flexible wire is needed. It is made from hundreds of thin copper wires connected in parallel. In a car, the battery is also connected to the on-board network using the same flexible stranded wire, since when starting the engine, the starter consumes current from the battery up to 100 A. And when installing and removing the battery, the wires must be taken to the side, that is, the wire must be flexible enough .

The method of increasing the cross-section of an electrical wire by connecting several wires of different diameters in parallel can be used only as a last resort. When laying home electrical wiring, it is permissible to connect in parallel only wires of the same cross-section taken from the same reel.

Online calculators for calculating the cross-section and diameter of a wire

Using the online calculator presented below, you can solve the inverse problem - determine the diameter of the conductor by cross-section.

How to calculate the cross-section of a stranded wire

Stranded wire, or as it is also called stranded or flexible, is a single-core wire twisted together. To calculate the cross-section of a stranded wire, you must first calculate the cross-section of one wire, and then multiply the resulting result by their number.

Let's look at an example. There is a multi-core flexible wire, in which there are 15 cores with a diameter of 0.5 mm. The cross-section of one core is 0.5 mm × 0.5 mm × 0.785 = 0.19625 mm 2, after rounding we get 0.2 mm 2. Since we have 15 wires in the wire, to determine the cable cross-section we need to multiply these numbers. 0.2 mm 2 ×15=3 mm 2. It remains to determine from the table that such a stranded wire will withstand a current of 20 A.

You can estimate the load capacity of a stranded wire without measuring the diameter of an individual conductor by measuring the total diameter of all twisted wires. But since the wires are round, there are air gaps between them. To eliminate the gap area, you need to multiply the result of the wire cross-section obtained from the formula by a factor of 0.91. When measuring the diameter, you need to make sure that the stranded wire does not flatten.

Let's look at an example. As a result of measurements, the stranded wire has a diameter of 2.0 mm. Let's calculate its cross-section: 2.0 mm × 2.0 mm × 0.785 × 0.91 = 2.9 mm 2. Using the table (see below), we determine that this stranded wire will withstand a current of up to 20 A.

Often, before purchasing cable products, there is a need to independently measure its cross-section in order to avoid deception on the part of manufacturers, who, due to savings and setting a competitive price, may slightly underestimate this parameter.

It is also necessary to know how the cable cross-section is determined, for example, when adding a new energy-consuming point in rooms with old electrical wiring that does not have any technical information. Accordingly, the question of how to find out the cross-section of conductors always remains relevant.

General information about cable and wire

When working with conductors, it is necessary to understand their designation. There are wires and cables that differ from each other in their internal structure and technical characteristics. However, many people often confuse these concepts.

A wire is a conductor that has in its design one wire or a group of wires woven together and a thin common insulating layer. A cable is a core or a group of cores that has both its own insulation and a common insulating layer (sheath).

Each type of conductor will have its own methods for determining cross sections, which are almost similar.

Conductor materials

The amount of energy that a conductor transmits depends on a number of factors, the main one of which is the material of the current-carrying conductors. The following non-ferrous metals can be used as the core material of wires and cables:

1. Aluminum. Cheap and lightweight conductors, which is their advantage. They are characterized by such negative qualities as low electrical conductivity, a tendency to mechanical damage, high transient electrical resistance of oxidized surfaces;
2. Copper. The most popular conductors, which have a high cost compared to other options. However, they are characterized by low electrical and transition resistance at the contacts, fairly high elasticity and strength, and ease of soldering and welding;
3. Aluminum copper. Cable products with aluminum cores coated with copper. They are characterized by slightly lower electrical conductivity than their copper counterparts. They are also characterized by lightness, average resistance and relative cheapness.

Important! Some methods for determining the cross-section of cables and wires will depend specifically on the material of their conductor component, which directly affects the throughput power and current strength (method of determining the cross-section of conductors by power and current).

Measuring the cross-section of conductors by diameter

There are several ways to determine the cross-section of a cable or wire. The difference in determining the cross-sectional area of ​​wires and cables will be that in cable products it is necessary to measure each core separately and summarize the indicators.

For information. When measuring the parameter under consideration with instrumentation, it is necessary to initially measure the diameters of the conductive elements, preferably removing the insulating layer.

Instruments and measurement process

The measuring instruments can be a caliper or a micrometer. Mechanical devices are usually used, but electronic analogues with a digital screen can also be used.

Basically, the diameter of wires and cables is measured using a caliper, since it is found in almost every household. It can also measure the diameter of wires in a working network, for example, a socket or panel device.

The diameter of the wire cross-section is determined using the following formula:

S = (3.14/4)*D2, where D is the diameter of the wire.

If the cable contains more than one core, then it is necessary to measure the diameter and calculate the cross-section using the above formula for each of them, then combine the result obtained using the formula:

Stotal= S1 + S2 +…+Sn, where:

• Stotal – total cross-sectional area;
• S1, S2, …, Sn – cross sections of each core.

On a note. To ensure the accuracy of the results obtained, it is recommended to take measurements at least three times, turning the conductor in different directions. The result will be the average.

In the absence of a caliper or micrometer, the diameter of the conductor can be determined using a regular ruler. To do this, you need to perform the following manipulations:

1. Clean the insulating layer of the core;
2. Wind the turns around the pencil tightly to each other (there should be at least 15-17 pieces);
3. Measure the winding length;
4. Divide the resulting value by the number of turns.

Important! If the turns are not laid evenly on the pencil with gaps, then the accuracy of the obtained results of measuring the cable cross-section by diameter will be in doubt. To increase the accuracy of measurements, it is recommended to take measurements from different sides. It will be difficult to wind thick wires onto a simple pencil, so it is better to resort to a caliper.

After measuring the diameter, the cross-sectional area of ​​the wire is calculated using the formula described above or determined using a special table, where each diameter corresponds to the cross-sectional area.

It is better to measure the diameter of the wire, which contains ultra-thin cores, with a micrometer, since a caliper can easily break it.

The easiest way to determine the cable cross-section by diameter is using the table below.

Table of correspondence between wire diameter and wire cross-section

Segment cable cross-section

Cable products with a cross-section of up to 10 mm2 are almost always produced in a round shape. Such conductors are quite sufficient to meet the domestic needs of houses and apartments. However, with a larger cross-section of the cable, the input cores from the external electrical network can be made in segment (sector) form, and it will be quite difficult to determine the cross-section of the wire by diameter.

In such cases, it is necessary to resort to a table where the size (height, width) of the cable takes the corresponding value of the cross-sectional area. Initially, it is necessary to measure the height and width of the required segment with a ruler, after which the required parameter can be calculated by correlating the obtained data.

Table for calculating the area of ​​an electric cable core sector

Dependence of current, power and core cross-section

It is not enough to measure and calculate the cross-sectional area of ​​the cable based on the diameter of the core. Before installing wiring or other types of electrical networks, it is also necessary to know the capacity of the cable products.

When choosing a cable, you must be guided by several criteria:

• the strength of the electric current that the cable will pass;
• power consumed by energy sources;

Power

The most important parameter during electrical installation work (in particular, cable laying) is throughput. The maximum power of electricity transmitted through it depends on the cross-section of the conductor. Therefore, it is extremely important to know the total power of the energy consumption sources that will be connected to the wire.

Typically, manufacturers of household appliances, appliances and other electrical products indicate on the label and in the documentation accompanying them the maximum and average power consumption. For example, a washing machine can consume electricity ranging from tens of W/h during rinsing mode to 2.7 kW/h when heating water. Accordingly, a wire with a cross-section that is sufficient to transmit electricity of maximum power must be connected to it. If two or more consumers are connected to the cable, then the total power is determined by adding the limit values ​​of each of them.

The average power of all electrical appliances and lighting devices in an apartment rarely exceeds 7500 W for a single-phase network. Accordingly, the cable cross-sections in the electrical wiring must be selected to this value.

So, for a total power of 7.5 kW, it is necessary to use a copper cable with a core cross-section of 4 mm2, which is capable of transmitting about 8.3 kW. The cross-section of the conductor with an aluminum core in this case must be at least 6 mm2, passing a current power of 7.9 kW.

In individual residential buildings, a three-phase power supply system of 380 V is often used. However, most equipment is not designed for such electrical voltage. A voltage of 220 V is created by connecting them to the network through a neutral cable with an even distribution of the current load across all phases.

Electric current

Often the power of electrical equipment and equipment may not be known to the owner due to the absence of this characteristic in the documentation or completely lost documents and labels. There is only one way out in such a situation - to calculate using the formula yourself.

Power is determined by the formula:

P = U*I, where:

• P – power, measured in watts (W);
• I – electric current strength, measured in amperes (A);
• U is the applied electrical voltage, measured in volts (V).

When the strength of the electric current is unknown, it can be measured with control and measuring instruments: an ammeter, a multimeter, and a clamp meter.

After determining the power consumption and electric current, you can use the table below to find out the required cable cross-section.

Calculation of the cross-section of cable products based on current load must be carried out to further protect them from overheating. When too much electric current passes through conductors for their cross-section, destruction and melting of the insulating layer can occur.

The maximum permissible long-term current load is the quantitative value of the electric current that can pass the cable for a long time without overheating. To determine this indicator, it is initially necessary to sum up the powers of all energy consumers. After this, calculate the load using the formulas:

1. I = P∑*Ki/U (single-phase network),
2. I = P∑*Kи/(√3*U) (three-phase network), where:

• P∑ – total power of energy consumers;
• Ki – coefficient equal to 0.75;
• U – electrical voltage in the network.

Tablitz for matching the cross-sectional area of ​​copper conductorsconductor products current and power *

*Important! Conductors with aluminum conductors have different values.

Determining the cross-section of a cable product is a particularly important process in which miscalculations are unacceptable. You need to take into account all factors, parameters and rules, trusting only your calculations. The measurements taken must coincide with the tables described above - if they do not contain specific values, they can be found in the tables of many electrical engineering reference books.

Video

In electrical networks there are many parameters determined in various ways. Among them there is a special table; the diameter and cross-section of the wire are determined with high accuracy using it. Such precise data is required when adding an electrical load, and the old wire does not have letter markings. However, even conventional designations 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 measuring instruments are widely used, showing the most accurate results. Basically, the use of micrometers and calipers is practiced for these purposes. Despite their 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 the right approach, it becomes possible to measure the diameter of wire cores even on working lines. After obtaining the necessary data, all that remains is to use a special formula: The result of the calculation will be the area of ​​the circle, which is the cross-section of the wire or cable core.

Defining a section using a ruler

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

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 pressed tightly together, since free space contributes to a significant increase in the error in calculations. The error can be reduced by using a large number of measurements taken in different versions.

A significant disadvantage of this method is the ability to measure only relatively thin conductors. This is explained by the difficulties that arise when winding a thick cable. In addition, it is required to purchase a sample of the product 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 labor-intensive 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 clearly represents their relationship. 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 at the table and calculate the required cross-section.

When performing calculations, you must follow certain recommendations. 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 cores and a higher insulating layer. If there is any doubt about the size of the cable, 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 resulting values ​​are summed up and used in a formula or table.

Hello. The topic of today's article is “ Cable cross-section by power". This information will be useful both at home and at work. We will talk about how to calculate the cable cross-section by power and make a choice using a convenient table.

Why is it even necessary? choose the correct cable section?

In simple terms, this is necessary for the normal operation of everything related to electric current. Be it a hair dryer, washing machine, motor or transformer. Today, innovations have not yet reached the wireless transmission of electricity (I think they will not reach it soon); therefore, the main means for transmitting and distributing electric current are cables and wires.

With a small cable cross-section and high power equipment, the cable can heat up, which leads to loss of its properties and destruction of the insulation. This is not good, so correct calculation is necessary.

So, selection of cable cross-section by power. For selection we will use a convenient table:

The table is simple, I don’t think it’s worth describing it.

Let's say we have a house, we are installing closed electrical wiring using a VVG cable. Take a sheet of paper and copy down the list of equipment used. Done? Fine.

How to find out power? You can find the power on the equipment itself; there is usually a tag where the main characteristics are written down:

Power is measured in Watts (W, W), or Kilowatts (kW, KW). Found it? We record the data, then add it up.

Let's say you get 20,000 W, that's 20 kW. The figure tells us how much energy all electrical receivers consume together. Now you need to think about how many devices you will use simultaneously over a long period of time? Let's say 80%. The simultaneity coefficient in this case is 0.8. Let's do calculation of cable cross-section by power:

We count: 20 x 0.8 = 16(kW)

To do selection of cable cross-section according to power, look at our tables:

Correct selection of electrical cable is important in order to ensure an adequate level of safety, cost-effective use of the cable and full use of all the capabilities of the cable. A well-designed cross-section must be capable of operating at full load continuously without damage, withstanding short-circuits in the network, supplying the load with the appropriate current voltage (without excessive voltage drop) and ensuring the functionality of protective devices during ground faults. That is why a scrupulous and accurate calculation of the cable cross-section by power is carried out, which today can be done quite quickly using our online calculator.

Calculations are made individually using the formula for calculating the cable cross-section separately for each power cable for which you need to select a specific cross-section, or for a group of cables with similar characteristics. All methods for determining cable dimensions to one degree or another follow the main 6 points:

• Collecting data about the cable, its installation conditions, the load it will carry, etc.
• Determination of minimum cable size based on current calculation
• Determination of minimum cable size based on consideration of voltage drop
• Determination of minimum cable size based on increasing short circuit temperature
• Determination of minimum cable size based on loop impedance for insufficient grounding
• Selecting the largest cable sizes based on calculations in points 2, 3, 4 and 5

Online calculator for calculating cable cross-section by power

To use an online cable cross-section calculator, you need to collect the information necessary to perform sizing calculations. Typically, you need to obtain the following data:

• Detailed characteristics of the load that the cable will supply
• Cable purpose: for three-phase, single-phase or direct current
• System and/or source voltage
• Total load current in kW
• Total Load Power Factor
• Starting power factor
• Cable length from source to load
• Cable design
• Cable laying method

Copper and aluminum cable cross-section tables

When determining most calculation parameters, the cable cross-section calculation table presented on our website will be useful. Since the main parameters are calculated based on the needs of the current consumer, all the initial ones can be calculated quite easily. However, the brand of cable and wire, as well as an understanding of the cable design, also plays an important role.

The main characteristics of the cable design are:

• Conductor material
• Conductor Shape
• Conductor type
• Conductor Surface Coating
• Insulation type
• Number of cores

The current flowing through the cable creates heat due to losses in the conductors, losses in the dielectric due to thermal insulation and resistive losses from current. That is why the most basic thing is to calculate the load, which takes into account all the features of the power cable supply, including thermal ones. The parts that make up a cable (such as conductors, insulation, sheath, armor, etc.) must be able to withstand the temperature rise and heat emanating from the cable.

A cable's carrying capacity is the maximum current that can continuously flow through a cable without damaging the cable's insulation and other components. It is this parameter that is the result when calculating the load to determine the total cross-section.

Cables with larger conductor cross-sectional areas have lower resistance loss and can dissipate heat better than thinner cables. Therefore, a cable with a 16 mm2 cross-section will have a higher current carrying capacity than a 4 mm2 cable.

However, this difference in cross-section is a huge difference in cost, especially when it comes to copper wiring. That is why it is necessary to make a very accurate calculation of the power cross-section of the wire so that its supply is economically feasible.

For AC systems, the voltage drop calculation method is usually based on the load power factor. Generally, the full load currents are used, but if the load was high at start-up (eg a motor), then the voltage drop based on the starting current (power and power factor, if applicable) must also be calculated and taken into account, since the low voltage It is also the reason for the failure of expensive equipment, despite modern levels of its protection.

Video reviews on choosing cable cross-section

Use other online calculators.