When planning to install modern built-in appliances in the kitchen, many apartment and home owners are faced with a technical issue that is often overlooked before buying. It is about the right selection of protective automation. Electric oven cabinet It is a powerful energy consumer, and its incorrect connection can lead to overloading of wiring, permanent power outages or even a fire situation.
The choice of the right automatic switch depends on many factors: the power consumption of the device, the cross section of the laid cable and the state of all electrical wiring in the room. You can not make a mistake here, since the machine must not only withstand the workload, but also instantly respond to a short circuit. In this article, we will discuss in detail how to calculate the required denomination and avoid common errors during installation.
Determination of oven power consumption
The first step before going to the store for an automatic switch is to accurately determine the power consumption of your future or existing device. Modern. wind-cloth They can have different power, which directly affects the current strength in the circuit. Usually this information is indicated on the factory sticker located on the end of the door, on the back wall of the case or in the technical passport of the product.
Most standard embedded models consume 2.5 to 4 kW. However, there are more powerful professional options, as well as models with steam function that require even more energy. Current power The power (W) is divided by the voltage in the network (220V). For example, for an oven with a power of 3 kW, the current will be approximately 13.6 Amps. It is from this figure that further calculations will be made.
It is important to note that manufacturers sometimes specify the maximum power that is achieved when all heating elements are simultaneously operated. In reality, the oven rarely runs at the limit of possibilities all the time, but the machine should be designed specifically for peak values to avoid false positives when warming up or working the grill.
⚠️ Warning: Never focus on the “average” values. If the instruction indicates a power of 3.5 kW, the calculation is for 3.5 kW, and not for 3 kW, otherwise the machine will constantly knock when the convection mode is turned on.
If you plan to connect the cooker panel and the oven in one chain, which is categorically not recommended for powerful models, the total power will be much higher. In this case, the calculation is carried out for the sum of the currents of both devices, which often requires laying a separate line from the shield.
Calculation of the nominal value of the automatic switch
After you have learned the current consumed by the device, you need to choose the appropriate denomination of the machine. The standard range of circuit breakers includes values: 6A, 10A, 13A, 16A, 20A, 25A, 32A and so on. For most household ovens consuming up to 3.5 kW, the best choice is a machine on the floor. 16 Ampere.
Why 16A? If your design current is, say, 14 Amps, setting the machine to 10A will cause the lights to permanently shut down. Installing a 20A or 25A machine with weak wiring is also dangerous: the machine will not work when overloaded, and the cable will start to warm up, melting the insulation. Automatic switch It protects the cable first, and then the equipment.
There is also the concept of time-current characteristic denoted by the Latin letters B, C or D. For household appliances, including ovens, most often used machines with characteristics "C". They withstand short-term starting currents that can occur at the time of switching on the heating elements, but quickly turn off when sustained overload.
The Golden Rule: The denomination of the machine is selected by the cable cross section, not just by the power of the device. The machine should not allow the cable to warm more than it can withstand.
The table below shows the dependence of the nominal value of the machine on the cross section of the copper cable and the approximate load power for the single-phase network 220V:
| Cable cross-section (mm2) | Score of the machine (A) | Max. power (kW) | Recommended type |
|---|---|---|---|
| 1.5 | 10 | 2.2 | Lighting, low-power equipment |
| 2.5 | 16 | 3.5 | Rosettes, oven cabinets |
| 4.0 | 25 | 5.5 | Powerful stoves, saunas |
| 6.0 | 32 | 7.0 | Entrance to the apartment, electric boilers |
Requirements for electrical wiring and cable cross-section
Safety of operation electric oven It depends on the quality and thickness of the wire used. According to modern standards of PUE (Rules of the Device of Electrical Installations), to connect kitchen appliances with a capacity of up to 3.5 kW, it is necessary to use a copper cable with a cross section of at least 2.5 mm2. If the power of the device exceeds 4 kW, the cross section should be increased to 4 mm2.
The use of aluminum wires in modern conditions is considered a moveton and a potentially dangerous solution, since aluminum has the property of "flowing" in the places of contact and oxidizing, which increases the risk of fire. If your house is old aluminum wiring, before installing a powerful oven, it is strongly recommended to replace the section of the line to the switchboard or shield with a copper cable. VWGng-LS or NYM.
The cable should be three-core: phase, zero and ground. The lack of grounding in a modern apartment is a violation of safety rules. The body of the oven is metal, and when the insulation breaks down, a deadly tension can appear on it. The ground conductor provides current to the ground and protection.
When laying a new line, avoid twists. All connections must be made through terminal pads, shells or soldering. The violin weakens over time, begins to spark and warm, especially under the load of a powerful consumer.
Connection scheme and socket selection
Connection of the oven can be carried out in two main ways: through a regular euro outlet with a ground or directly through the terminal pad. The first option is suitable for devices with a capacity of up to 3.5 kW. In this case, a standard socket for 16A and a fork of the corresponding nominal value are used.
If you choose an outlet option, make sure it is of high quality and has a ceramic base that better removes heat than plastic. Cheap plastic outlets with prolonged operation of the oven at high temperatures can melt. For powerful models (from 4 kW and above), the use of sockets and plugs is not recommended - it is better to use direct connection.
Direct connection is carried out through a separate machine in the shield, the cable goes down and starts directly into the oven terminal. In this case, between the machine and the device can be installed heat-resistant cable, and for ease of service in the gap phase often put a separate switch (not automatic protection, namely the switch load) to shut off the device without climbing to the shield.
☑️ Checking before connection
⚠️ Note: When connecting directly, make sure the circuit breaker is in an accessible location or is marked. In an emergency, you should quickly know which lever is turning off the oven.
Color marking of wires should be strictly observed: yellow-green - grounding, blue - zero, white / brown / black - phase. Confusing phase and zero in a TN-C-S or TN-S system is not critical to the operation of the technique, but confusing ground with zero is deadly.
Installation of the RCD: necessity or excess?
Many people ask: do you need a separate RCD (protective shutdown device) for the oven? The answer is yes, if it is not already installed on the entrance to the apartment. CCD protects a person from electric shock in a leak, for example, if you touch the metal body of a faulty device or if water gets inside.
For kitchens where humidity is high and the risk of moisture, the installation of a 30 mA (0.03 A) leakage ultrasound is a mandatory safety standard. The automatic switch protects the wire from overheating, and the ultrasound system saves a person's life. These devices perform different functions and do not replace each other.
There are two options for implementing protection: installing a separate RCD on the oven line or using a differential automatic (difavtomat), which combines the functions of a conventional automatic machine and RCD. The diffautomatic takes up less space in the shield, but costs more. The usual bundle "Automatic + ultrasound" is more flexible and clear in diagnosis.
What is the difference between a RCD and a Difavtomat?
UZO (Protective Shutdown Device) responds only to current leakage and does not protect against short circuit or overload, therefore, requires mandatory installation in pair with the machine. A diffautomatic is a combined device that protects both from leakage and from overload / KZ, taking the place of one module.
When choosing a RCD, pay attention to the nominal current. It must be equal to or greater than the face value of the machine. For example, if the machine is 16A, the RZO must be 25A or 40A (but not less than 16A). If you put the RCD on 16A and the machine on 25A, the RCD will burn when overloaded.
Common errors in installation and operation
Even if you know the theory, it is easy to make a mistake when editing. One of the most common is the use of a weak cable "back-to-back". If the oven consumes 3.3 kW, the current will be almost 15A. The 2.5 mm2 cable holds about 21-25A under ideal conditions, but in a closed channel or beam with other wires, its current conductivity drops. As a result, the isolation will warm up for years until a breakdown occurs.
The second mistake is poor contact in the terminals. It is not enough to just insert a wire and press it slightly. Under the influence of temperature, the metal expands and contracts, the contact weakens, sparking and heating begin. After six months of operation, it is necessary to conduct an audit and tighten the terminals.
The third mistake is connecting a powerful oven and cookboard to one machine through a conventional household extension cord or tee. It's a direct route to fire. Sockets and plugs of household extension cords are rarely designed for a current of more than 10-16A in long-term mode, and the total load of two devices easily exceeds this limit.
Use shrink tubes or special NSHVI tips when connecting a multi-core cable. This will improve contact and prevent the breakage of thin veins inside the terminal.
Ignoring the smell of plastic when first turned on is another danger. The new device may smell a little "smell" when the factory lubricant burns out, but the smell of burnt insulation from the socket or shield cannot be ignored. This is a signal of overload or poor contact.
Frequently Asked Questions (FAQ)
Can I connect the oven to a regular outlet if there was a refrigerator there before?
This depends on the cross-section of the wire hidden in the wall and the denomination of the machine protecting this line. If the wiring is 2.5 mm2 copper and the automatic 16A - it is possible. If the wiring is aluminum or automatic 10A - it is impossible, the wiring will warm up or knock out the machine. You need to get in the shield and look at the markings.
Constantly knocks out the machine when turning on the oven to the maximum. What do I do?
Chances are, the machine's face value is too small for your oven model or the wiring can't withstand the load. Check the power of the device. If it is about 3-3.5 kW, and it costs 10A or 13A, it should be replaced by 16A, but only after checking that the cable has a cross section of at least 2.5 mm2.
Do I need a separate oven machine if there is a common one in the kitchen?
For powerful devices (from 2.5 kW), it is desirable to allocate in a separate group. If the oven and, for example, a microwave or kettle hang on one machine 16A, then when they are simultaneously turned on, they can create an overload. A separate line guarantees stable operation.
Which company is better to choose: IEK, EKF or ABB, Schneider?
To protect expensive equipment and ensure safety, it is better to choose brands of the first tier: ABB, Schneider Electric, Legrand. They have more accurate performance characteristics and reliable mechanics. Budget Chinese analogues can have a scattering cutoff current, which is dangerous.
Can I use a B automaton instead of a C for the oven?
Theoretically possible, but undesirable. The "B" machines are more sensitive and can be triggered by initiating currents or short-term jumps characteristic of heating elements and control electronics. Characteristics "C" more inert to short-term overloads, which is better suited for active load.