Planning of power supply in a residential area begins long before the purchase of the first outlet. The foundation of the whole system is lead-inIt takes on the load of all electrical appliances simultaneously working in your home. An error at this stage can lead to constant knocking out of the machines or, much worse, to overheating of the wiring and fire.
The modern apartment is saturated with powerful equipment: electric stoves, air conditioners, washing machines and floor heating systems require stable and safe supply of energy. Nominal current The input machine directly depends on what capacity reserve is laid in the cross section of the lived. If you live in an old house, the issue of modernization is especially acute, as old networks often do not cope with modern realities.
In this article, we will discuss how to correctly determine the necessary thickness of conductive veins, what materials are better to use and what to pay attention to during installation. Security Your home depends on a competent engineering approach, not on a random selection of materials.
Calculation of the total power of electrical appliances
Before you go to the store for the cable, you need to make a thorough inventory of all electricity consumers. Total power It is not just the addition of watts indicated on the nameplates, but also the accounting of the simultaneity coefficient. It is unlikely that you will simultaneously include the oven, air conditioner, iron and water heater, but a margin of safety is necessary.
For a standard two-bedroom apartment with a gas stove, the base load is usually about 3-5 kW. If you have a setup, plateThe consumption instantly grows to 8-10 kW and above. Special attention should be paid to devices with heating elements and electric motors, as they create peak loads at start-up.
⚠️ Warning: Never count the cable cross section side by side with the passport power of the devices. Always lay a reserve of 20-30% for future expansion of the fleet of equipment and initiation currents.
Let’s look at a list of powerful consumers who can work at the same time:
- 🔌 Electric stove or cookboard (from 6 to 9 kW)
- ❄️ Air conditioning or split system (1.5 – 2.5 kW)
- 🚿 Flow water heater (3 – 8 kW)
- 🧺 Washing machine with drying mode (2 – 3 kW)
After the list is compiled, all the values are summed up. The resulting figure is the starting point for the selection machine-nominal And so the wire section.
Copper or aluminum: the choice of material lived
The dilemma of choosing between copper and aluminum wires is before anyone who started repairing. Copper cable It is a standard for modern internal wiring. It has better conductivity, is less warm and, critically, more plastic, allowing you to make multiple bends during installation without the risk of breaking the vein.
Aluminum is a cheaper, but also more capricious material. It is prone to oxidation in air, which worsens contact at the sites of the compounds and can lead to heating. In addition, aluminum veins have a “fluidity” effect, which is why the contacts in the sockets and shield require regular lifting. In apartments built before the 2000s, aluminum was often used.
Why can't you twist copper with aluminum?
With direct contact of copper and aluminum, a galvanic pair occurs. In the presence of moisture, electrolysis begins, which quickly destroys contact, causing sparking and fire. They can be connected only through special terminals or steel washers.
If you make a complete wiring replacement, the question is not even worth it: only copper. However, if you live in a house where the riser is made of aluminum, the introductory cable to the apartment (up to the shield) is also often made aluminum to avoid problems with the riser neighbors and the management company, although switching to copper inside the apartment through the correct terminals is permissible.
- 🥇 Copper: high conductivity, durability, ease of installation, high price.
- 🥈 Aluminum: low price, lightness, propensity for oxidation, requires special installation.
- ⚖️ Bimetal: Transition terminals for the connection of different metals.
In choosing cable VVGng-LS (copper) or AVVG (aluminum) be guided not only by price, but also by service life. Copper wiring will last 30-50 years without complaints, while aluminum can require attention after 15-20 years of active operation.
Table of cross-sectional and current load conformity
The main document regulating the choice of cross-section is the PUE (Rules for the device of electrical installations). It is these norms that determine what current can safely pass through a conductor of a certain thickness. Below is a table for copper cables laid open or in boxes (the most common case for input).
| Section of the vein (mm2) | Diameter of the vein (mm) | Current for 220V (A) | Power for 220V (kW) | Current for 380V (A) |
|---|---|---|---|---|
| 1.5 | 1.38 | 19 | 4.1 | 11 |
| 2.5 | 1.78 | 27 | 5.9 | 19 |
| 4.0 | 2.26 | 38 | 8.3 | 27 |
| 6.0 | 2.76 | 50 | 10.1 | 38 |
| 10.0 | 3.57 | 70 | 15.4 | 50 |
For a standard apartment with a gas stove and a power limit of 5-7 kW, the section is most often chosen 6 mm2. This allows you to install the introductory machine at 32-40 Amps. If you have an electric stove and a dedicated power of 10-12 kW, then the minimum permissible section will be 10 mm2, and the automatic machine - 50 Amperes.
It is important to note that tabular values are given for single cable. If the beam of wires lies tightly together in the cable channel, their ability to give off heat is reduced, and it is necessary to apply the down-rate. In such cases, it makes sense to take the cable a step thicker.
Always buy a cable with a margin of length. It is better to cut off the excess in the shield than to build up the wire, creating unnecessary connection points, which are the weak point of any power grid.
Single-phase or three-phase network
The type of network determines not only the number of phase wires, but also the pattern of load distribution. In most apartment buildings, it is used single-phase 220B. In this case, the apartment includes two wires (phase and zero) or three (if there is grounding). All consumers are distributed in one phase, which requires careful balancing of groups.
In new residential complexes and houses with electric stoves are often summed up three-phase 380B. This allows you to distribute powerful appliances (stove, boiler, air conditioners) in three different phases. As a result, the load on each phase is reduced, and you can use a smaller cable with the same total power.
⚠️ Attention: Switching to a three-phase network requires permission from the power supply organization and replacing the input machine. Unauthorized alteration is prohibited and dangerous.
With three-phase input, a four- or five-core cable is used. The cross section of each phase vein is calculated based on 1/3 of the total power. For example, with a total power of 15 kW, each phase will have 5 kW, which allows you to use a thinner wire than in the single-phase version.
- ⚡ Single-phase: easier wiring, cheaper equipment, the risk of phase distortion is absent (no phase).
- ⚡ Three-phase: the ability to connect powerful devices, uniform load, more complex and more expensive shields.
- ⚡ Grounding: In modern homes, it is mandatory to have a PE conductor regardless of the number of phases.
You can determine the type of network by looking at the number of wires entering the floor panel, or contacting the management company. Incorrect connection of the three-phase device in a single-phase network will lead to its failure.
Effect of the length of the track on the voltage drop
In apartments, this parameter is often neglected, and rightly so, since the distances here are small. However, if the introductory cable comes from a common shield in the basement or from a pole in a private house, the length of the track becomes a critical factor. It's showing up in long stretches. stress-down.
According to the rules, the voltage loss should not exceed 5%. If the voltage at the entrance to the apartment is too low, household appliances (especially refrigerators and pumps) may not work properly or burn. The calculation formula takes into account the length, cross section and material of the conductor.
☑️ Introductory line check
For long lines (more than 30-40 meters), it is often necessary to increase the cable cross-section by one or even two steps above the calculated one. This compensates for the resistance of the veins and provides a stable 220V on the sockets. In an apartment, where the length from floor shield to apartment rarely exceeds 10-15 meters, this can be neglected.
The temperature of the environment should also be taken into account. If the cable is laid in a hot pipe or near the heating, its throughput is reduced. In such extreme conditions heat-resistant Or an increase in the section is the only right decision.
For a standard apartment, the length of the track does not affect the choice of section, but for a private house or cottage, the calculation of the voltage drop is mandatory.
PSA standards and safety requirements
All work must be done in accordance with PUE (Rules of electrical installations). It is the electrician’s bible, and ignoring it can cost you your life. According to the rules, hidden wiring in residential premises should be performed by cables with copper veins.
Special attention is paid to mechanical protection. In the straps under the plaster cable can be laid without additional protection, but in the voids of the floors or under the suspended ceiling it must be hidden in corrugated or metal pipes. This will prevent damage to the insulation by rodents or when drilling.
Color markings should be strictly observed: yellow-green - grounding (PE), blue - zero (N), any other (usually white, brown, red) - phase (L). Confusion of colors can lead to short circuit or the appearance of voltage on the appliance body.
Can you use a cable with a smaller cross section, if you put a powerful machine?
Absolutely not. The machine protects the cable, not the device. If the cable cross section is designed for 25A, and the machine costs 40A, then at current 35A, the cable will begin to warm and melt, and the machine will not even work, which will lead to a fire.
Do I need to change the introductory cable when replacing the meter?
Not necessarily, but desirable. Older cables may have lost their properties. If you see that the insulation has become rigid and brittle, or it is black (a sign of aging PVC), the cable should be changed.
Which section to choose for giving?
For giving the calculation is similar to the apartment, but you need to take into account the length of the line from the pole. Often for country houses enough 4 mm2 or 6 mm2 copper, if there is no electric heating and powerful machines.
What to do if the machine is constantly knocking?
It's an overload signal. Either you have turned on too many appliances at once, or the cable section/nominal of the machine is wrong. You can’t just change the machine to a more powerful one without replacing the wiring.
A competent choice of introductory cable is an investment in peace of mind. Do not skimp on the cross-section and quality of insulation, because replacing hidden wiring in a few years will cost many times more than doing everything right the first time. Use quality materials, follow the rules and enjoy the safe use of electricity.