- Administrative and legal issues
- Overhead connection
- Driveway connection
- Counter location options
- Selection and laying of the lead-in cable
- Connecting the cable to the meter and the ASU
When organizing the power supply of a house or apartment, it is very important to correctly calculate and mount the input. The durability of the entire electrical network and the safety of its operation depend on compliance with the requirements of the PUE at this stage, therefore, in the article we will give the basic installation rules and connection options.
Administrative and legal issues
To connect to the electrical network, the home owner needs to obtain permission from the power supply organization, which often entails a lot of bureaucratic delays. The basis for issuing a permit is an internal power supply project (IPP), which contains a complete description of the home electrical network with a careful recalculation of the number of pantographs, their power and operating mode. Based on this, the amount of allocated power and the consumption limit for future connection are determined.
In accordance with the PVE, technical specifications (TU) will be determined, which regulate the connection method, engineering aspects and requirements that must be fulfilled by the customer. For example, if the distance from the building to the nearest support of an overhead power transmission line exceeds 25 m, it will be necessary to install another concrete pole or pipe support.
Connection works can be performed by a RES team or a third-party contractor with an appropriate license. When building a turnkey house, the main contractor often has appropriate approvals, however, the involvement of third parties will require an acceptance procedure and drawing up an act of work performed. On the other hand, assigning work to the installers of the distribution zone is an additional estimate, and it is not at all a fact that the price of installation work will be less.
Most often, a self-supporting insulated wire (SIP) with a service life of about 30 years is used to connect from overhead power lines. The main problem is that the self-supporting insulated wire is used only for street laying. Despite its high wear resistance, this wire has difficulties with heat dissipation, for this reason it is forbidden to mount it in walls and attic spaces, as well as to tighten it into a corrugated pipe. On the outer wall, the self-supporting insulated wire is laid along special front fasteners, which standardize the mandatory clearance of 6 cm.
1 – SIP wires; 2 – fastening the self-supporting insulated wire to the house; 3 – cable entry into the house through a sleeve
Instead of a self-supporting insulated wire, it is allowed to use a cable suspended on a cable in a protective sheath, or having a braided steel core. The cable is pulled between the support and the ridge of the roof; at the point where the conductor passes to the wall, slack is necessarily left. Like self-supporting insulated wire, a cable on a cable can be unacceptable from an aesthetic point of view, therefore, to preserve the appearance of the facade, an underground cable entry is used..
Laying the cable in the ground is a more laborious and costly way of organizing the input. It will take at least 14 meters more cable, plus it is imperative to use a polyethylene pipe as a protective sheath. Carrying out land works in some cases may require agreement on the presence of underground utilities, and this is an additional waste of time and money.
An alternative option is to lay an overhead line to the pipe stand, on which the metering unit is fixed, and lay the internal power supply cable in any convenient way. In this case, there are no specific requirements for the location of the meter, the main thing is that the inspector has free access, and the metering unit is located in a protected area.
1 – pipe stand; 2 – metering board; 3 – underground wire laying
Residents of apartments, by contrast, are easier to organize the input of electricity. It is enough to lay the cable along the wall, protecting it with a plastic box or corrugated sheath. If there is access to the floor panel, it is better to immediately bring the cable inside by drilling a hole opposite the free technical well. The cable must be long enough to connect to the meter terminal row, but leave a loop 50–70 cm long.
The energy supplying organization does not have to be informed about the carrying out of these works, but the issue of dust, noise and the laying of communications along the walls of the entrance should be agreed with representatives of housing and communal services and the house cooperative. RES has a special procedure for switching consumers to a new input. The electrician will perform all the work within a few hours, and the energy sales inspector will accept the metering unit and seal it. You just have to make the switch on the introductory panel in your apartment.
Counter location options
The main difficulties for electricity consumers arise when placing a metering unit inside a house or apartment. In this case, the passage of the cable through each wall and its wiring in the grooves should be documented in the act of hidden work, so it is unlikely that it will be possible to carry out the electrical installation on your own..
If the meter is installed on the facade of the house, the self-supporting insulated wire is brought directly into the accounting box. If it is required to conduct an input into the building, by means of piercing clamps they pass from the wire to the cable. Typically, representatives of energy sales are extremely negative about any breaks in the line to the meter, so both clamps should be placed inside a waterproof box, in the lid of which there are holes for installing seals. The inspector will be satisfied with this option, and he will not insist on the installation of wiring that violates fire safety rules.
The cable passage through the external wall is carried out using a steel or polyethylene casing sleeve. In wooden houses, the cable must be laid inside a solid steel sheath up to the input distribution device (ASU). The end of the shell or pipe, brought out into the street, is tilted straight down to protect it from falling inside drops of oblique rain.
Selection and laying of the lead-in cable
The quality of cable products determines the service life of the bushing. It is allowed to use exclusively copper cables VVGng or VVGngd. A two-core cable is used to connect to a single-phase network, and a four-core cable is used for a three-phase network. The neutral core of the latter may have a smaller cross-section (marking + 1x). When connecting from the driveway, an additional conductor is required for the protective conductor.
The cross-section of the cable cores depends on the load, but it is not recommended to use cables with cores less than 2.5 mm2. If the rated load current exceeds 27 A, the conductor cross-section must be at least 4 mm2, and with a current value over 34 A – at least 6 mm2. The cross-section of the protective conductor must not be less than 4 mm2.
Connecting the cable to the meter and the ASU
An automatic or differential automatic device installed at the beginning of the electrical circuit of the main board can serve as an input-distribution device. On its clamps there is a point of maximum electrical power of the entire network, so the conductors need to be stripped 15–20 mm and rolled into a loop for more reliable contact.
If the connection to the meter is made independently, the cable cores are stripped by 25–30 mm and inserted into the holes of the terminal row, tightening with two screws. In a single-phase meter, the phase wire is connected to terminal No. 2, zero – to terminal No. 4. In a three-phase meter, the line voltage is removed at terminals No. 2, 4 and 6, the zero conductor is connected to one of the two extreme right terminals. Connection work is performed before the input is connected to the power transmission line.