Choose cable for wiring

What cable to choose for wiring in the apartment?

It is this question that many of our fellow citizens have when they decide to replace the old one or install a new electrical network in a house or apartment. The question is quite serious and does not have a definite answer.

It all depends on the parameters of your electrical network and method of installation. And if you want to understand this question, our instruction is for you.

Preliminary parameters of our electrical network

In order to decide which cable to use for wiring in the apartment, we first need to decide on a number of parameters. First of all, you should choose the method of installation of wiring, you should also determine the number of cable cores, the parameters of the rooms where the installation is to be carried out, the number of wires laid together, and some other aspects.

Wiring method

At the moment there are two main types of wiring. This is a hidden and open installation.

Each of them has its own advantages and disadvantages, and one of them can be preferred only after detailed consideration. In addition to your preferences in the choice of not a small role played by the rules of the EMP in terms of electrical and fire safety.

Choosing a wiring method

• Open wiring is quite easy to install, has good maintainability and relatively quickly mounted. At the same time, it spoils the design of rooms, takes away free space from us and requires additional ducts or pipes for mechanical protection.
• Although, on the other hand, according to clauses 2.1.2 and 2.1.3, the requirements for open wiring during installation for combustible structures are not so strict in many respects. Due to this, for mounting on wooden and other combustible structures, this type of installation is chosen.
• Wiring the electrical cable in the apartment in a hidden way allows you to hide all engineering networks and does not require additional protection during installation on fireproof structures. At the same time, the complexity of the work is much higher, maintainability is not high, and the connection of additional electrical appliances can cause certain difficulties.
• In addition, according to the table. 2.1.2 and 2.1.3 PUE, the choice of hidden wiring for power supply of a wooden house fraught with many difficulties and the need for additional remedies. Because of this, the final price of such a transaction will be significantly higher. At the same time, clause 12.22. VSN59-88 recommends using only hidden wiring in bathrooms, bathrooms and other rooms with high humidity.
• Because of all this often, you have to choose open wiring for some rooms and closed for others. This is not a violation, but upon further selection - which cable is needed for wiring in the apartment, these features should be considered.

Select the number of wires lived

To determine what cable to do the wiring in an apartment or house, you need to know the number of cable wires. Everything is quite simple here, and the EMP gives an unequivocal answer.

Select the number of wires lived

So:

• According to clause 6.1.20 of ПУЭ, a separate zero protective wire should be connected to the sockets in the apartment from the group shield. On this basis, for a single-phase 220V network, we must use a three-core wire.
• If you are using a three-phase network, then you need a four-wire cable. At the same time, if it has branches to single-phase equipment, then it should have a protective conductor. Therefore, in this case a five-wire wire should be used.

Note! According to clause 1.3.10 of the ПУЭ, zero and protective conductors for a three-phase network are not taken into account when calculating the wire cross section. That is, if you use a four-core wire, in which one core has zero, then you make the choice of section as for a three-core wire.

The effect of indoor conditions on cable choice

An important factor to answer the question: what wire to choose for wiring in the apartment, are the conditions in the room. Temperature, humidity and dustiness also play a significant role in this. And if the dust factor for apartments does not play a special role, then it is worth paying attention to the others.

So:

• According to paragraphs 1.1.6 and 1.1.7 of the EMP, a room in which the relative humidity of the air exceeds 60% is called wet. This is typical of bathrooms and some bathrooms. Raw rooms are those in which the relative humidity of the air exceeds 75%. This is again characteristic of some bathrooms and bath rooms.
• If you have bath rooms or utility rooms where the temperature can be above 35 ° C for a long time, then this should be taken into account when choosing which wire is needed. For these purposes, Table 1.1.3 is provided in the OLC, in which correction factors for rooms with different average temperatures are given.

Table of correction factors for rooms with different temperatures

Basic parameters for selecting electrical wiring

The main parameter that allows you to determine which wire to use for wiring in the apartment is the cross section of its lived (see Perform the calculation of the wire cross section for power ). To determine this parameter, the PUE is available in Table 1.3.4 for copper wires and 1.3.5 for aluminum wires.

But, in order to use these tables, we need to know the rated current that will flow in the conductors. To do this, calculate it.

Calculation of the number of power consumers

Electric receivers include everything that consumes electrical energy in your apartment. This is a network of lighting, sockets and powerful electrical equipment, connected directly through a circuit breaker in the switchboard.

To determine the rated current of the wiring we first need to know what will be powered from it.

• According to paragraph 12.27 of the BCH 59 - 88, the apartment should have one outlet for 6A for every 6m2 room. For corridors, this rate is reduced to 1 outlet for every 10m2 room. In addition, for a kitchen area of ​​up to 8m2 there are 3 sockets for 6A, and if the kitchen area is larger, then 4 sockets. There should also be 1 socket for 10 or 16A and one socket for 25A for connecting an electric cooker (see How to install a socket for electric stove with their own hands ). If the electric stove is not provided, then the socket can not be installed.

Option placement of electrical receivers in the apartment

• It is on the basis of these norms that the number of outlets in the old-style apartments was calculated. But times are changing and the need for electricity becomes higher. Therefore, if you plan to completely change your electrical network, we advise you to revise these parameters.
• We will not give you the exact number of sockets for each room, it depends on the design, the quantities of video, audio and other household equipment and, of course, your wishes. Therefore, make your own planning, without going beyond common sense.
• As for lighting, here you are also given complete freedom of thought.
• But relatively large appliances, there are certain limitations. According to paragraph 13.15 of the BCH 59 - 88, the power of heaters installed in apartments should not exceed 2 kW. If you have installed heaters from 1.5 to 2 kW, then we advise you to power them with a separate machine from the switchboard.

Calculation of rated current wiring

Now, in order to determine which wire is needed for wiring in the apartment, we need to calculate the rated current of each individual receiver. And if everything is more or less clear with the lighting network, we calculate the total current of the lamps powered from each switch, then there may be questions with sockets.

• Any equipment can be plugged into the outlet. But each of them you planned for a specific purpose. Therefore, we proceed from the fact that the device with the highest power planned will be connected to it.
• The calculation of the rated current is carried out according to the formula I = P / U × cosα. P is the power of your appliance. If you can not find it in the passport or on the body, you can use the table below. U = 220V. Cosα - power factor, which must be specified in the passport of the appliance. If you did not find it, then boldly take equal to 1.

Table of nominal powers of various electrical appliances

Note! This calculation will help us not only to determine the cable for electrical wiring in the apartment, but also can be used in determining the nominal parameters of sockets and switches. After all, the nominal currents of these switching devices are often forgotten when buying, which leads to their rapid failure, and even fire.

Consolidation of power consumers in groups

The decisive factor in choosing the number of groups from which our apartment will be powered is clause 6.2.2 of the OLC, which does not allow the use of circuit breakers with a rating of more than 25A. Based on this, and make our division into groups.

• The division into groups can be made according to various criteria or based only on the rated currents. But, in order to avoid confusion in the future, they usually combine lighting into one or two groups, while the sockets are powered from their groups.

Note! Clause 6.2.3 of the Electrical Installation Code prohibits combining more than 20 lamps or sockets into one group. In this multi-lamp chandeliers are considered one accession.

• Also often use the division into groups by rooms. Where from each automatic machine one or two rooms eats. It all depends on your wishes and total numbers.
• If you are going to mount your own wiring, then you should remember that each group can be powered from 16 or 25A circuit breakers. Smaller denominations are not advisable, but larger ones are prohibited.

Selection of wire section

At the last stage, we can proceed directly to the selection. As we have noted above, this is done in accordance with tables 1.3.3 and 1.3.4 of OLC, which are shown in the photo in our article below.

Aluminum Wire Selection Table

So:

• To choose which wire for wiring in the apartment will be optimal, find the total values ​​of the rated currents approximately equal to your values. In this case, the number of wires should be taken into account. Choose the value closest to yours and see which wire is right for you.
• If you are going to use copper wire, then usually its cross section is not higher than 2.5 mm2. For aluminum wires, this value can be up to 4 mm2.
• We must not forget that Table 7.1.1. OLC also provides for the minimum allowable values ​​of the wire. So, for supplying individual groups, the cross-section of copper wire must be at least 1 mm2, for aluminum, at least 2.5 mm2.
• There is one more parameter that we did not stipulate earlier because we did not know the number of groups. Now, knowing how many wires we will have to run in one pipe or box, we need to take this into account. For this, clause 1.3.10 of OLC contains correction factors. Therefore, if you have more than five wires in a bundle, then the current values ​​in table 1.3.3 and 1.3.4 will be less than 0.68, if there are more than 7 wires, then by 0.63, if they are more than 10, then the value will be less by 0.6.

Copper Wire Selection Table

• But to the question: which wire is better for wiring in the apartment, the answer is quite straightforward - copper. It is not so susceptible to corrosion, with temperature overheating, it does not lose so much its properties and has a higher electrical conductivity.

Conclusion

Now you know all aspects of choosing a wire for an apartment or house. Therefore, should easily calculate and select the wiring.

Well, its installation is not a tricky business, and the articles on our website should help you cope with the most difficult issues of connecting and laying wires.