Construction lengths of cable and wire products

What is a conductor?

A conductor is a substance or material that perfectly conducts electric current.
As you all know, any substance consists of atoms. Atoms, in turn, consist of electrons and nuclei. (More details about the structure of the atom).

Let's look at this picture for understanding. Let's assume that the shepherd is the nucleus and the sheep around him are the electrons.

Those sheep that are next to the shepherd cannot just run away from him, since he is looking after them. Otherwise, he will be left without meat and wool by autumn. But those sheep that are at a distance from the shepherd have every chance of running away from him.

The same can be said about atoms and electrons. Electrons that are in the farthest orbit from the nucleus are less dependent than those that are located closer to the nucleus.

As a result, such electrons can “break away” from the nucleus and begin an independent journey through the substance. Such electrons are called free electrons .

The more free electrons, the better the conductivity of the substance.

Construction lengths of cable and wire products

Construction lengths of power cables

Power cables with impregnated paper insulation

Power cables with plastic insulation

Flexible general purpose power cables with rubber insulation

Construction lengths of control cables

Control cables with PVC insulation in PVC sheath as a percentage of the lot

Control cables with PVC insulation KUPV, KUPV-P, KUPV-Pm and KUPV-Pn

Control cables with PE insulation and rubber sheath KUPR, KUPR-P, KUPR-Pn, KUPR-Pm

PVC control cables

Control cables for fixed installation with PE insulation

Cables, wires and cords with PVC insulation

Wires with combined fiber-PVC insulation

Wires with PE insulation

Construction lengths of installation cables and wires

Irradiated polyethylene insulated wires

Wires with fluoroplastic insulation

Flat ribbon wires

Thermocouple and thermoelectrode wires

Construction lengths of control and signal-blocking cables

Control cables

Signal blocking cables

Construction lengths of special purpose cables

Marine cables with plastic insulation and sheath

Cables for mining and earthmoving

Marine cables with rubber insulation

Cables for oil fields

Construction lengths of cables and communication wires.

Telephone communication cables with PE insulation

Telephone communication cables with air-paper and porous-paper insulation

Wires and communication cords

Construction lengths of wires for electrical installations

Wires with rubber insulation

Wires with plastic insulation

Wires with heat-resistant insulation

Conductor resistance

Resistivity

And now we smoothly move on to another question: what is conductor resistance ? As I said above, the more free electrons in a substance, the better the substance conducts electric current. Therefore, the resistance of a conductor depends on how many free electrons such a conductor contains. Therefore, in physics there is such a concept as specific resistance of a substance .

Find out what a proton is right now.

Again. If a substance is full of free electrons, then such a substance will conduct electricity well. If there are even fewer electrons, then such a substance will poorly conduct electric current. And if there are almost no free electrons, then such a substance will not conduct current at all. Therefore, the resistivity of a substance shows the ability of that substance to resist electric current passing through it.

Resistivity is expressed in units of Ohm x m.

Conductor resistivity formula

Where

ρ is the resistivity, Ohm × m

R - conductor resistance, Ohm

S—cross-sectional area, m2

l—conductor length, m

The cross-sectional area of ​​a conductor is something like this:

conductor cross-sectional area

Conductor resistance formula

So, we now know such a physical quantity as resistivity. Now we can easily find the resistance of the conductor.

Where

ρ is the resistivity, Ohm × m

R - conductor resistance, Ohm

S—cross-sectional area, m2

l—conductor length, m

Section calculation

So, first of all, it is necessary to sum up the power of all household appliances. It's very simple, you can even do it in your head. For example, the result will be 7.5 kW. By the way, this is the average load in most city apartments. Just twenty years ago this figure did not exceed 5 kW. It's all about the increase in the number of household appliances we use. Now we move on to implementing the choice of electrical wire material. Comparing the table, we can conclude that in the case of a copper cable the cross-sectional value will be equal to 4 mm², and with aluminum – 6 mm². At the same time, copper with a cross-section of 4 mm² can withstand a load of up to 8.3 kW, aluminum up to 7.9 kW. That is, a certain safety margin has already been built in, which increases the reliability of the electrical wiring.

Attention! Regardless of the fact that the power reserve has already been determined, it is recommended to take a slightly larger cable cross-section (up to the next indicator). This is done for the future, because there is a high probability that new household appliances will appear in the house, which will increase the total load on the network.

Now, regarding the three-phase network. In many private houses, three phases are supplied, and in some city apartments they are also present. Basically, what is a three-phase network? These are three phases and zero. That is, it turns out that three single-phase networks enter the house. All calculations related to power and wire cross-section are carried out in exactly the same way as with a single-phase network. True, there is one strict requirement - the total load must be distributed evenly among the phases. The same example, where the power consumption of the house is 7.5 kW. So this indicator in each phase should be 2.5 kW.

What does this mean? Remember our example, where the cable cross-section for a single-phase network was calculated at a load of 7.5 kW. It was determined that the best option for this is copper wire with a cross-section of 4 mm². Since the total load of the network is divided into three phases, each of them requires a wire with a cross-section corresponding to a power of 2.5 kW. And this is 1.5 mm².

Conductors on printed circuit boards

As you know, all circuits consist of wires or printed tracks that connect various radio elements into a single whole. For example, in the article “The simplest sound amplifier,” I connected various radio elements using wires, and I got a circuit that amplified sound frequencies.

In order for everything to be beautiful, aesthetically pleasing and take up little space, “wiring” is created directly on the boards, which are already called “printed tracks”.

At home, all this is done using LUT technology (Laser-Ironing-Technology).

On the other side of the printed circuit board there are already radio elements

Since radio amateurs try to make their devices as small in size as possible, the installation density increases. Therefore, in some cases, radio elements and printed tracks are located on both sides of the board.

Industrial printed circuit boards are already made multilayer. They consist of layers, like a cake made of layers:

The boom in SMD technology has in turn created a need for multilayer printed circuit boards.

Superconductivity

Also in nature there is such an effect as superconductivity . Superconductivity is when some materials and their alloys have no resistance at all. That is, their resistance is very, very close to zero. But, I hasten to disappoint you, this is impossible to achieve under simple conditions, since this is achieved only at critical temperatures.

If you want to learn more about materials that are used in electronics and electrical engineering, download this book.

I recommend reading - Electric current power.

Parameters for performing calculations

Remember one point - the electrical network of the house is divided into sections (loops), in which it is necessary to carry out calculations separately. Plus calculate the cross-section of the common wire leading to the house. The thing is that the number of household appliances and light sources in different rooms will differ. For example, there will be more of them in the kitchen; in the hallway there is nothing at all except lighting. In addition, the modern approach to electrical wiring requires dividing areas in rooms into two groups: lighting and sockets. That is, each group will have its own separate wire.

Let's look at how to correctly calculate the cable cross-section for power in one room where several household appliances are used. So, input data.

• Maximum total load of all consumers. As mentioned above, these indicators can be found in the product passport or on the tags of the device itself. If neither one nor the other is left, then the only way for you is the Internet. Today there are many sites on the Internet that offer tables with the power parameters of each household appliance. So this is not a problem today.
• Mains voltage. This is either 220 volts or 380 volts.
• The material from which the electrical wire is made. In principle, the variety here is small, only two positions: copper or aluminum. We will not go into details; there is also a table of the ratio of cable cross-section and material on the Internet. The only thing we note is that with the same power consumption, you can install a copper cable with a smaller cross-section compared to aluminum.