6 important criteria for choosing a circuit breaker
Key selection criteria
- Short circuit current. To choose a short circuit current circuit breaker, an important condition must be taken into account - according to the rules of the PUE, machines with the highest breaking capacity of less than 6 kA are prohibited. Today, devices can have ratings of 3; 4,5; 6 and 10 kA. If your house is located next to a transformer substation, you need to choose a circuit breaker that operates at the limit short circuit at 10 kA. In other cases, it is quite enough to choose a switching device with a nominal value of 6000 Amer.
- Rated current (working). The next, no less important criterion for choosing a machine for the house is by rated current. This characteristic displays the value of the current above which the circuit will disconnect and, accordingly, protect the wiring from overloads. In order to choose a suitable value (it can be 10, 16, 32, 40A, etc.), it is necessary to rely on the cross section of the home wiring cable and the power of consumers of electricity. It is on how much current the wires can pass through themselves and at the same time, what is the total power of all household appliances, the operating current of the switching device will depend. In this case, to select the appropriate circuit breaker characteristic, we recommend first determine cable cross-section in your house or apartment, then be guided by these tables:
- Tripping current. Simultaneously with the operating current of the machine, it is necessary to select its rating according to the operating current. As you know, when you turn on powerful electrical appliances, the starting current can be significantly higher than the rated current (up to 12 times). So that the circuit breaker does not work, perceiving the inclusion of the engine as a short circuit, you must correctly select the class of the switching device.Today, classes B, C and D can be used for domestic use. For a house and apartment, it is best to choose a class B device if the kitchen has a gas stove and there are no powerful consumers of electricity. If an electric stove or a powerful electric boiler is installed, it is better to choose a suitable class C automatic machine. Well, if you have high power motors in your private house, you need to select a switching device marked “D”.
- Selectivity. This term means shutting down in an emergency only a certain, problem area, and not all the electricity in the house. Here it is already necessary to penetrate a little into the logical chain and select the ratings of the circuit breakers according to the service line. The top of the so-called branching should be occupied by an input automatic machine, the rating of which should not exceed the maximum allowable load on the wiring, based on the cross section of the wire. The rated current of the input switching device must exceed the value of the operating current of all the other downstream circuit breakers in the panel. For a private house, it is recommended to choose a device for 40A for input, 32A for an electric stove, 25A for electrical appliances up to 5 kW, 16A for sockets and 10A for lighting. When choosing this optionswitchboard assembly the condition of selectivity will be satisfied.
- Number of poles. Another, no less important selection criterion, with which, as a rule, the least questions arise. So, for a single-phase 220 Volt network, it is recommended to choose a bipolar single-phase circuit breaker for input. For lighting and separately connected household appliances (for example, a washing machine, water heater, air conditioning), you need to choose a suitable single-pole circuit breaker. If you have a three-phase power supply in your house, buy a four-pole switching device for input. Well, to protect the motor from overcurrents, you need to choose a three-pole circuit breaker for 380 volts.
- Factory manufacturer. It is very important to choose the right company of the machine, otherwise when buying a fake it is far from the fact that the above parameters are in fact the same. As a result, with a short-circuit current, the electromagnetic release may not work and, as a result, a fire in the house. To prevent this from happening, it is recommended to select switching devices and other automation only from high-quality companies. Rating of the best manufacturers of circuit breakers we provided in the corresponding article!
We also recommend that you watch the video instruction, which provides all the necessary tables and formulas for choosing a circuit breaker for current, power and cable cross-section:
The listed criteria for choosing a circuit breaker are basic, and first of all pay attention to these parameters. It should be noted that saving on machines is very stupid! The difference between a high-quality product (from the manufacturer ABB or Schneider Electric) and a fake is not too big, considering that your house is at stake and, more importantly, life!
Invalid purchase errors
There are several mistakes that electrical novices can make when choosing a circuit breaker in terms of current and load. If you choose the protective automatics incorrectly, even having missed a bit with the nominal, this can lead to many adverse consequences: the machine tripping when the appliance is turned on, the electrical wiring will not withstand current loads, the service life of the circuit breaker will quickly decrease, etc.
To prevent this from happening, we recommend that you familiarize yourself with the following errors, which will allow you to choose the correct circuit breaker for your house or apartment in the future:
- The first and most important thing you should know is that during the conclusion of the contract, new subscribers order the energy capacity of their connection. From this, the technical department calculates and selects in which place the connection will take place and whether the equipment, lines, and TP can withstand the load. Also, according to the declared power, the cable cross-section and the rating of the circuit breaker are calculated. It is unacceptable for apartment subscribers to arbitrarily increase the load on the input without upgrading it, since the project has already declared power and laid the power cable. In general, the value of the introductory machine is not chosen by you, but by the technical department. If in the end you want to choose a more powerful circuit breaker, everything should be coordinated.
- Always focus not on the power of household appliances, but on the wiring. You should not choose a machine only according to the characteristics of electrical appliances, if the wiring is old. The danger is that if, for example, you choose a 32A model to protect the electric stove, and the cross section of an old aluminum cable can only withstand a current of 10A, then your wiring will not withstand and will quickly melt, which will cause a short circuit in the network. If you need to choose a powerful switching device for protection, first of all replace the wiring in the apartment to a new, more powerful one.
- If, for example, when calculating the appropriate rating of the machine according to the operating current, you have an average value between two characteristics - 13.9A (not 10 and not 16A), give preference to a larger value only if you know that the wiring will withstand the current load at 16A.
- For a summer residence and a garage, it is better to choose a circuit breaker more powerful, because a welding machine, a powerful submersible pump, an induction motor, etc. can be used here. It is better to provide for the connection of powerful consumers in advance, so that you do not overpay on the purchase of a larger switching device. As a rule, 40A is enough to protect the line in domestic conditions of use.
- It is advisable to pick up all the automation from one, high-quality manufacturer. In this case, the probability of any non-compliance is minimized.
- Buy goods only in specialized stores, and even better - from an authorized distributor. In this case, you are unlikely to choose a fake, and besides, the cost of products from a direct supplier is usually slightly lower than from intermediaries.
That's the whole technique of choosing the right machine for your own house, apartment and cottage! We hope that now you know how to choose a circuit breaker in terms of current, load and other, equally important characteristics, as well as what mistakes should not be made when buying!