Current consumption formula. Power of household electrical appliances. An example from the life of new settlers

It is useful for every electricity consumer to be able to calculate the load on household sockets installed in a house or apartment. According to regulatory document PEU - rules for electrical installations - each individual apartment has its own input with an electrical panel on which it is installed circuit breaker with current cut-off 25 A.

This is the maximum load current of all simultaneously switched on in the house household appliances. The only exception may be a separate input with its own circuit breaker for powering powerful loads of more than 2 kW, for example, a kitchen electric stove.

Energy-intensive household appliances

Today the industry produces powerful household electrical appliances, such as:

• electric kettles (up to 2 kW);
• washing machines (up to 3 kW);
• microwave ovens (up to 2.2 kW);
• dishwashers (up to 2 kW);
• meat grinders and food processors (up to 2.2 kW);
• grills and ovens (up to 2 kW);
• vacuum cleaners and irons (up to 2 kW),
• air conditioners and heaters (up to 3 kW).

Therefore, it is important for the consumer to know the capabilities of electrical outlets through which energy is supplied to ensure operation. household devices. In case of overload, you should expect unpleasant phenomena in the form of sparking and burning of contacts, melting of plastic elements and wire insulation, and the appearance of a burning smell.

Types of electrical outlets

All sockets installed in the apartment can be of three types. In old apartments, you can still find 6 A products. New European-style sockets are designed for a current of 10 A or 16 A. The contact elements of powerful products are made of thicker metal, have better spring properties, and provide reliable electrical connection, which means they are more durable in use.

Often the socket housings are not marked, and it is impossible to determine what current the installation device is designed for. In this case, during the next preventative repair, you need to ask a specialist about this. You should also inquire about the load capacity of the apartment wiring that supplies electrical energy to the sockets. The wire cross-section may not be sufficient to operate a 16-amp product, and this must be taken into account.

How to convert permissible current to power

When a consumer needs to connect many household appliances to one outlet, an extension cord with additional outlets is usually used. The extension cord must have a load current no less than that for which the original outlet is designed. When connecting loads to an extension cord, it is necessary that the total current does not exceed the capacity of the apartment outlet. Installation products are usually characterized by a rated current in amperes, which they are able to provide during long-term operation. Power household electrical appliances, as a rule, is given in watts. The problem arises of converting one unit of measurement into another.

The problem is solved using the Joule-Lenz law, which is formulated as follows: power is the product of current and voltage P = I x U. To recalculate permissible current sockets for permissible power, sufficient voltage household network 230 V (or 220 V) multiplied by rated current outlets (6, 10 or 16 amps). Having made the necessary calculations, we obtain the following results.

For a 230 V network:

• A value of 6 A corresponds to a permissible power of 1380 W.

• The value 10 A corresponds maximum power 2300 W.

• The value of 16 A corresponds to a maximum power of 3680 W.

For mains voltage 220 V:

• A value of 6 A corresponds to the highest power of 1320 W.

• A value of 10 A corresponds to a maximum power of 2200 W.

• A value of 16 A corresponds to the highest power of 3520 W.

Household voltage electrical network, used in your region depends on your country of residence. According to the international agreement IEC 38-83, 175 countries have currently switched to a single 230 V standard, including Russia, Armenia, Ukraine, and Estonia. The old 220 V rating is still used in Belarus, Latvia, Moldova, Kazakhstan, Georgia and other countries. Voltage in electrical outlet can be measured by an electrician using a voltmeter.

How to convert power consumption into current

The second method involves calculating the total load not in watts, but in amperes. To convert the rating data of a household appliance, given in power units, into consumed current, it is necessary to divide this value by the voltage of the electrical network.

Let's give an example. Let's say an electric kettle consumes 1.8 kW of power, that is, 1800 W. Dividing this value by 230 V, we obtain a rounded value of current consumption of 7.8 A. Another example will allow us to calculate the current consumption of a toaster per 1 kW. Having made similar calculations, we obtain a current of 4.3 A.

If the housewife turns on these two devices at the same time in the morning through an extension cord into a 10-amp outlet, then the total current (12.1 A) will exceed the maximum capability of the product, and it will begin to deteriorate. When using a 16-amp outlet, the undesirable situation will not occur.

An example from the life of new settlers

A young family with two children (4.5 years and 5 months) made an exchange and moved to a three-room apartment in a nine-story building built in the 80s from reinforced concrete panels with elevator.

The electrical equipment of the apartment is made without a common grounding circuit and PE conductor. An introductory switchboard is installed at each entrance. From him power cables disperse along the floor panels. On each floor there are 4 apartments from two blocks; right and left with a common corridor. It contains housing panels, which are powered by “aluminum noodles” of 2.5 mm2. The same wires are used for all electrical wiring in the rooms.

The new owner is a home craftsman who can not only hammer a nail, but also beautifully lay expensive tiles, repair plumbing, connect a washing machine/dishwasher, find faults in the phone and computer, and troubleshoot problems. software. But he is not an electrician, although he has repeatedly changed sockets and switches.

When checking the electrical wiring, the owner table lamp went through all the sockets and made sure they were in good working order. And I checked the lighting bulbs from the switches: they worked. He calmed down and got busy decorative finishing premises, and the problems began later.

In the fall, before the start of the heating season, heating was required in the children's room. We turned on an oil radiator with a power of 2 kW. At this time the washing machine and Dishwasher, two televisions, a refrigerator with a freezer, a computer, lighting, a radiotelephone and several low-power consumers.

There was a burning smell in the rooms electrical insulation. It came especially strongly from the common corridor from the apartment panel. I had to turn off the power supply from the apartment and figure it out: the overall picture from the electrician’s point of view looked depressing.

In the hallway, bathroom and living room there is suspended ceiling made of plasterboard sheets, blocking access to distribution boxes. The bedroom and children's room are covered with expensive ones decorative wallpaper, and the junction boxes are not only hidden under them, but also beautifully plastered. Their approximate location had to be clarified with the neighbors living on the ground floor. Expensive tiles on the walls and permanent fabric suspended ceiling completely block access to the wiring in the kitchen.

I had to contact electricians and technical reference books, analyze the situation. The apartment's aluminum wires were installed under the rated current load created by consumers thirty years ago. In addition, they have already served a decent amount of time:

aluminum was subjected to bending, stretching, crimping with screws, and in places of deformation its cross-section decreased;

polyvinyl chloride insulation was rubbed when pulled through the cavities reinforced concrete structures and experienced excessive heating from excessive currents during operation.

The most critical place turned out to be: where the neutral conductors were assembled. For these purposes it was used installation site in two parts. The first half received zero from the floor panel, and the second half collected all the other wires.

Between the platforms there was a jumper made of the same aluminum wire. The entire load of the apartment passed through it, like the incoming wire. The metal survived, but the insulation burned out over more than 2/3 of the length, starting from the first platform: the miscellaneous effects created by the screw clamps had an effect.

The insulation of the wire from the floor panel also began to melt, but not so intensely. The fire did not have time to occur - the electricity was turned off in time and the wires were allowed to cool.

On this moment in this apartment:

the defective jumper was replaced with a copper one capable of withstanding heavy loads;

The new owners were explained the rules for using electrical appliances and their attention was drawn to the inadmissibility of simultaneously turning on powerful electricity consumers.

After a long conversation, the home master:

seriously took up the study of electrical engineering and electrical installation rules: he plans to replace the electrical wiring with a more powerful one new scheme with a RE-conductor and collects money for the upcoming work;

contacted the housing and communal services regarding the transfer of the building to the power supply scheme according to TN-C-S system, but is not satisfied with the answer that this work is still planned: he is looking for alternative options for the apartment located on the fourth floor.

Rules for choosing electrical wiring

To avoid such mistakes for safe use With electricity, you need to know the rules for choosing electrical wiring. It is designed to withstand long-term current loads that arise when connecting consumers.

The more devices are plugged into sockets, the higher the load on the electrical circuit. In every specific case this value varies, but the maximum value is used to select the metal and wire cross-section.

In order to determine the maximum power consumption, it is recommended to make a table for all electrical receivers. Information should be taken from technical documentation or nameplates located on the device housing.

As an example, a table might have next view(although numerical values ​​may vary).

The list can be continued, but it will not be possible to provide for all possible purchases. Therefore, they make a small reserve of power, although it should be understood that all of the listed devices do not work at the same time.

The final information is summarized, but taking into account the creation of consumption groups by room. The results are entered into the prepared table.

Based on the calculations, a hierarchy is created electrical diagram apartments, in which not only wires are included, but also are selected taking into account the principle of selectivity protective devices, control devices, automation.

To determine the current load in the wire of each group, calculations are carried out using the formulas shown in the figure. For single-phase 220 V and three-phase 380 V circuits they differ by 1.732.

In these formulas, the index “P” denotes the received power electrical appliances for each group with a network voltage of 220 or 380 volts

The coefficient of simultaneous operation “CI” approximately takes into account the part of the disconnected devices, and cos φ with such an approximate estimate can be equated to unity: assuming that only the active component of power is consumed. Inductive and capacitive load, as well as transition processes when included, we neglect.

After determining the current values, you should refer to the PUE tables to select the material and cross-section of the conductor. They take into account operating conditions that create additional cooling/heating of the metal.

Table for selecting wire and cable cores based on current and transmitted power (click on the picture to enlarge):

It is likely that the current calculated from the power of consumers will not coincide with the table value. In this case, you should choose the larger of the two options in terms of value and select a section based on it.

Installation errors

Working with electrical wires, some electricians commit serious violations of existing rules:

the metal cores are often excessively compressed, scratches and cuts are made with a fitter’s knife, which are difficult to notice with the eye, but over time they lead to a break

insulation is subject to abrasion by drawing, cutting or exposure solar radiation.

Influence sun rays on polyvinyl chloride insulation electrical wires

Cables and wires can work reliably and for a long time: several decades, subject to technology. But the picture below shows the effect of solar radiation on a wire that was working on outdoors without any protection only 5 years. You cannot create such conditions for electrical appliances.

Concluding this article, I would like to turn to experienced electricians with a request: supplement the material with your recommendations from practical work. This will help home handyman who is interested in replacing the wiring in his apartment, do such work more efficiently.