Any electrical circuit in an apartment or house must be protected by a circuit breaker against overloads and short circuit overcurrents. This simple truth can be clearly demonstrated in any electrical panel of an apartment, floor panel, input distribution panel of a house, etc. electrical cabinets and boxes.
The question is not whether to install a circuit breaker or not, the question is how to calculate the circuit breaker so that it correctly performs its tasks, works when needed and does not interfere with the stable operation of electrical appliances.
Examples of circuit breaker calculations
You can read the theory of circuit breaker calculations in the article:. Here are some practical examples of calculating circuit breakers in the electrical circuit of a house or apartment.
Example 1. Calculation of the introductory machine at home
Let's start with examples of calculating circuit breakers from a private house, namely, we will calculate the input circuit breaker. Initial data:
- Network voltage Un = 0.4 kV;
- Estimated power Рр = 80 kW;
- Power factor COSφ = 0.84;
1st calculation:
To select the rating of the circuit breaker, we consider the load current rating of a given electrical network:
Iр = Рр / (√3 × Un × COSφ) Iр = 80 / (√3 × 0.4 × 0.84) = 137 A
2nd calculation
To avoid false tripping of the circuit breaker, the rated current of the circuit breaker (thermal release current) should be selected 10% more than the planned load current:
- I current of the release = Iр × 1.1
- It.r = 137 × 1.1 = 150 A
Calculation result: Based on the calculations made, we select a circuit breaker (according to PUE-85 clause 3.1.10) with the release current closest to the calculated value:
- I rated = 150 Ampere (150 A).
This choice of circuit breaker will allow the electrical circuit of the house to operate stably in operating mode and only operate in emergency situations.
Example 2. Calculation of a kitchen group circuit breaker
In the second example, we will calculate which circuit breaker should be chosen for the kitchen electrical wiring, which is correctly called the kitchen electrical wiring socket. It could be the kitchen of an apartment or a house, it makes no difference.
Similar to the first example, the calculation consists of two calculations: calculation of the load current of the kitchen electrical circuit and calculation of the thermal release current.
Load current calculation
Initial data:
- Mains voltage Un = 220 V;
- Estimated power Рр = 6 kW;
- Power factor COSφ = 1;
That is, if the kitchen has 10 sockets for 10 household appliances (stationary and portable), you need to take into account that all 10 appliances will not work at the same time.
Usage rate
- Write down the planned household appliances on a piece of paper.
- Next to the device, place its power according to its passport.
- Sum up all the power of the devices according to the passport. This Calculation.
- Think about what appliances can work simultaneously: kettle + toaster, microwave + blender, kettle + microwave + toaster, etc.
- Calculate the total powers of these groups. Calculate the average total power of groups of simultaneously switched on devices. It will be Pnominal(rated power).
- Divide Calculation on Pnominal, get the kitchen utilization rate.
In fact, in the theory of calculations, the utilization factor inside the house (without utility networks) and apartment is assumed to be equal to one if the number of sockets is no more than 10. This is true, but in practice, it is the utilization factor that allows modern kitchen household appliances to operate on old electrical wiring.
Note:
In the theory of calculations, 1 household outlet is planned for 6 sq. meters of apartment (house). Wherein:
- utilization factor = 0.7 – for sockets from 50 pcs.;
- utilization factor = 0.8 – sockets 20-49 pcs.;
- utilization factor = 0.9 – sockets from 9 to 19 pcs.;
- utilization factor=1.0 – sockets ≤10pcs.
Let's go back to the kitchen circuit breaker. We calculate the kitchen load current rating:
- Iр = Рр / 220V;
- Iр = 6000 / 220 = 27.3 A.
Release current:
- Icalc.= Iр×1.1=27.3×1.1=30A
According to the calculations made, we choose 32 Amperes for the kitchen.
Conclusion
The given example of calculating a kitchen turned out to be somewhat overestimated; usually 16 amperes are enough if you consider that the stove, washing machine, and dishwasher are put into separate groups.
These examples of calculating circuit breakers for group circuits only show the general principle of calculations, and do not include the calculation of engineering circuits including the operation of pumps, machines and other motors of a private house.
Photo gallery of circuit breakers
It is impossible to imagine the modern world without electricity. Every home has a variety of appliances, and people sometimes don’t even think about how much power all the devices and devices connected to the power grid consume.
Household appliances have become so integral to people's lives that as soon as a device breaks down, a person begins to get nervous, and some even panic.
Since there are usually many different devices operating in an apartment or house, the uninterrupted operation of a computer, refrigerator or TV and other devices often leads to exceeding the permissible standards in electrical networks, and as a result, a short circuit occurs.
Purpose of circuit breakers
In order to prevent such a situation, there are automatic switches. The most common and well-proven switches are ABB switches. A 16 amp machine is usually installed indoors. Such switches are produced in the form of modules, due to which they can be freely mounted in the required quantity and in the right place.
It is best to use special DIN rails designed for mounting switches on them. Anyone, even someone who is not very knowledgeable about electrical engineering, can install such switches. The only thing you need is to choose the correct rating of the device you are using.
Among other things, if necessary, it can be supplemented with various remote shutdown sensors, operation indicators, etc., which will ultimately make the use of the electrical installation more comfortable and durable.
When the electricity suddenly turns off in a house or apartment, they begin to look for the reason. And it often lies in exceeding the permissible load on the network. In other words, many more electrical appliances are connected to the sockets than were calculated during construction, or than were allocated for a specific consumer.
So how can you determine what load the machine will withstand at the entrance to a house or apartment, or at a separate consumption group? There are a few simple rules, and if you follow them, problems with power outages should not arise. And it doesn’t matter which machine is used - 16 amperes or 25, etc.
How machines are mistakenly chosen
In practice, they usually choose an automatic machine without much thought. Many are based on the required load, namely, they try to install such a machine so that it simply does not turn off under heavy load. So, for example, if 5 kW is required, then they install a 25 A machine, if there is a 3 kW load - a 16 amp machine, and so on. But this approach is completely ill-considered, since it will only lead to equipment breakdown or, even worse, to an electrical fire or even a fire.
This is why it was invented to protect against overload. This is for protection, not decoration of the electrical panel.
Operating principle of circuit breaker
The AB is designed to protect from overload all devices connected in the electrical circuit directly after it.
If it is chosen incorrectly, it will not work properly. So, for example, if you use an electric cable that is designed for 4-5 amperes and run 20-30 amperes through it, then such a machine will not turn off immediately, but will wait until the insulation melts and a short circuit occurs. Then it will turn off. But this is not what proper operation of the circuit breaker should lead to. Therefore, it is important to consider in advance, when installing a 16-amp machine, how many kW it will withstand in the presence of wires of a certain cross-section and maximum operating load.
Ideally, it should turn off as soon as it senses an overload. Then the wires will remain in order and the connected equipment will not burn out.
Choosing the right machine
How can you understand how many kilowatts a 16-amp machine can withstand in practice?
The most common correct way to select a circuit breaker is:
- determine the wire cross-section
- according to the rules of electrical installations, find the current that is permissible for such a wire cross-section
- select the machine that suits these parameters
For example, there is a copper wire with a cross section of 1.5 sq. mm. The current allowed for it is a maximum of 18-19 amperes. Accordingly, according to the rules, you need to choose a suitable machine, but with a downward shift according to the table. And this turns out to be 16 amperes. That is, you can install a 16 amp machine.
If the wire is copper and its cross-section is 2.5 sq. mm, then only a current of up to 26-27 amperes is allowed. Therefore, the maximum you can use is a 25-amp machine. Although, for reasons of reliability, it is better to install a 20-amp machine.
In this way, the parameters of the required machine for the remaining wire sections are calculated.
When using, you can select machines in the same way, only increase the cross-section not smaller, but larger.
Example: for an aluminum wire with a cross-section of 4 sq. mm, the permissible current is the same as for a copper wire with a cross-section of 2.5 sq. mm. And for the same wire, but made of aluminum, - as for 10 mm sq. copper The 6 mm one is the same as the 4 mm copper one. Further - similarly.
Types of slot machines
When choosing a circuit breaker, it is very important to study all the characteristics of the device. It is also necessary to carefully calculate the total power of all devices that are supposed to be connected to each group of machines. Not only the speed of operation of the switch, but also the quality of its operation will depend on these factors.
Most often, both in everyday life and in production, 16A machines are found. They are usually installed in electrical panels. Therefore, the question of how much a 16-amp machine can withstand is always relevant.
Features of switches
Circuit breakers are made of materials that are completely harmless to human health. Self-extinguishing thermoplastic is used in the manufacture of the device body. It is able to withstand very high temperatures. Its contacts are made of copper plates, silver plated for better contact and durability.
The design of the circuit breaker contains a special thermal relay, which is activated when the current flow exceeds the norm, and the electrical circuit opens without causing a short circuit. The higher the current indicator, the faster the operation speed of the machine. The count goes on in fractions of a second.
The scope of use of automatic switches is very extensive and extends from their installation in incoming electrical panels to distribution boards of apartments or houses. To use circuit breakers, special ones are produced with already installed DIN rails for the required number of circuit breakers. The buyer only needs to choose the one that meets his wishes and install the shield in the apartment or house.
Despite the apparent simplicity of using circuit breakers, it is better to entrust the connection of a 16-amp circuit breaker to a specialist.
In terms of rated current, circuit breakers differ both in current strength (rated from 1A to 6300A) and in the load on the circuit (220V, 380 and 400V). In addition, switches are usually distinguished by their response speed.
When designing electrical wiring in a room, you need to start by calculating the current strength in the circuits. An error in this calculation can be costly later. An electrical outlet can melt if exposed to too much current. If the current in the cable is greater than the calculated current for a given material and core cross-section, the wiring will overheat, which can lead to melting of the wire, a break or short circuit in the network with unpleasant consequences, among which the need to completely replace the electrical wiring is not the worst thing.
It is also necessary to know the current strength in the circuit to select circuit breakers, which should provide adequate protection against network overload. If the machine is set with a large margin at its nominal value, by the time it is triggered, the equipment may already be out of order. But if the rated current of the circuit breaker is less than the current that appears in the network during peak loads, the circuit breaker will drive you crazy, constantly cutting off power to the room when you turn on the iron or kettle.
Formula for calculating the power of electric current
According to Ohm's law, current (I) is proportional to voltage (U) and inversely proportional to resistance (R), and power (P) is calculated as the product of voltage and current. Based on this, the current in the network section is calculated: I = P/U.
In real conditions, one more component is added to the formula and the formula for a single-phase network takes the form:
and for a three-phase network: I = P/(1.73*U*cos φ),
where U for a three-phase network is assumed to be 380 V, cos φ is the power factor, reflecting the ratio of the active and reactive components of the load resistance.
For modern power supplies, the reactive component is insignificant; the value of cos φ can be taken equal to 0.95. The exception is powerful transformers (for example, welding machines) and electric motors; they have high inductive reactance. In networks where it is planned to connect such devices, the maximum current should be calculated using a cos φ coefficient of 0.8, or the current should be calculated using the standard method, and then a multiplying factor of 0.95/0.8 = 1.19 should be applied.
Substituting the effective voltage values of 220 V/380 V and a power factor of 0.95, we obtain I = P/209 for a single-phase network and I = P/624 for a three-phase network, that is, in a three-phase network with the same load, the current is three times less. There is no paradox here, since three-phase wiring provides three phase wires, and with a uniform load on each phase it is divided into three. Since the voltage between each phase and working neutral wires is 220 V, the formula can be rewritten in another form, so it is more clear: I = P/(3*220*cos φ).
Selecting the rating of the circuit breaker
Applying the formula I = P/209, we find that with a load with a power of 1 kW, the current in a single-phase network will be 4.78 A. The voltage in our networks is not always exactly 220 V, so it would not be a big mistake to calculate the current strength with a small margin like 5 A for every kilowatt of load. It is immediately clear that it is not recommended to connect an iron with a power of 1.5 kW to an extension cord marked “5 A”, since the current will be one and a half times higher than the rated value. You can also immediately “graduate” the standard ratings of the machines and determine what load they are designed for:
- 6 A – 1.2 kW;
- 8 A – 1.6 kW;
- 10 A – 2 kW;
- 16 A – 3.2 kW;
- 20 A – 4 kW;
- 25 A – 5 kW;
- 32 A – 6.4 kW;
- 40 A – 8 kW;
- 50 A – 10 kW;
- 63 A – 12.6 kW;
- 80 A – 16 kW;
- 100 A – 20 kW.
Using the “5 amperes per kilowatt” technique, you can estimate the current strength that appears in the network when connecting household devices. You are interested in peak loads on the network, so for the calculation you should use the maximum power consumption, not the average. This information is contained in the product documentation. It is hardly worth calculating this indicator yourself by summing up the rated powers of the compressors, electric motors and heating elements included in the device, since there is also such an indicator as the efficiency factor, which will have to be assessed speculatively with the risk of making a big mistake.
When designing electrical wiring in an apartment or country house, the composition and passport data of the electrical equipment that will be connected are not always known for certain, but you can use the approximate data of electrical appliances common in our everyday life:
- electric sauna (12 kW) - 60 A;
- electric stove (10 kW) - 50 A;
- hob (8 kW) - 40 A;
- instantaneous electric water heater (6 kW) - 30 A;
- dishwasher (2.5 kW) - 12.5 A;
- washing machine (2.5 kW) - 12.5 A;
- Jacuzzi (2.5 kW) - 12.5 A;
- air conditioner (2.4 kW) - 12 A;
- Microwave oven (2.2 kW) - 11 A;
- storage electric water heater (2 kW) - 10 A;
- electric kettle (1.8 kW) - 9 A;
- iron (1.6 kW) - 8 A;
- solarium (1.5 kW) - 7.5 A;
- vacuum cleaner (1.4 kW) - 7 A;
- meat grinder (1.1 kW) - 5.5 A;
- toaster (1 kW) - 5 A;
- coffee maker (1 kW) - 5 A;
- hair dryer (1 kW) - 5 A;
- desktop computer (0.5 kW) - 2.5 A;
- refrigerator (0.4 kW) - 2 A.
The power consumption of lighting devices and consumer electronics is small; in general, the total power of lighting devices can be estimated at 1.5 kW and a 10 A circuit breaker is sufficient for a lighting group. Consumer electronics are connected to the same outlets as irons; it is not practical to reserve additional power for them.
If you sum up all these currents, the figure turns out to be impressive. In practice, the possibility of connecting the load is limited by the amount of allocated electrical power; for apartments with an electric stove in modern houses it is 10 -12 kW and at the apartment input there is a machine with a nominal value of 50 A. And these 12 kW must be distributed, taking into account the fact that the most powerful consumers concentrated in the kitchen and bathroom. Wiring will cause less cause for concern if it is divided into a sufficient number of groups, each with its own machine. For the electric stove (hob), a separate input with a 40 A automatic circuit breaker is made and a power outlet with a rated current of 40 A is installed; nothing else needs to be connected there. A separate group is made for the washing machine and other bathroom equipment, with a machine of the appropriate rating. This group is usually protected by an RCD with a rated current 15% greater than the rating of the circuit breaker. Separate groups are allocated for lighting and for wall sockets in each room.
You will have to spend some time calculating powers and currents, but you can be sure that the work will not be in vain. Well-designed and high-quality electrical wiring is the key to the comfort and safety of your home.
Automatic switches are necessary to protect electrical wiring from overloads and short circuits (further referred to as short circuits). In the event of an emergency in the electrical network, an overcurrent may pass through the wiring in the house, in which case the cable insulation will instantly melt, and the electrical wiring itself will sparkle like sparklers.
It is clear that the result can be very disastrous. To avoid such unpleasant situations, you definitely need an automatic switch in the electrical panel (or better yet, several at once). We will try to tell you in this article how to select a machine based on cable cross-section, current and other technical characteristics.
So, when choosing a circuit breaker for your home, you need to pay attention to its main parameters.
Short circuit current
To select a circuit breaker based on an indicator such as short-circuit current, one important condition must be taken into account - the PUE rules prohibit the use of circuit breakers with a maximum breaking capacity of less than 6 kA. Today on the market you can find devices with denominations of 3; 4.5; 6 and 10 kA. So, if your home is located in close proximity to a transformer substation, then it is worth purchasing a 10 kA machine. In other cases, using a 6 kA machine will be quite sufficient.
Operating current (nominal)
Rated current is an equally important criterion in choosing a circuit breaker for your home. This indicator indicates the current value, above which the electrical circuit will disconnect. When choosing a suitable value (10, 16, 32, 40A, etc.), you need to pay attention to two main indicators: the power of electricity consumers in the house and the cross-section of the wiring cable. The operating current of the machine will directly depend on the largest current the electrical wiring can pass through.
In this case, you should first find out the cross-section of the cable in the room and only after that, using special tables, select a circuit breaker that is suitable for its characteristics.
Table for calculating the required cable cross-section Operating current
Along with the rated current of the circuit breaker, it is necessary to select its rating according to the tripping current. When turning on particularly powerful devices, the starting current can exceed the rated current by 12 times. That is why, so that the circuit breaker does not trip, mistaking the electrical connection for a short circuit, you should select the correct class of circuit breaker. For domestic use, classes D, C and B are used. For an apartment or house where there is a gas stove in the kitchen, it is better to choose a class B appliance. If you have an electric stove or a powerful electric boiler, you need to choose a class C or D machine.
Selectivity
The concept of selectivity is the shutdown of only a certain section in an emergency. At the same time, other areas will work. In this case, you need to understand a little of the logical chain and select the AB ratings according to the service line. At the top of the wiring branch there must be an input AB, the rating of which must be less than or equal to the maximum permissible load on the wiring, according to the cable cross-section.
The operating current of the input switching device must be higher than the rated current of all lower-level circuit breakers in the electrical panel. For an apartment or private house, devices with the following values will be optimal: input - 40A, electric stove - 32A, lighting - 10A, sockets - 16A, electrical appliances up to 5 kW - 25A. By choosing this option for assembling the switchboard, the necessary selectivity condition will be achieved.
Number of poles
The number of poles is another important criterion for selecting an AB. With him, usually, the least difficulties arise. So, for a regular single-phase 220 Volt network, a single-phase, two-pole circuit breaker should be installed at the input. Separately connected household appliances and lighting must be equipped with a suitable single-pole circuit breaker. If you have a three-phase electrical network in your apartment or house, then you should purchase a four-pole switching device for input.
Manufacturer
It is very important to choose the right circuit breaker manufacturer. Otherwise, you risk purchasing a fake. In such devices, the declared characteristics very often do not correspond to the actual parameters of the machines. Therefore, it is worth purchasing switching devices exclusively from trusted companies.
Unacceptable mistakes when choosing a machine
There are several main mistakes you can make when choosing a circuit breaker. If you select the wrong automatic protective equipment, the AV may be triggered when you turn on the household appliance. In addition, the service life will be less than stated, but the worst thing is that the electrical wiring may not withstand it.
To prevent such problems from occurring, let’s consider the most common mistakes when choosing circuit breakers for your home:
- First of all, you need to focus on the electrical wiring in the house, and not on the power of household appliances. So, if you purchase a 32A device to protect an electric boiler, and the cable cross-section can only withstand a current of 16A, then the electrical wiring will not withstand it and will simply melt. If you need to choose a powerful device for protection, then, first of all, you will need to replace the wiring in your home with a more powerful one.
- When calculating the rated current of an AV based on the rated current, the average value very often comes out, for example, 13.6A (not 16A and not 10A). In this case, you need to give preference to a higher indicator only when you are absolutely sure that your wiring can withstand a current load of 16A.
- For garages and cottages, it is worth choosing an AV with more power, since powerful spring pumps, asynchronous motors, welding machines, etc. can be used there. It is necessary to provide for the connection of very powerful consumers in advance, so as not to waste money on purchasing a more powerful switching device in the future. Usually, a 40A circuit breaker is quite sufficient for such needs.
- It is advisable to purchase devices from one, trusted company. In this case, the possibility of non-compliance can be reduced to zero.
- You should give preference only to specialized stores, or better yet, official distributors. They do not have counterfeits, and the cost of goods from a direct supplier is most often lower than that of an intermediary.
You may also be interested
Why change the machine?
Any electrician will say: “If there is no urgent need, it is better not to get into the electrical wiring of the house with your own hands.” The consequences can be dire. When does such a need arise?
In order to change the socket, you need to know physics in grades 8-9. With other electrical components, everything is a little more complicated. If a circuit breaker in your apartment regularly trips (the circuit breaker in the panel) and the light goes out, it’s time to change it.
Probably, the circuit breaker has exhausted its service life, even though the period specified in the passport has not yet expired. A worn-out 16 A device may operate at low load on the network (10 A), or may not operate at extreme values (contacts will be soldered together, and then there will be a fire).
Just in case, let us recall some information from the school curriculum:
- Power = Voltage x Current.
- Current = Power\Voltage.
The voltage in the socket is 220 V. The coffee maker indicates 1200 W, which means the current consumption will be 1200\220 = 5.45 (A).
If you managed to add up the power of all household electrical appliances and calculate the total current, you can consider yourself a second-level electrician.
How does the machine work and what does it protect against?
Externally, the circuit breaker is a plastic box for connecting wiring, plus a toggle switch. There is no need to go inside. It is important for us that it contains contacts, thermal and electromagnetic releases, which are responsible for de-energizing the network under increased and extreme loads.
How to decipher the markings on a circuit breaker:
- The letter (A, B, C, D) is the class of the machine; it means the limit of the instantaneous operation current, that is, the voltage when the machine immediately de-energizes the network in the apartment. In most cases, in residential buildings there will be a machine with the letter C. It will instantly operate at a 5-10 times increase in current from the nominal value. That is, a machine with a rating of 10 A will turn off the network without delay at a current value of 50-100 A. A machine with a B-characteristic (3-5 times the excess) will do the same at a value of 30-50 A.
- The number indicates the rated current, that is, the value up to which the machine will operate in normal mode without turning anything off. The same 10 A circuit breaker, if the current exceeds 11.5, will work only after two hours. At 14.5 it will wait a minute, if the network overvoltage does not disappear, it will de-energize the apartment. And so on, until the peak values indicated by the letter, when the network drops without delay.
- Next to it, in a smaller font, there will be another number (in thousands of amperes), indicating the maximum current value at which the machine will operate without being damaged.
What is the trick here, why can’t you immediately turn off the network if the nominal value is exceeded? The machine takes into account short-term currents that occur in the network for a split second when electrical equipment is turned on. When you turn on the washing machine, the starting current may be 2-3 times higher than the rated current.
The main function of a circuit breaker is to protect the network from short circuits and overloads. When too much current flows through a line, the wiring becomes hot. If this happens for too long, the wire may catch fire.
By and large, the machine doesn’t care about your electrical appliances; contrary to popular belief, it does not protect them from power surges. But losing a microwave or kettle connected to an outlet is one thing, but burnt out wiring in a wall or chandelier is another.
It is important to understand that the machine will not protect you from electric shock if you accidentally touch live areas or grounded objects. For this purpose, there are residual current devices (RCDs). It is advised to place one general one after the introductory machine and for groups where there is a risk of electric shock.
How to choose a machine for electrical wiring
In order to choose the right circuit breaker, you need to estimate the maximum permissible current load of the network (sum up all devices). The denomination of the machine (the number after the letter) should not exceed this value.
For an ordinary apartment where there are no “serious” power consumers such as an air conditioner, a class B machine is suitable. Such a network is considered lightly loaded. It is dangerous to install a high-load circuit breaker (class D) for a network that powers light bulbs. He will not perceive voltage surges in it as harmful and can even miss a short circuit.
A lightly loaded device in a network with a heavy load in normal mode, on the contrary, will operate inappropriately and often.
Yes, we almost missed it: machines differ in the number of phases (poles). The number of poles of the machine indicates which type of network it can work with. You can also install one class C input switch and one single-phase switch in the apartment to provide separate areas (kitchen, room, separately for air conditioning, if provided). If you don’t want to complicate things, in a two-room apartment you can get by with one circuit breaker B with a rating of 16.
We have almost figured out how to choose a circuit breaker based on current and power. But if you consider only the load of consumers, you can run into trouble. The choice of machine directly depends on the type of wiring and cable. If the wiring is weak, a powerful automatic machine will not cope with its tasks when overloaded. That is, you always need to take into account the cross-section of the wire and its throughput.
In houses before 2001-2003, there will most likely be aluminum wiring in single-layer insulation. Most likely, it has already served its purpose (nominally it can withstand 20 years under ideal conditions, without overload). It is categorically not recommended to install a new machine on it, taking into account only the total power of consumers. The automatic machine will stop working frequently, but the problem of overheating will remain.
There are essentially two options:
- Change the wiring to copper.
- For powerful consumers (washing machine, boiler, air conditioner), draw a separate line from the panel and install a separate machine on it.
Copper wire carries more current than aluminum wire. But here, in addition to the material, it is important to take into account its cross-section. It lets you know how many amps can be passed through the cable without fear of damage or overheating.
For example:
- Aluminum wire with a cross-section of 2.5 mm2 safely operates with currents up to 16-24 A.
- Copper wire with a cross-section of 2.5 mm2 safely operates with currents of 21-30 A.
This means that with a load of 23 A, it will de-energize the wiring in a minute. It is enough to prevent the copper wire from overheating. If you install, before disconnecting, the cable will carry current beyond its normal load, it will overheat, the insulation will wear out faster, and the socket will burn out over time. For aluminum wiring, accordingly, these values are lower.
For ease of understanding, we offer a table for selecting a circuit breaker based on the cable cross-section.
Last piece of advice: you shouldn’t skimp on your safety. It is better to buy machines from specialized stores and choose manufacturers with a proven reputation. On-site managers will answer questions that we may have missed in this article.
