Any person who decides to build his own house, cottage or a simple plot for maintaining a personal household is forced to tackle the issue of connecting to centralized power grids. This can be done during the construction of a specific residential facility, as well as after completion of construction. To understand the essence of the upcoming procedures, it is important to understand the tasks that are solved during the preparation of the project and the composition of the documents included in it.
Why do I need a project
The main purpose of a typical electrician project in a private house is to determine the calculated data on the load characteristics of the internal network. At the same time, individual characteristics of a newly built country house or a two-story cottage are taken into account. According to the legislation of the Russian Federation, a project to connect electricity to a private house is not required if the power consumption declared by its owner does not exceed 15 kW (taking into account the existing one).
When submitting an application to Energosbyt for a typical technological connection, it is sufficient to provide a calculation of the total power consumption and a single-line local power supply scheme. However, some regional representatives of energy supply companies indicate in the contract the need for preparing an electrical project. At the same time, it is assumed that it necessarily provides a wiring diagram with a designation of specific consumers and accurate data on the meter.
Typical project for power supply of a private house
The power supply project of a private house includes the following required documents:
- Single-line electrical circuit (including distribution board).
- The plan of the house with the designation of equipment locations, as well as the location of outlets and lighting fixtures.
- The scheme of bends outside the house, equipped with the aim of connecting external devices or external outbuildings.
- Estimated ground loop data.
- Plan for organizing a lightning protection device.
- Specification for protective and control equipment (apparatus).
- Permissive documents confirming the legality of the work performed by the design organization selected by the contractor.
The last sample of the working document is necessary if approval of the project with the energy supply organization is required.
Requirements for the project of power supply of a private house
Before preparing a project for a summer residence, for example, first of all, it will be necessary to obtain technical specifications from Energosbyt for its development. They spell out the entire list of issues related to the arrangement of electrical wiring. The following items are mandatory included:
- The layout plan for the country house.
- Type and installation location of the switchboard.
- List of equipment to be installed, including an electricity meter and circuit breakers.
- Breakdown of consumers into groups and other issues.
The technical specification also stipulates the power allocated to this object (no more than 15 kW).
It is necessary to prepare an act on balance sheet ownership, in which all attention is focused on the delineation of the areas of responsibility of the supplying organization and the private consumer. It is drawn up in the form of an agreement concluded between two interested parties and approved after approval.
The presence of this document allows you to:
- to distribute the responsibilities of each of the parties in servicing “their” section of the electric network
- have a clear idea of who is required to repair if the supply line (power cable, for example) is damaged;
- connect new facilities to existing and existing electrical networks.
If the boundary of responsibility cannot be established immediately, it is selected along the perimeter of the outer wall of the private house or the land occupied by the owner. By mutual agreement of the parties, other differentiation options are allowed.
House power scheme
In the scheme of connecting the house to a single-phase electrical network, the following mandatory points are taken into account:
- The cable or its replacement SIP wire is connected directly to the busbars of the shield via an electric meter.
- After it, each power supply group must be connected through a pre-calculated “current” linear automatic device based on the current set point.
- The working zero and protective conductor of each linear group, unlike phase conductors, should not be switched.
The zero core "breaks" like a phase only if there is an RCD in the linear branch, which can be set both on one group and on their combination. Further, the wires from the group machine are laid in the direction of the junction boxes. From them, electrical wiring is routed to end consumers (power outlets and light fixtures with switches).
When preparing an electrical project, the structure of the building must be taken into account, on which the selected method of laying wires depends.
In houses with a large number of rooms, the following is taken into account when drawing up the wiring diagram:
- when designing, it is convenient to divide consumers into separate groups: one for each room and office outbuildings;
- in the example of a private house power supply project, individual branches with an automatic machine designed to protect a washing machine or oven are taken into account;
- when preparing design data, the requirement of uniform distribution of loads among groups is observed: because of a significant number of consumers, they often load the network unequally.
Given all these recommendations, we can move on to the practical part of the project.
Electrical Network Design
Based on the considered scheme for a private house, when preparing a working draft of the electric network, it will be necessary to calculate the required number of groups, and then distribute the consumers. In addition, it is important to determine the installation methods of the line and calculate the possible load on all devices connected to it.
Choosing a mounting method
Preparatory procedures begin with the choice of the method by which the electrical wiring is supposed to be laid. For a private house made of timber, for example, the most suitable is an external laying, in which it stretches along the surface of the walls. If desired, it can be hidden in pre-prepared plastic cable channels.
Hidden laying must be resorted to in private houses built of bricks, foam blocks and similar non-combustible materials.
Calculation of the total load
At the next stage of work, it is necessary to calculate the total load attributable to all consumers connected to the network, which is very important for their subsequent breakdown into groups. To do this, you need to deal with the number of devices and the maximum power consumed by each of them. This indicator will most easily be found out from the passport, which is applied to any of the household products.
Having summed up all the indicators and obtained the total power consumed by all connected loads, it is possible to find out the maximum current in the circuit. To calculate it, one should use the ratio derived in practice, according to which a power of 1 kW at a voltage of 220 volts corresponds to a current of 4.5 amperes.
Load distribution by groups
The breakdown of consumers is carried out taking into account the fact that the total power of one group of lines of sockets and lighting devices should not exceed 16 Amps. Based on this requirement, it is necessary to distribute the existing loads on individual groups.
To connect and maintain powerful loads like an electric furnace, a group of consumers with a rating of 25 Amps will need to be installed.
Distribution into groups is made taking into account their distribution in rooms and depends on the power of a specific load. PUE recommends separating group lighting lines from power outlets, which is important for buildings with a large number of rooms.
Wiring selection
Before self-laying electrical wiring in a private house, you must carefully calculate the cross-section of its constituent conductors. The durability and fire safety of the entire power supply system depend on the correctness of this procedure.
According to clause 7.1.34 of the PUE since 2001, only copper cables and wires are allowed to be used in wooden residential buildings and other buildings.
The cross section of the conductors is supposed to be selected taking into account the load found on the calculation by all types of group lines. To avoid unnecessary calculations and simplify the selection of this indicator, usually proceed from the rated current of group ABs.
Be sure to take into account the type of wiring (indoor or outdoor), since for conductors laid in different ways, the conditions for heat dissipation will be different. In both cases, for group lighting lines, the cross section is selected no more than 1.5 mm square, and for power (socket) - at least 2.5 square meters. mm
