Two-pole circuit breaker - what is it used for and how it differs from a single-pole

The automatic two-pole switch for the protection of the electrical network structurally includes 2 single-pole circuit breakers with a common closing lever and an internal blocking system. In this material, we will talk in detail about what a two-pole machine is, what are the features of its operation and installation, and also figure out what is the main difference between two-pole devices and single-pole protective devices.

Features of the operation of single-pole and double-pole AB

The essence of the work of each of these types, in general, can be understood from the name. Single-pole circuit breaker is designed to disconnect one line. The two-pole device differs from it in that it monitors the workflow simultaneously in two lines and compares the parameters of the electron flow, determining whether it corresponds to the value that is acceptable for the correct operation of the network. If these indicators are exceeded, the device works, turning off the power of both lines at the same time.

Some readers may have a question: is it possible to replace a two-pole machine with a pair of single-pole switches? This should not be done in any case. Indeed, in a device with two poles, its elements are connected not only by a common lever, but also by a locking mechanism.

This means that in the event of a malfunction, they will turn off at the same time, and in a pair of independent one-pole ABs, only one machine will operate. Electric current in this case will still be supplied to the faulty circuit through the switched on device, which can cause a fire in the wiring. Clearly about the attempts to unite in the following video:

The difference between these two types of circuit breaker lies in the design of the release. A two-pole circuit breaker must have a tripping element, the configuration of which makes it possible to simultaneously turn off both parts of the device, both with automatic operation and with manual action.

If the electrical circuit in the apartment is single-circuit, then there is no need to install a two-pole circuit breaker in it, since there is no need to simultaneously protect various segments of the room. But in the case when complex equipment is installed in one of the rooms, which, according to its parameters, cannot be included in one common circuit, one cannot do without a multipole.

For clarity, consider the following example. Let's say there are two lines in a home network, one of which is connected to a complex device, and it receives power through a rectifier.

If there is a violation in one of the lines, then as a result of its disconnection, the power supply to one circuit will cause a voltage surge, and therefore an increase in other parameters. If the AV of the second line does not work in a timely manner, the result will be a device failure, and possibly a cable fire. That is why such a network must be protected by a 2-pole device.

What will happen in the opposite situation, when they try to disconnect a multi-pole machine, in the video:

Possibilities and purpose of multi-pole devices

Installing a two-pole AB allows you to control:

• Two independent circuits with their simultaneous shutdown in the event of a malfunction.
• The parameters of each of the independent lines (although when problems appear in one of them, both are de-energized simultaneously).
• DC line having similar trip parameters.

Based on this, the input automatic device should be at least two-pole, since it will allow you to turn off the power in the whole house if, for any reason, the AV of the faulty network section did not work. As with any bagger, it also allows you to manually de-energize the apartment.

Consider this situation. A short circuit occurred in one of the home wiring lines, to which the AV of the problem area did not have time to react and burned out, turning from a switch into an electric current conductor. Even if the general network is protected by a residual current device, this in most cases will not solve the problem, since the RCD turns off the power in the event of a cable breakdown in order to prevent electric shock to people. Therefore, it will also fail, and an imbalance will occur in the circuit, which is protected by the input two-pole machine.

Clearly about multi-pole machines in the video:

If the voltage difference at the input and output is exceeded by more than 30% (and if there is a short circuit in one of the branches, this will happen very quickly), the automatic input will work, disconnecting both the phase and zero cables. In this case, the electrical network will be completely de-energized, and there will be no current leakage even to the grounding cable. Thus, the risk of equipment failure and line fire will be eliminated. Having eliminated the malfunction, it will be possible to manually turn on the machine again.

Cons of two-pole circuit breakers

Any device has weaknesses, and multi-pole network protection devices are no exception. Although there are few negative properties of two-terminal devices, we will list them:

• When two lines are closed simultaneously, the cable breaks down with an electric current.

• The thermal release will occasionally fail, which will cut off the mains power even when it is in normal condition.
• As a result of an accident, an AV breakdown may occur along one of the lines, due to which it will be impossible to turn on the power even after troubleshooting.
• Multi-pole devices have a higher sensitivity to mechanical damage compared to single switches.

Despite the listed disadvantages, protective devices providing control over two lines are common and very popular. They make it possible to secure the general network in the event of a malfunction in the line to which powerful household appliances are connected.

Safety measures when installing two-pole circuit breakers

Electrical safety regulations for the installation of protective devices on two poles generally do not differ from the general measures for the installation of other electrical devices. They are as follows:

• Installation should be carried out by two people, so that in the event of an electric shock to one of the masters, the second can provide the victim with assistance in a timely manner.

• To protect against electric shock, you must use dielectric mats and protective gloves.
• Before starting any work with power grids, you must obtain a special permit.

Conclusion

In this article, we talked about two-pole circuit breakers, their features and advantages, as well as a few disadvantages inherent in them. Summing up, it should be noted that multi-pole circuit breakers provide reliable protection for electrical networks with two circuits, especially when devices that differ significantly in power are connected to them.