Calculation of current strength and selection of power cable for mains voltage 220 and 380 V

To ensure safety in the operation of household appliances, it is necessary to correctly calculate the cross section of the power cable and wiring. Because an incorrectly selected cable core cross section creates a risk of ignition wiring due to a short circuit. This threatens to cause a fire in the building. This also applies to the choice of cable for connecting electric motors.

current calculation

The amount of current is calculated by power and required at the design stage (planning) housing - apartments, houses.

• The choice of power cable depends on the value of this value (wire), which can be used to connect electricity appliances to the grid.
• Knowing the mains voltage and the full load of electrical appliances, you can calculate the current strength by the formula, which will need to be passed through the conductor (wire, cable). According to its size, choose the cross-sectional area of ​​the veins.

If known consumers in the apartment or house, it is necessary to perform simple calculations, to properly mount the power supply circuit.

Similar calculations are performed for production purposes: determining the required cross-sectional area of ​​the cable cores when connecting industrial equipment (various industrial electric motors and mechanisms).

Single-phase mains voltage 220 V

Current strength I (in amperes, A) calculated by the formula:

I = P / U,

where P is the electric full load (must be specified in the technical data sheet of the device), W (watts);

U - mains voltage, V (volt).

The table below shows the load values ​​of typical household appliances and the current consumed by them (for voltage 220 V).

Electrical appliance	Power consumption, W	Amperage, A
Washing machine	2000 — 2500	9,0 — 11,4
jacuzzi	2000 — 2500	9,0 — 11,4
electric floor heating	800 — 1400	3,6 — 6,4
Stationary electric stove	4500 — 8500	20,5 — 38,6
Microwave oven	900 — 1300	4,1 — 5,9
Dishwashers	2000 — 2500	9,0 — 11,4
Freezers, refrigerators	140 — 300	0,6 — 1,4
Electric meat grinder	1100 — 1200	5,0 — 5,5
electric kettle	1850 — 2000	8,4 — 9,0
electric coffee maker	6з0 - 1200	3,0 — 5,5
Squeezer	240 — 360	1,1 — 1,6
toaster	640 — 1100	2,9 — 5,0
mixer	250 — 400	1,1 — 1,8
hair dryer	400 — 1600	1,8 — 7,3
iron	900 — 1700	4,1 — 7,7
Vacuum cleaner	680 — 1400	3,1 — 6,4
fan	250 — 400	1,0 — 1,8
TV	125 — 180	0,6 — 0,8
radio equipment	70 — 100	0,3 — 0,5
lighting devices	20 — 100	0,1 — 0,4

The figure shows ??the scheme of the device of power supply of the apartment at single-phase connection to a network with voltage 220 V.

As can be seen from the figure, various consumers of electricity are connected through appropriate machines to electricity meters and then to the general machine, which must be designed to load the devices, what the apartment will be equipped with. Wire, supplying power must also meet the load of energy consumers.

Below is a table for concealed wiring with a single-phase connection diagram of the apartment for the selection of wires at voltage 220 V

Intersection of wire wires, mm2	The diameter of the conductor core, mm	copper cores		aluminum cores
		Current, A	Power, W	Current, A	Power, kw
0,50	0,80	6	1300
0,75	0,98	10	2200
1,00	1,13	14	3100
1,50	1,38	15	3300	10	2200
2,00	1,60	19	4200	14	3100
2,50	1,78	21	4600	16	3500
4,00	2,26	27	5900	21	4600
6,00	2,76	34	7500	26	5700
10,00	3,57	50	11000	38	8400
16,00	4,51	80	17600	55	12100
25,00	5,64	100	22000	65	14300

As can be seen from the table, the cross section of the veins depends not only on the load but also on the material, of which the wire is made.