In the modern technological world, electricity has almost become on the same level of importance as water and air. It is used in almost any area of human activity. The concept of electricity appeared back in 1600; before that, we knew about electricity no more than the ancient Greeks. But over time, it began to spread more widely, and only in 1920 did it begin to replace kerosene lamps as street lighting. Since then, electric current began to spread rapidly, and now it is available even in the most remote village, at least illuminating the house and for telephone communications.
Electricity itself is a stream of directed charges moving along a conductor. A conductor is a substance capable of passing these electric charges through itself, but each conductor there is resistance(except for the so-called superconductors, the resistance of superconductors is zero, this state is achievable by lowering the temperature to -273.4 degrees Celsius).
How to understand the cross-sections of copper and aluminum cables for wiring?
This article is intended to teach you how to calculate the cross-section of a wire. It's like the more water you want to supply, the larger the diameter of the pipe you need. So here, the greater the electrical current consumption, the larger the cross-section of cables and wires should be. I will briefly describe what it is: if you bite through a cable or wire and look at it from the end, you will see its cross-section, that is, the thickness of the wire, which determines the power that this wire is capable of transmitting when heated to the permissible temperature.
In order to select the correct cross-section of the power wire, we it is necessary to take into account the maximum value of the current load consumed. The current values can be determined by knowing the rated power of the consumer, which is determined by the following formula: I=P/220, where P is the power of the current consumer, and 220 is the number of volts in your outlet. Accordingly, if the outlet is 110 or 380 volts, then we substitute this value.
It is important to know that the calculation of the value for single-phase and three-phase networks is different. In order to find out how many phases of the network you need, you need to calculate the total amount of current consumption in your home. Let's give an example of the average set of equipment that you may have at home.
A simple example of calculating cable cross-section based on current consumption, now we will calculate the sum of the powers of connected electrical appliances. The main consumers in an average apartment are the following devices:
- TV - 160 W
- Refrigerator - 300 W
- Lighting - 500 W
- Personal computer - 550 W
- Vacuum cleaner - 600 W
- Microwave oven - 700 W
- Electric kettle - 1150 W
- Iron - 1750 W
- Boiler (water heater) - 1950 W
- Washing machine - 2650 W
- Total 10310 W = 10.3 kW.
Once we know the total electricity consumption, we can use the formula to calculate the cross-section of the wire for the normal functioning of the wiring. It's important to remember that for single-phase and three-phase networks the formulas will be different.
Calculation of wire cross-section for a network with one phase (single-phase)
The wire cross-section is calculated using the following formula:
I = (P × K u) / (U × cos(φ))
- P- power of all energy consumers in total
- K and- simultaneity coefficient, as a rule, the generally accepted value for calculations is 0.75
- U- phase voltage, which is 220V but can range from 210V to 240V.
- cos(φ)- for household single-phase appliances this value is fixed and equals 1.
I- current strength;
When we have found the current consumption according to the formula, we can start choosing a cable, which suits us in terms of power. Or rather, its cross-sectional area. Below is a special table that provides data that compares the current value, cable cross-section and power consumption.
Data may vary for wires made of different metals. Today, for residential applications, copper, rigid cable is typically used. Aluminum cable is practically not used. But still, in many older houses, aluminum cable is still present.
Table of estimated cable current capacity. The choice of copper cable cross-section is made according to the following parameters:
We also provide a table for calculating the current consumption of an aluminum cable:
If the power value turns out to be an average between two indicators, then you need to select a larger wire cross-section value. Since there must be a power reserve.
Calculation of the wire cross-section of a network with three phases (three-phase)
Now let’s look at the formula for calculating the wire cross-section for three-phase networks.
To calculate the cross-section of the supply cable, we use the following formula:
I = P / (√3 × U × cos(φ))
- I- current strength by which the cross-sectional area of the cable is selected
- U- phase voltage, 220V
- Cosφ - phase angle
- P- shows the total consumption of all electrical appliances
Cosφ- in the above formula is extremely important, since it personally affects the current strength. It varies for different equipment; this parameter can most often be found in the technical documentation, or the corresponding marking on the case.
The total power is found very simply, we sum up the value of all power indicators and use the resulting number in the calculations.
A distinctive feature in a three-phase network is that a thinner wire can withstand a larger load. We select the required wire cross-section according to the table below.
Calculation of wire cross-section by current consumption used in a three-phase network is used using such a value as √3 . This value is needed to simplify the appearance of the formula itself:
U linear = √3 × U phase
In this way, if the need arises, the product of the root and phase voltage is replaced by the linear voltage. This value is equal to 380V (U linear = 380V).
Concept of continuous current
Also, one equally important point when choosing a cable for a three-phase and single-phase network is that it is necessary to take into account a concept that sounds like permissible long-term current. This parameter shows us the current strength in the cable that the wire can withstand for an unlimited amount of time. You can define the ego in a special table. They also differ significantly for aluminum and copper conductors.
When this parameter exceeds the permissible values, the conductor begins to overheat. The heating temperature is inversely proportional to the current strength.
Temperatures may increase in some areas not only due to incorrectly selected wire cross-section, and also with poor contact. For example, in the place where wires are twisted. This quite often happens at the point of contact between copper cables and aluminum cables. In this regard, the surface of the metals undergoes oxidation, becoming covered with an oxide film, which greatly impairs the contact. In such a place the cable will heat up above the permissible temperature.
When we have carried out all the calculations and checked the data from the tables, you can safely go to a specialized store and buy the cables you need for laying a network at home or in the country. Your main advantage over, for example, your neighbor will be that you have fully understood this issue with the help of our article, and you will save a lot of money without overpaying for what the store wanted to sell you. Yes, and knowing how to calculate the current cross-section for copper or aluminum wires will never be superfluous, and we are sure that the knowledge gained from us will come in handy many times on your life’s journey.
Each electrical network, regardless of its purpose, must withstand the electrical load connected to it for a long time. Both household electrical appliances and industrial electrical equipment can be used as a load.
Household and industrial consumers
Household electrical appliances and devices include lamps, electric kettles, vacuum cleaners, boilers, heaters, personal computers, printers, scanners, TVs, washing machines, kitchen appliances, etc.
Industrial electrical equipment includes electric motors, relays, starters, contactors, power transformers, industrial lighting, etc.
Each device, device and equipment consumes a certain amount of electricity during operation. The amount of consumption depends on the rated and operating power of the device, device or equipment.
Rated power of the electrical product
The unit of power measurement is indicated in watts or kilowatts. The rated power value is indicated either in the passport of the electrical product or on the product itself.
If this is a household appliance, for example, a kettle, then the rated power consumption can be indicated on a special sticker. For a boiler, the power is indicated in the passport. And for a regular incandescent lamp, the rated power value is marked on the lamp bulb and on the cardboard packaging.
If this is an electric motor for industrial use, then the power (and not only power) is indicated on a nameplate (a special metal plate) attached to the motor housing. For power transformers, the power is also indicated on the nameplate.
Calculation of the cross-section of an electrical cable or wire
To correctly select the electrical conductor through which voltage will be supplied to electrical consumers, it is necessary to know the total number of consumers themselves, the rated power of each consumer, as well as the list of consumers that will operate simultaneously. Knowing all this, it will be possible to select a conductor cross-section at which the electrical network will be able to withstand the load connected to it.
Electrical network conductors can be divided into two groups. The first group is the common (input) cable or wire. The second group is outgoing lines.
Initially, the cross-section of the input electrical cable is selected. Because Since the entire load will pass through the input cable, its cross-section should be larger than that of the outgoing conductors. As for the outgoing conductors, the cross-section will depend on the power and number of connected consumers.
Section calculation stages
Household consumers
Let’s say the following consumers will be in the apartment:
- lighting (5 incandescent lamps of 100 watts each, 5 incandescent lamps of 75 watts each, 2 incandescent lamps of 65 watts each, one fluorescent lamp of 80 watts);
- 100 watt TV;
- boiler with a capacity of 2 kilowatts;
- electric fireplace with a capacity of 1.5 kilowatts;
- personal computer with a power of 450 watts;
- 100 watt refrigerator;
- electric kettle with a power of 1.5 kilowatts.
We convert the power values of all consumers into kilowatts and summarize:
5*0.1kW + 5*0.075kW + 2*0.065kW + 0.080kW + 0.1kW + 2kW + 1.5kW + 0.45kW + 0.1kW + 1.5kW = 6.735kW.
It turns out that the total installed power of consumers in the apartment is almost 7 kW. If you look at the table of cross-sections and powers for copper wires in a single-phase 220V network, then for a value of 6.735 kW you can select the standard cross-section of the input common wire or cable 4mm 2 or 2.5mm 2. A cross section of 4 mm 2 in a single-phase network is 8.3 kW. Those. when using this section there will be a power reserve.
As for the 2.5 mm 2 section, this section corresponds to a power of 5.9 kW. Those. even less than the installed capacity. However, a cross section of 2.5 mm 2 can be chosen if in the future the power of simultaneously operating electrical consumers will not exceed 5.9 kW.
Industrial users
Let’s say the following three-phase consumers are located in the production area:
- three-phase electric motor with a power of 5 kW;
- three-phase power transformer with a power of 100 kW (although the power of the power transformer is usually indicated in kVA);
- work lighting with three groups with a total power of 3 kW.
We calculate the total power by adding the power of the electric motor, power transformer and working lighting power. We get 5kW + 100kW + 3kW = 108kW. According to the table, for a load of 108 kW, an electric cable with a core cross-section of 70 mm 2 is suitable. For this section, the maximum three-phase load is 118.8 kW. Those. and in this case, the 70mm 2 section has a power reserve.
Above are the calculations for a common electrical cable. As for outgoing wires and cables, the calculations are carried out similarly. Just keep in mind that there are usually several outgoing conductors and each may have its own separate load.
Sometimes, to select a section, they do not resort to detailed calculations and selection of the section from the table. In practice, in a household electrical network (wiring), a copper wire with a cross-section of 2.5 mm 2 is chosen for outlet circuits, and a copper wire with a cross-section of 1.5 mm 2 is chosen for lighting circuits. As for production, calculations of the cross-section of wires and electrical cables are mandatory.
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:
- 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;
- 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;
- 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:
- Clean the insulating layer of the core;
- Wind the turns around the pencil tightly to each other (there should be at least 15-17 pieces);
- Measure the winding length;
- 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
| Diameter of conductor element, mm | Cross-sectional area of the conductor element, mm2 |
|---|---|
| 0,8 | 0,5 |
| 0,9 | 0,63 |
| 1 | 0,75 |
| 1,1 | 0,95 |
| 1,2 | 1,13 |
| 1,3 | 1,33 |
| 1,4 | 1,53 |
| 1,5 | 1,77 |
| 1,6 | 2 |
| 1,8 | 2,54 |
| 2 | 3,14 |
| 2,2 | 3,8 |
| 2,3 | 4,15 |
| 2,5 | 4,91 |
| 2,6 | 5,31 |
| 2,8 | 6,15 |
| 3 | 7,06 |
| 3,2 | 7,99 |
| 3,4 | 9,02 |
| 3,6 | 10,11 |
| 4 | 12,48 |
| 4,5 | 15,79 |
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
| Cable type | Sectional area of the segment, mm2 | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| S | 35 | 50 | 70 | 95 | 120 | 150 | 185 | 240 | |
| Four-core segment | V | - | 7 | 8,2 | 9,6 | 10,8 | 12 | 13,2 | - |
| w | - | 10 | 12 | 14,1 | 16 | 18 | 18 | - | |
| Three-core segmental stranded, 6(10) | V | 6 | 7 | 9 | 10 | 11 | 12 | 13,2 | 15,2 |
| w | 10 | 12 | 14 | 16 | 18 | 20 | 22 | 25 | |
| Three-core segmental single-wire, 6(10) | V | 5,5 | 6,4 | 7,6 | 9 | 10,1 | 11,3 | 12,5 | 14,4 |
| w | 9,2 | 10,5 | 12,5 | 15 | 16,6 | 18,4 | 20,7 | 23,8 | |
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 when rinsing 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:
- I = P∑*Ki/U (single-phase network),
- 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 *
| Section of cable and wire products | Electrical voltage 220 V | Electrical voltage 380 V | ||
|---|---|---|---|---|
| Current strength, A | power, kWt | Current strength, A | power, kWt | |
| 2,5 | 27 | 5,9 | 25 | 16,5 |
| 4 | 38 | 8,3 | 30 | 19,8 |
| 6 | 50 | 11 | 40 | 26,4 |
| 10 | 70 | 15,4 | 50 | 33 |
| 16 | 90 | 19,8 | 75 | 49,5 |
| 25 | 115 | 25,3 | 90 | 59,4 |
| 35 | 140 | 30,8 | 115 | 75,9 |
| 50 | 175 | 38,5 | 145 | 95,7 |
| 70 | 215 | 47,3 | 180 | 118,8 |
| 95 | 260 | 57,2 | 220 | 145,2 |
| 120 | 300 | 66 | 260 | 171,6 |
*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
The quality of electrical installation work affects the safety of the entire building. The determining factor when carrying out such work is the cable cross-section. To carry out the calculation, you need to find out the characteristics of all connected electricity consumers. It is necessary to calculate the cable cross-section based on power. The table is needed to see the required indicators.
A high-quality and suitable cable ensures safe and durable operation of any network
The optimal cross-sectional area of the cable allows the maximum amount of current to flow without heating up. When carrying out an electrical wiring project, it is important to find the correct value for the wire diameter that would suit the specific power consumption conditions. To perform the calculations, you need to determine the total current. In this case, you need to find out the power of all equipment that is connected to the cable.
Before work, the wire cross-section and load are calculated. The table will help you find these values. For a standard 220 volt network, the approximate current value is calculated as follows: I(current)=(P1+P2+….+Pn)/220, Pn – power. For example, the optimal current for an aluminum wire is 8 A/mm, and for a copper wire is 10 A/mm.
The table shows how to carry out calculations, knowing the technical characteristicsLoad calculation
Even having determined the desired value, you can make certain adjustments for the load. After all, it’s not often that all devices work simultaneously on the network. To make the data more accurate, it is necessary to multiply the cross-sectional value by Kc (correction factor). If all equipment is turned on at the same time, then this coefficient does not apply.
To perform calculations correctly, use the table for calculating cable cross-section by power. It should be taken into account that there are two types of this parameter: reactive and active.
An alternating current flows in electrical networks, the indicator of which can change. Active power is needed to calculate the average. Electric heaters and incandescent lamps have active power. If there are electric motors and transformers in the network, then some deviations may occur. At the same time, reactive power is generated. In calculations, the reactive load indicator is reflected as a coefficient (cosф).
Helpful information! In everyday life, the average cosph value is 0.8. But for a computer this figure is 0.6-0.7.
Calculation by length
Calculations of parameters along the length are necessary when constructing production lines, when the cable is subjected to heavy loads. For calculations, use a table of cable cross-sections for power and current. When current moves along highways, power losses appear, which depend on the resistance appearing in the circuit.
According to technical parameters, the largest voltage drop should not be more than five percent.
Using a table of wire cross-sections by power
In practice, a table is used to carry out calculations. Calculation of the cable cross-section for power is carried out taking into account the shown dependence of the current and power parameters on the cross-section. There are special standards for the construction of electrical installations, where you can view information on the required measurements. The table shows common values.
To select a cable for a certain load, you need to make some calculations:
- calculate the current strength indicator;
- round to the highest using the table;
- select the closest standard parameter.
Related article:
Important information! Most manufacturers reduce the section size to save material. Therefore, when making a purchase, use a caliper and measure the wire yourself, and then calculate the area. This will avoid problems with overload. If the wire consists of several twisted elements, then you need to measure the cross-section of one element and multiply by their number.
What are some examples?
A specific diagram will allow you to make the right choice of cable cross-section for your apartment. First of all, plan the places where the light sources and sockets will be placed. You should also find out which equipment will be connected to each group. This will allow you to draw up a plan for connecting all elements, as well as calculate the length of the wiring. Don't forget to add 2 cm at the joints of the wires.
Determination of wire cross-section taking into account different types of load
Using the obtained values, the current value is calculated using formulas and the cross section is determined from the table. For example, you need to find out the wire cross-section for a household appliance whose power is 2400 W. We calculate: I = 2400/220 = 10.91 A. After rounding, 11 A remains.
To determine the exact cross-sectional area, different coefficients are used. These values are especially relevant for a 380 V network. To increase the safety margin, it is worth adding another 5 A to the obtained indicator.
It is worth considering that three-core wires are used for apartments. Using the tables, you can select the closest current value and the corresponding wire cross-section. You can see what wire cross-section is needed for 3 kW, as well as for other values.
Wires of different types have their own calculation subtleties. Three-phase current is used where equipment of significant power is needed. For example, this is used for production purposes.
To identify the necessary parameters in production, it is important to accurately calculate all coefficients, as well as take into account power losses due to voltage fluctuations. When performing electrical work at home, you do not need to carry out complex calculations.
You should be aware of the differences between aluminum and copper wire. The copper version has a higher price, but at the same time surpasses its analogue in technical characteristics. Aluminum products can crumble on bends, and also oxidize and have a lower thermal conductivity. For safety reasons, only copper products are used in residential buildings.
Basic cable materials
Since alternating current moves through three channels, a three-core cable is used for installation work. When installing acoustic devices, cables with a minimum resistance value are used. This will help improve signal quality and eliminate possible interference. To connect such structures, wires are used, the size of which is 2 * 15 or 2 * 25.
Some average values will help you select the optimal cross-sectional indicator for everyday use. For sockets it is worth purchasing a 2.5 mm2 cable, and for lighting design – 1.5 mm2. Equipment with higher power requires a cross-section size of 4-6 mm2.
A special table will help if you have any doubts during the calculations. To determine accurate indicators, you need to take into account all the factors that influence the current in the circuit. These are the length of individual sections, installation method, type of insulation and permissible overheating value. All data helps to increase productivity on a production scale and use electrical energy more efficiently.
Calculation of cable and wire cross-section by power and current for connecting a private house (video)
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Every master wants to know... how to calculate the cable cross-section for a particular load. You have to deal with this when wiring in a house or garage, even when connecting machines - you need to be sure that the selected power cord will not smoke when you turn on the machine...
I decided to create a calculator for calculating cable cross-section by power, i.e. The calculator calculates the current consumed, and then determines the required wire cross-section, and also recommends the closest circuit breaker.
Power cables GOST 31996-2012
Calculation of the cable cross-section by power is carried out in accordance with the tables of the normative document GOST 31996-2012 “Power cables with plastic insulation”. In this case, the cross-section is indicated with a current reserve to avoid heating and fire of the wire operating at the maximum current. I also introduced a coefficient of 10%, i.e. another 10% is added to the maximum current for smooth operation of the cable :)
For example, we take a load power of 7000 W at a voltage of 250 Volts, we get a current of 30.8 Amps (adding 10% in reserve), we will use a single-core copper wire laid through the air, as a result we get a cross-section: 4 sq. mm., i.e. cable with a maximum current of 39 Amps. Cable with a cross section of 2.5 sq. mm. It is not recommended to use it for a current of 30 Amps, because the wire will be operated at the maximum permissible current values, which can lead to heating of the wire with subsequent destruction of the electrical insulation.
Table of cable cross-section by current and power for copper wire
Also check out these articles
| Core cross-section mm 2 | For cable with copper conductors | |||
|---|---|---|---|---|
| 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 | 33,0 |
| 16 | 85 | 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 | 260 | 57,2 | 220 | 145,2 |
| 120 | 300 | 66 | 260 | 171,6 |
The data in the tables is given for OPEN wiring!!!
Table of aluminum wire cross-section by power consumption and current
| Core cross-section mm 2 | For cable with aluminum conductors | |||
|---|---|---|---|---|
| Voltage 220 V | Voltage 380 V | |||
| Current A | Power, kWt | Current A | Power, kWt | |
| 2,5 | 20 | 4,4 | 19 | 12,5 |
| 4 | 28 | 6,1 | 23 | 15,1 |
| 6 | 36 | 7,9 | 30 | 19,8 |
| 10 | 50 | 11 | 39 | 25,7 |
| 16 | 60 | 13,2 | 55 | 36,3 |
| 25 | 85 | 18,7 | 70 | 46,2 |
| 35 | 100 | 22 | 85 | 56,1 |
| 50 | 135 | 29,7 | 110 | 72,6 |
| 70 | 165 | 36,3 | 140 | 92,4 |
| 95 | 200 | 44,0 | 170 | 112,2 |
| 120 | 230 | 50,6 | 200 | 132,0 |
Cable cross section calculator
The online calculator is designed to calculate the cable cross-section by power.
You can select the required electrical appliances by ticking them to automatically determine their power, or enter the power in watts (not kilowatts!) in the field below, then select the remaining data: network voltage, conductor metal, cable type, where it is laid and the calculator will calculate the wire cross-section by power and tell you which circuit breaker to install.
I hope my calculator will help many craftsmen.
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