The self-made creation of an electric wiring of an apartment or a house is a painful process, participation in which most avoids. The frightening requirements for knowledge of the PUE and no less serious electrical circuits do not at all mean your helplessness. Risk of making a correct selection of the wire cross-section by summary table values is not so terrible. Do you want to learn how to do this?
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We design electric wiring
Incorrectly selected wire cross-section, which does not correspond to current loads, will cause overheating of the wire and melting of the insulation of the wiring.
In the case of professional design and electrical wiring calculations, a layout plan is initially made. It is necessary to take into account the main points of design of the scheme:
• Mandatory grounding of the wiring and application of protection (RCD or differential)
• power of consumers of electricity in a dwelling
• Wire laying conditions
• meter connection
• Selection of the type of conductor material and cross-section of the cable cores.
After designing the electrical wiring and drawing up the scheme, we determine the total power of electricity consumers.
Calculation of the total power of consumers of household appliances
The paramount parameters affecting the calculation of the current flowing through the wire are the power consumption of household appliances and the electricity supply of the apartment. Regulatory document in this case are the Rules of the Device of Electrical Installations (PUE). Select the permissible current values for the cable according to the table and select the appropriate cable value.
basic method for calculating the cross-section of a wire
There is a basic technique for selecting the wire cross-section, based on the main rules:
• The cross-sectional area of the conductor must be sufficient to allow the current to flow unhindered.
• the cross-sectional area must satisfy the maximum permissible voltage level
• The thickness of the wire and the quality of the insulation must provide mechanical strength.
In real life, no one will be engaged in modeling the flow of current through the wire cross-section. Therefore, determine the power of consumers of connected devices and the voltage of the network to find the current strength.
how to calculate the power consumption and current
In the average apartment there are heating appliances with different power consumption. For example, such devices:
The total power is determined simply by summing all the consumer elements. Consider the calculation of the cross-section of wires in the example of a 2-room apartment.
Conditionally the load of consumption is divided into groups: power and lighting. The main power group in the apartment is the outlet group.
calculation of the socket group
The projected wiring is divided into several groups:
• Sockets of apartment rooms
• Bathroom sockets
• kitchen and corridor outlets
• Illumination of the whole apartment.
For the outlets of the bathroom and kitchen, the main consumers with a daily peak load are: a refrigerator, an electric kettle, a microwave oven, water heaters and a washing machine.
Having calculated the total power of consumers, we determine the current by the known formula:
Having determined the magnitude of the current strength, the current section of the wire is selected from the table. The table was compiled on the basis of the normative document GOST 31966-2012 "Power Cables with Plastic Insulation". If the calculated and tabulated values are different, the nearest value is selected from the table.
The summary table for selecting the wire cross-section is composed for "... current loads of cables with copper and aluminum conductors".
For the rosette group according to the table, we select a wire with a cross section of 2.5 mm2.
Then the power load is distributed among the rooms, the kitchen and the bathroom. It turns out for 3 sockets for kitchen and bathroom section 2.5 mm2. For living rooms it will be enough to use 2 sockets.
calculation of lighting throughout the apartment
Based on the calculated value of the current strength and the tabular value, we select the wire cross section for illumination. Based on the existing regulatory values, the permissible load should not exceed 4.6 kW. To supply lighting, a 1.5-2.5 mm2 wire is required.
Recommendations for choosing the cross section for power
It should be remembered that the power in the sections of the electrical wiring of the apartment is different. The maximum power value will be at the entry area of the wiring to the apartment. Thus, the selection of the wire cross section for power at the supply wire is selected from 4 to 6 mm2.
Specialists, when calculating the cross section, suggest buying cables in PVC insulation with copper conductors.
This is ideal for hidden wiring in the apartment.
Specialists also recommend choosing the cross-section of the electrical cable of the apartment with a current reserve, excluding the occurrence of heating. The choice of the cable brand determines the operating conditions.
Demanded for residential premises are cables with single-wire veins, BBGng and VVG marks, as well as stranded multi-stranded PBBP and PVS.
How to make your own selection of the wire section, tell the video.
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