Those who are at least a little versed in electrics should understand that the choice of circuit breakers is a responsible matter. In a simple way, they are called "automatic". For each such machine there is a maximum permissible load. It is equally important to pay attention to the cross section of the wires used.
If you plan to connect two or more electrical appliances to one cable, do not forget to sum their load. This will allow you to select a suitable cable section.
What are the machines for? They protect wiring from ignition and melting. For example, if the wiring starts to overheat, the machine will turn off the power. It will do this in the event of a short circuit as well.
To find out what load a particular machine can withstand, tables are used. They have helped me many times. But I know a couple of people who do not trust tables. They prefer to do the math themselves. If you are one of them, today's article will be very helpful.
Automatic machines of different amperage
I propose to discuss a single-phase network. It has 1 amp = 220 watts. For a 16A machine, the calculations are as follows: 16 x 220 = 3520 watts.
We round the resulting value to 3.5 kW. It turns out that the switch will not withstand more than 3.5 kW.
For other switches, calculations are carried out by analogy:
- 25A x 220 W = 5.5 kW;
- 32A x 220 W = 7 kW.
I think there is no need to explain that with the help of this formula you will calculate the allowable load for an automaton of any amperage.
Dealt with automatics. Let's now move on to a discussion of cables and choosing the right one. Please note that the load is transferred to the cable, corresponding to the load on the machine.
If you connect a cable that is too thin, the machine will not turn off when it is shorted or overheated. This is fraught with melting of the wiring and a short circuit. The worst outcome is a fire.
How to calculate cable power
I suggest not to do the calculations, but immediately turn to the tables. But if even here you want to calculate everything yourself, I will still write the formula.
It is generally accepted that 1mm2 of cable can withstand 10A. The calculation of the approximate load is as follows:
P = U x I (power = voltage X current).
From here we calculate the current: I = P/U.
To make it clearer, let me give you an example.
You have a 2.5 kW electric stove and you don't know which cable will fit it. Calculate the current using the formula above: 2500W/220W = 11.3A.
Let's say that 1mm of cable can withstand 10A. It turns out that for a plate of the specified power, a wire with a cross section of 1.5 mm2 is suitable.
Be sure to consider the load. The selected cable can only power the electric stove. If you decide to connect any other electrical appliance to it, the wiring will not stand it. Remember this!
Notice we didn't do any complex calculations? Everything is elementary, continuous multiplication and division. But even though the calculations are simple, you need to carefully choose machines and cables. If you do not calculate the load or do not look at it in the table, the consequences will be very unpleasant. In the best case - the melting of the wiring, in the worst - a fire. Be careful with electrical matters!
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