Which automatic machine to put on an air conditioner in an apartment: selection, installation and connection of a protective device

Alexey Dedyulin
Checked by a specialist: Alexey Dedyulin
Author: Sergey Kuminov
Last update: January 2020

You probably thought about what kind of machine to put on an air conditioner in an apartment, if you decided to get such an air conditioner. The circuit breaker protects the electrical wiring from overload and possible fire. Errors made during its selection and installation can lead to wiring failure or fire.

You can choose and install the automatic machine for the split system yourself. We will help you figure out how best to do this.

Why does the air conditioner have a separate machine?

Owners of household air conditioners often wonder about the need to install a separate machine for their device and lay a separate line for it from the apartment or floor switchboard. Split low-power systems are often equipped with a wire with a standard plug for connecting to a household outlet, which adds even more questions.

The first thing to do to find out if you need to install a separate circuit breaker and lines for your device, read the instruction manual. The instructions for absolutely any air conditioner have a section on connecting to the mains.

If the requirement for a separate line and a machine is clearly stated in the manual, then it must be unconditionally fulfilled. Otherwise, you may lose the warranty on the device and run into other troubles.

Excerpt from the instructions
The manufacturer of the air conditioner in his instructions specifically indicated that it is unacceptable to connect other devices to the air conditioning switch. If your requirement contains a similar requirement, then connect the split system in a separate line with a separate machine

If there is no such requirement, then you have to make a choice yourself. To do this, you need to know what advantages and disadvantages a connection on a separate line has.

Advantages of a separate line device with a gun:

  • You can use powerful air conditioners even in apartments with old, including aluminum, electrical wiring without replacing it;
  • Reducing the negative impact of the air conditioner on the operation of other devices: the air conditioner is equipped with a compressor and fans that have significant starting currents, causing voltage fluctuations in the network when it is turned on. Such fluctuations with weak wiring can harm other household appliances;
  • Exclusion of the likelihood of overload while the air conditioner and other devices connected to the same line;
  • There is no need to test existing wiring for its performance and safety;
  • The ability to turn off the air conditioner for maintenance or repair without interrupting the operation of other devices in the apartment;
  • You can not install a wall outlet for connecting the air conditioner, but insert the wire directly into the terminal block of the device, which will look more aesthetically pleasing.

The more powerful the air conditioner and, accordingly, the more current it consumes, the more your choice should be inclined towards laying a separate line and installing a separate machine for the air conditioner.

Separate AC outlet
If the air conditioner is installed after the finishing work is completed, then you can bring a separate line to it in the cable channel. If the device is equipped with a factory cord with a plug, then you need to install a socket with grounding contacts

The list of deficiencies in the construction of a separate branch includes only:

  • It is necessary to carry out electrical work on laying a line from the shield to the device, which can damage the finish of the apartment;
  • It is not always possible to install another machine in an existing switchboard, which may require replacement or refinement.

Do not install a separate machine and a separate line for climate system, and dispensing with connecting the device to an existing household outlet is possible only if there is a direct indication of this in the instructions.

In this case, the socket must have protective grounding contacts, and the electrical wiring and the circuit breaker installed in the switchboard must withstand the total load from the air conditioner and other household devices connected to this line.

In order to find out which devices are connected to the line into which it is supposed to turn on the air conditioner, you need to turn off the machines in the apartment or floor panel one by one. It’s easier to check which household appliances were left without power, that is, they do not turn on.

Connect to a regular power outlet
Before connecting the air conditioner to an existing outlet, check what material the wiring is made of and what its cross section is. If the wiring is old aluminum, it is better not to connect the air conditioner to it

Also, do not include the air conditioner in an existing outlet if it is connected to a line from which a microwave, electric kettle, washing machine or other devices with high power consumption are powered.

If you have a low-power split system, and the choice fell on connecting to an existing outlet, then be sure to audit the wiring. Make sure that the junction boxes in the branch boxes are not oxidized or loose, the bolt clamps in the socket and the machine in the shield are not loose, and the plug of the air conditioner is firmly inserted into the socket, ensuring reliable contact.

Choosing a machine for air conditioning

Connecting an air conditioner via an independent line requires the installation of a separate machine to protect it from overloads.

The choice of an automaton is reduced to the selection of such a device that will simultaneously ensure the fulfillment of several basic conditions:

  • It will calmly pass electric current through itself from the air conditioner in normal mode (rated current);
  • Withstand a short-term increase in current split system 3-5 times from the nominal value at the time of starting the device;
  • As soon as possible, the air conditioner line will be de-energized in case of malfunctions in the device, leading to a short circuit, as well as a long excess of currents over the rated values.

It’s important to remember that even correctly matched machine able to ensure safety only if the parameters of the supply voltage meet the established requirements.

Voltage regulator
When installing a circuit breaker for an air conditioner, remember that it protects against overloads only the electrical wiring, but not the split system itself. If the voltage in your house is not high quality, then only the installation of a stabilizer will help protect the equipment

For installation in residential buildings and apartments, compact modular switches are most widely used. They are small in size, easy to install and reliable.

Also, modular machines have a wide range of rated currents, which allows you to choose the device that is most suitable for a particular air conditioner. For use in apartments, circuit breakers with rated currents from 10 to 40 A are most often used.

The choice of manufacturers of protective devices is also quite large. Two segments can be distinguished here:

  • Budget, which includes products of IEK, EKF, TDM and others;
  • Dear. It includes: ABB, SIEMENS, Legrand and SchneiderElectric.

Despite the difference in cost between cheap and expensive machines from 2.5 to 5 times, it is better to opt for devices from more famous manufacturers, as they will provide greater reliability. Even in this case, the cost of the machine does not exceed 3% of the total cost of the split system.

Characteristics of circuit breakers

In the case of a modular circuit breaker there are two types of protection, one of which is thermal, and the second electromagnetic.

Circuit Breaker Components
A small external device hides several types of protections inside, a device for extinguishing an arc during a short circuit and clamps for connecting wires

An electromagnetic release is a coil that instantly draws in an armature, opening contact, in case of a large current flowing through the circuit breaker caused by a short circuit.

To work with air conditioners, you should choose switches with the characteristics of an electromagnetic release B or C. Such machines operate when currents flowing through them are equal to from 3 to 5 and from 5 to 10 rated currents, respectively.

Such a “margin” of breaking capacity is needed so that the machine does not work on the starting current of the air conditioner.

The thermal release will disconnect the line if the current values ​​exceeded the rating 1.14 times or more. The higher this value, the faster the protection will work. If the current is 1.45 times higher, the disconnection of modular automatic machines for domestic use will occur within 1 hour.

Such protection allows you to protect the line from currents that are close in value to the starting currents of the air conditioner, but significantly exceeding them in time.

All parameters of circuit breakers are observed at an ambient temperature of +25aboutWith and installing the machine separately. In case of temperature deviation and parallel installation of several machines, correction factors are applied that take into account the heating of the machine with ambient air or from neighboring switches.

Adjustment factors
The more automata are located with each other, the lower the current of their operation. It also reduces the trip current and the increase in ambient temperature. Cold air opposite will slow down the response time

Another characteristic of the machines is the number of poles, which can be from 1 to 4. This characteristic reflects how many wires can be connected to the machine at the same time for protection.

For conventional air conditioners, single-pole machines are used, while they are installed in the gap of the phase conductor. However, the manufacturer’s instructions for the split system may include instructions for installing a bipolar device.In this case, the phase and neutral conductors are connected through the machine.

Automata with different number of poles
The machine will measure the values ​​of the currents flowing in each wire, and if the set value is exceeded in at least one of them, it will turn off the power in all wires of the line

The larger the number of poles, the more space will be required in the switchboard for installing the circuit breaker and wiring.

Subtleties of selecting a current switch

Since the safe operation of electrical equipment directly depends on the correct operation of the protective device, it is better to entrust the choice of a circuit breaker to electricians with the necessary qualifications. If you still decide to do it yourself, then start by studying the manual for your air conditioner.

Manufacturers of HVAC equipment indicate how many amperes a machine should be for an air conditioner of a specific model.

Machine current table
For each model of its air conditioner, this manufacturer indicated in the instructions the necessary current of the circuit breaker. The owner of such a split system only needs to focus on these values, choosing an automaton

If the instructions for your device say that the connection must be made through a circuit breaker with a rating of 20A, then you only need to purchase the appropriate switch with characteristic B or C. However, often manufacturers do not specify specific parameters of the machines in their instructions, but only indicate the requirements for their choice .

For example, the instructions may indicate that the machine must be turned off at a current 1.5 times the maximum operating current of the split system. In this case, in the table with the characteristics of the air conditioner, it is necessary to find the maximum current value that the device consumes. Then select the machine with the closest shutdown current.

It should be borne in mind that the rated current deposited on the machine is not its trip current. The characteristic that you should focus on is the operation of the machine at a current of 1.45 from its nominal value. According to GOST, at such a current, the machine must disconnect the line no later than an hour later.

Table with the characteristics of the air conditioner
For the air conditioner indicated in the left column, the maximum current is consumed in heating mode and is 12.5 + 10 = 22.5A. The nearest IEK VA 47-29 series machines have ratings of 20 and 25A, while the currents that turn them off for an hour are 1.45 times greater and amount to 29 and 36.25A, respectively

According to the instructions of the manufacturer of the air conditioner, the circuit breaker current must be 1.5 from the maximum current of the device, that is, 22.5 × 1.5 = 33.75A. Under this condition, an automatic machine with a rating of 25A passes.

The same rule for choosing a machine should be followed if the instructions do not formulate requirements for its choice. Most often this happens if the air conditioner has a small capacity and is equipped with a plug for plugging into a regular outlet, and you decide to connect the device via a separate line.

Sometimes information about which automatic machine must be installed on a split system is not indicated in the instructions. This information is in the electrical connection diagram located on the split system unit itself or on the inside of the terminal block cover.

Additionally, you can check the current of the circuit breaker by knowing the cross-section of the wire that connects the air conditioner. Often this parameter is indicated in the manual for the split system. As a rule, in apartments for these purposes wires with a section of 1.5 are used; 2.5 and 4 mm2.

For each section of wires, the PUE collection (Electrical Installation Rules) indicates the permissible continuous currents at which the wiring will work without disturbances.

Heating Conductor Selection Chart
When choosing a circuit breaker for your air conditioner, check its current characteristics with the permissible continuous currents of the existing wiring.When choosing the type of cable, do not take into account the presence of protective earth wires in its composition, since in operating mode it does not affect heating, because no current flows through it

For two-core wires of the indicated cross-sections with a hidden installation (in a strob, in a corrugation or in a cable channel), these currents are:

  • For 1.5 mm2 - 18A;
  • For 2.5 mm2 - 25A;
  • For 4 mm2 - 32A.

For reliable protection of the line, the machine must ensure that the wires are disconnected if these values ​​are exceeded. In accordance with GOST, any machine can be turned off only when the current flowing through it exceeds 13% above the nominal. Until this value is reached, the machine will not turn off.

Thus, the following machines are suitable for protecting wires:

  • For 1.5 mm2 - 16A (16 × 1.13 = 18A ≤1 8A);
  • For 2.5 mm2 - 20A (20 × 1.13 = 22.6A ≤ 25A);
  • For 4 mm2 - 25A (25 × 1.13 = 28.3A ≤ 32A).

In practice, there are cases when the values ​​of the circuit breaker currents indicated in the manuals for the installation of split systems exceed the permissible currents for conductors determined in accordance with the PUE. In these cases, it is necessary to be guided by the requirements of the rules, and also contact the manufacturer for clarification.

Machine installation process

Despite the apparent simplicity of mounting the circuit breaker, this is a responsible procedure, the reliability of the equipment and your safety depend on the quality of execution. This is especially true of work in existing electrical installations, where there is a danger of electric shock.

In accordance with the current rules for the installation of a circuit breaker, only appropriate electrical personnel can carry out the installation.

Electrical installation rules indicate that the circuit breaker should be installed directly on the branch of the protected line from the supply line (Section 3.1.16). That is, the best place to install the machine is apartment or floor board.

Housing shield
Installation and connection of the machine in the apartment panel can be done independently. To do this, completely de-energize the shield by turning off the input circuit breaker and make sure that there is no voltage with a multimeter. Install the machine in a free place and connect it. Sign the machine to know that it is turning off

Before installing the protective switch, you need to make sure that the existing switchboard has enough space for its placement, as well as for the establishment and wiring of additional wires. The machine is mounted on a DIN rail. The power wire from the input or group machine is connected to its upper clamp, and the wire of the line to the air conditioner to the lower one.

When installing the machine, you need to connect the wires in accordance with their color designation. This is necessary for the correct operation of the device and the functions of protective grounding and disconnection.

A phase wire is connected to the machine. In most cables, it is white, less often red or brown. The zero conductor is clamped in the zero bus in the shield and has a blue designation, less often black. The third required wire is protective ground. It must be connected to the ground bus, or to the grounded shield body. The color of such a conductor is yellow-green.

During installation, it is necessary to ensure that the rating of the machine for the air conditioner is not equal to and does not exceed the value of the input or group machine in the shield. Otherwise, it is the group switch that will be the first to trip, powering off the entire apartment, including its lighting.

If it is impossible to fulfill this condition with the existing group machine, then it must be replaced by a more powerful one.

Floor shield
Since improper installation of the machine in the floor panel of an apartment building can lead to the failure of electrical equipment not only of yours, but also of neighboring apartments, for installation and connection of the machine in this case, be sure to contact your management company or partnership

In the event that it is not possible to install the air conditioning machine in the floor or apartment panels, the rules allow it to be installed at a distance from them. At the same time, the length of the wire from the shield to the machine should be no more than 6 m, and the installation of a protective device will require the installation of an additional shield or box.

Installation of the machine in a separate box
Installing the machine in a separate box does not cause difficulties. Such a box is equipped with a built-in DIN rail, and can be equipped with a zero bus. Install the box on the wall with suitable fasteners, lock the switch, connect the wires and close the cover

In the case of such an installation, the cross-section of the wire from the shield to the machine must be at least the cross-section of the wire from the machine to the air conditioner. Also, before installing a separate machine and a supply line on the air conditioner, make sure that the cross-sections of the supply line wires in the panel will withstand the additional load created by the split system.

Typical errors when installing the machine

The most common mistake when choosing and installing a machine to protect purchased split systems is an overestimation of its current characteristic. Most often this is due to the desire to hedge against a “false” response.

This approach is really justified if the machine is installed in a room with a high temperature or is subject to any kind of heat. In this case, the thermal release can operate at lower currents, and the heating factor must be taken into account when choosing a switch, using the correction factor.

In all other cases, overstating the rating of the machine is unacceptable, as it can lead to a delay in disconnecting the line and breaking it down to fire. The second mistake is to install the machine on a split system with a rated current equal to or greater than the current of the main machine in the shield. Such a mismatch threatens to completely shut off the power supply in the apartment.

A common mistake during installation is insufficient stripping, partial insertion of wires into the clamp of the machine or their weak tightening. This is especially true for wires with a small cross section. Such a violation will lead to a large heating of the junction, as a result of which the insulation of the wire and the switch will melt, which can cause a fire.

A similar error when connecting wires is getting the stripped wire into the terminal space. In this case, the wire is not tightened at all, and the contact disappears with increasing load. This process can be accompanied by sparking and burning of the wire when the air conditioner is running.

Burnout of machine terminals
When installing the machine, strip the wires to a sufficient length, make sure that the wire is inserted into the clip correctly and tighten it. After tightening, check if the wire is loose in the clamp

Sometimes there is an error with the choice of the installation location of the machine. As a result, it is installed not on the branch at the supply line, as prescribed by the rules, but in the immediate vicinity of the air conditioner. Such a installation does not protect the line from the shield to the machine from overloads at all, and the switch does not carry a protective function, and only allows you to turn on and off the air conditioner.

Conclusions and useful video on the topic

Video about laying your own line to the air conditioner and connecting it to a separate machine in the shield:

The video tells how to install additional differential machines in the floor shield:

Video about the device and features of machines:

It is better to connect the air conditioner in the apartment on a separate line with the installation of a circuit breaker. This will protect you from a number of problems in the operation of electrical equipment and make the use of an air conditioner safer.

The selection and installation of circuit breakers is a rather complicated process, on which the reliability of electrical equipment and the safety of people depend. Therefore, it is better to entrust these works to electricians and installers with appropriate education and experience.

If you decide to do everything yourself, the first thing to start with is to study the instructions for installing a split system. Often it has direct instructions for choosing a machine and wire.

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