Switching the automation of the home power network has been and remains the most important stage of electrical work. However, before proceeding with it, it is necessary to select the equipment in such a way that it can protect the wiring from overloads and short circuits. If all calculations are performed correctly, then the shutdown will occur when necessary, and not spontaneously. Although it is even worse if there is no cut-off at all - this is fraught with huge problems. In today's article, we will talk about how to choose a circuit breaker for power, current strength and other parameters of the electrical network.
Why protection is needed and how it works
If many consumers are connected to one outlet and the load on the wire exceeds the allowable one, the cable starts to heat up. This could ignite the insulation andfire. The same thing happens with a short circuit, but the heating process in this case proceeds rapidly, almost instantly. To prevent such emergencies, circuit breakers are installed, the features of the selection by power of which will be considered today.
Their job is as follows. Inside the AB is a static solenoid, through which current flows. A movable rod is located in the center of the coil. When an overcurrent occurs, a strong electromagnetic field is generated in the solenoid. It is it that pushes the rod, which presses on the foot, resulting in a cutoff. A bimetallic plate is responsible for turning off the voltage in case of overheating in the machine, which changes shape when the temperature rises.
Consequences of choosing the wrong assault rifle
Some home craftsmen who do not have experience in electrical work believe that it is better to purchase an AB of a higher denomination than to make the necessary calculations. This is a rather dangerous misconception that can lead to the loss of property or even life. The fact is that if you purchase an AB of a large denomination, without observing the rules for calculating circuit breakers, the following may happen. An overload on the line leads to heating of the wire, while the solenoid does not react to it. Further, the wire in the area of \u200b\u200bthe socket is heated to a critical temperature, the insulation ignites. Wallpaper and furniture light up from it. Burnt insulation, of course, leads to a short circuit and voltage cutoff, but thisthe action is already meaningless - the fire has already begun.
Now another, less terrible, but rather unpleasant mistake - the machine's face value is lower than required. When working on the line of one consumer, everything is in order, but if you turn on additionally, for example, a mixer or a food processor, a cut-off occurs, the voltage disappears. It is worth considering whether it will be comfortable to live in such conditions? Or is it easier to calculate everything correctly once?
How to make calculations correctly: first steps
Each electrical equipment consumes a certain amount of power. These data are contained on the nameplate of the household appliance and in its technical documentation. Before you calculate and select a circuit breaker, you need to write out the power consumption indicators of each of them on a piece of paper and add them up. It is on the basis of these data that calculations are made.
Let's make a similar calculation of the kitchen outlet group. For example, it is planned to connect a microwave oven (800 W), an electric kettle (1000 W), a dishwasher (2000 W) and a refrigerator (600 W). It turns out that the total consumption of the outlet group (P) will be equal to 4400 watts. But you need to choose the current circuit breaker. What if only the power consumption is known? It's not a problem. It is necessary to calculate the current load according to the formula I=P/U, where U is the voltage in the network. We get: 440 ÷ 220=20 A. In the line of manufactured machines there is just such a value, which means that an AB with a rated current of 20 A is perfect.
But these are not the only calculations that need to be made for the correct operation of the AB. Having chosen a circuit breaker in terms of power and current, you need to determine the wire section that is necessary for the normal power supply of household appliances connected through this socket group.
What could be wrong with wires
Quite a common situation: the new owner of the apartment is renovating. Sockets are changing, protective automation is selected ideally for installed household electrical appliances. However, subsequently the smell of burnt insulation appears, while the AB does not react in any way to heating (and therefore overload). Why is this happening? The problem is that the old wiring does not withstand the load that the machine is designed for. Here we should make a small digression.
The home master must understand that the circuit breaker is not designed to protect household appliances. Its task is to ensure the stable operation of the wiring. Therefore, when choosing an automatic machine for power, you should also decide on a cable that is suitable for the cross section. Only with full interaction of all nodes will the chain function normally.
Section selection and how to make it
For the correct selection of wires for this parameter, you should again refer to the total power consumption. In the example of a kitchen outlet group, this figure was 4400 watts. Now you need to turn to the section table - it can be easily found on the Internet. The closest value available in it is 4600 watts. Forpower devices of this power require a copper wire with a cross section of 2.5 mm2 or aluminum - 4 mm2. Only in this case can we hope that the machine will trip in case of overloads that are dangerous for the wire.
And from the video below you can learn a little more about the selection of AB.
What to do if it is not possible to replace the wires?
The question often arises of how to calculate and select a circuit breaker, leaving the old cables in place. In such a case, the only correct decision would be the selection of AB based on the cross section of the wire. This is the only way to be sure of safety. Then, when more consumers are plugged into the sockets than the cable can withstand, the protection will work.
In general, judging by user reviews, such problems are quite common. That is why people have to use the devices separately, of course, until the entire wiring is replaced.
Some tips on how to choose the right circuit breaker
Taking into account the fact that the number of household appliances is constantly growing, it is better to install the machine immediately with a little more power, but only on condition that the cables are also with an increased cross section. There are many “craftsmen” advisers on the Internet who say that if the machine can no longer withstand the increased load, you just need to put a more powerful device. In no case. After all, then the wiring it is intended to protect may not withstand.
How to choose a circuit breaker for a house, apartment? Liked in the storedevice should be carefully examined. Now quite a lot of falsified products have appeared on the shelves, the bulk of which can be easily identified visually.
How to recognize a fake
First of all, you should pay attention to the side wall of the machine. It has a rubber stopper that can be pulled out. A bimetallic plate will be visible under it. Those who produce fakes try not to invest in production, and therefore, instead of a rubber cork on the case, there will be a painted one, which cannot be opened. Naturally, there is no talk of any bimetallic plate inside. There is nothing at all, except for the switch. In fact, this is an ordinary switch that is not capable of any protection.
Also, before choosing a circuit breaker for power, current or cable cross-section, you should pay attention to its appearance. Should alert:
- foreign inclusions in the plastic case;
- uneven color, streaks;
- uneven seams;
- Fuzzy printed information on front side;
- large gaps between lever and body.
If such shortcomings are found, it is better to refrain from purchasing.
A little more about automation: some recommendations
Protecting your home electrical network is not limited to installing one AB. It should be understood that the load of the entire apartment should not go through onecircuit breaker. Of course, sometimes it seems that there is no other way out, especially for old houses. However, this is absolutely not the case. Entering the apartment and realizing that the protection system is no good, it is better to take care of this in the first place and replace the electrical wiring. Don't skimp on your safety. The algorithm of actions should be as follows.
To begin with, the wires leading to the apartment are completely disconnected from the introductory machine, and an extension cord is connected instead. Now you can not be afraid that when the walls are shredded, a short circuit will occur. After that, you can safely prepare channels for laying cables. To do this, you can use a conventional puncher or a special tool - an electric wall chaser.
After making the calculations, the necessary material is purchased - wires, AB (it is now known how to choose a circuit breaker for power). Power connection to the cables is made only after complete installation. Laying of live wires is not allowed. It is better to use copper cables for wiring. Despite the higher cost, they allow the use of a smaller section (and therefore easier to install). In addition, copper is much more durable than aluminum. There are cases when cheap wires crumbled after 10 years of operation.
If you plan to install household appliances with high power (electric stove, water heater), it is better for them to draw a separate line from the introductory machine.
Why the machine turns off for no reason
Similar, if such emergencies as overload and short circuit are excluded, can only occur because the AB has worked out the required cycles of operations. In this case, you will have to go to the store for a new one. Some argue that if you carefully open a failed AB, it is quite possible to restore it, but this should not be done. Today we talked about how to choose a circuit breaker for power. So, in the case of an attempt to repair an old AB, even if it was successful, you can forget about it. Such a "switch" (it can no longer be called an automatic machine) can fail at the most crucial moment.
In conclusion
Choosing a circuit breaker is a responsible matter. And the work of all the protective automation of the home electrical network, and hence the safety of property, and possibly life, will depend on how seriously the home master takes it.
