Wires and cables through which electric the calculation done? flows are the most important part of electrical wiring. The calculation of the wire cross-section must be done in order to ensure that the selected wire meets all the requirements for reliability and safe operation of electrical wiring.
Safe operation is that if you select a cross-section self employed data does not correspond to its current loads, this will lead to excessive overheating of the wire, melting of the insulation, short circuit and fire.
Therefore, the issue of choosing the wire cross-section must be taken very seriously.
What you need to know
The main indicator by which a wire is how to buy an inexpensive and high-quality smartphone: smart tips is its long-term permissible current load. Simply put, this is the amount of current that it can pass over a long period of time.
To find the nominal current value, it is necessary to calculate the power of all connected electrical appliances in the house. Let’s consider an example of calculating the wire cross-section for a typical two-room apartment.
Table of power/current consumption of household electrical appliances
Once the power is known, the calculation the calculation done? the cross-section of the philippines numbers or cable is reduced to determining the current strength based on this power. The current strength can be found using the formula:
1) Formula for calculating current for a single-phase 220 V network:
calculation of current for single-phase network
Where P is the total power of all electrical appliances, W;
U is the network voltage, V;
KI= 0.75 is the simultaneity coefficient;
cos for household electrical appliances – for household electrical appliances.
2) Formula for calculating the current in a three-phase 380 V network:
calculation of current for a three-phase network
Knowing the current value, the wire cross-section is found in the table. If it turns out that the calculated and table current the calculation done? do not match, then in this case the nearest higher value is selected. For example, the calculated current value is 23 A, we select the nearest higher value from the table – 27 A – with a cross-section of 2.5 mm2.
Which wire is better to use?
Today, copper wires are, of course, very popular for installation of both open and hidden electrical wiring.
Copper is more efficient than aluminum:
- it is stronger, softer and does not break at the bending points compared to aluminum;
- less susceptible to corrosion and oxidation. When connecting aluminum in a distribution box, the twisting points oxidize over time, which leads to loss of contact;
- The conductivity of copper is higher than that of aluminum; with the same cross-section, copper wire can withstand a greater current load than aluminum.
The disadvantage of copper the calculation done? is their high cost. Their cost is 3-4 times higher than aluminum. Although copper wires are more expensive, they are still more common and popular in use than aluminum.
Calculation of the cross-section of copper wires and cables
Having calculated the load and decided on the material (copper), let’s look at an example of calculating the cross-section of wires for individual groups of consumers, using the example of a two-room apartment.
As is known, the entire load is divided into two groups: power and lighting.
In our case, the main power load will be the socket group installed in the kitchen and bathroom. Since the most powerful equipment is installed there (electric kettle, microwave, refrigerator, boiler, washing machine, etc.).
For this socket group, we select a wire with a cross-section of 2.5 mm2. Provided that the power load will be scattered across different sockets. What does this mean? For example, in the kitchen, to connect all household appliances, you need 3-4 sockets connected with a copper wire with a cross-section of 2.5 mm2 each.
If all the equipment is connected through a single socket, then a cross-section of 2.5 mm2 will not be enough, in this case you need to use a wire with a cross-section of 4-6 mm2. In living rooms, you can use a wire with a cross-section of 1.5 mm2 to power the sockets, but the final choice should be made after appropriate calculations.
The entire lighting load is powered by a 1.5 mm2 wire.
It is necessary to understand that the calculation done? power in different sections of the electrical wiring will be different, and accordingly the cross-section of the supply wires will also be different. Its greatest value will be at the input section of the apartment, since the entire load passes through it. The cross-section of the input supply wire is selected 4 – 6 mm2.
When installing electrical wiring, wires and cables of the PVS, VVGng, PPV, APPV brands are used.