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Work on connecting the cable from the power line pole to the inlet junction box on the house should be carried out by a specialized organization: this site is too responsible. However, you need to decide on the input method – overhead or underground – as well as the type of cable and its cross section. So you have to figure out how you can connect electricity from the pole to the house and choose your option.
Air electrical supply
The air method of power supply is attractive in that it does not require a lot of time and money. But the standards set requirements that not all houses meet:
- The cable entry into the house should be located at a height of at least 2,75 m. If the height of the house is sufficient, a switchboard with an RCD is mounted on the wall, and a cable from the pole is connected to it. If the house has a lower height, a special rack (pipe rack) is installed. It can be a curved shape called a “gander” (in the picture on the left) or straight (in the picture on the right). These two input methods differ in the method of fastening to the walls of the house (see photo).
Ways to install a rack for air entry of electricity into the house - From the pole to the entry point, the distance should not exceed 10 m. If this distance is greater, put an additional support. From it to the power line, the distance should not be more than 15 m.
- Withdrawal from power lines is done:
- up to 10 m – copper wire with a cross section of 4 mm;
- from 10 to 15 m – with a wire with copper conductors with a cross section of 6 mm.
- aluminum wires are used in any case not less than 16 mm in diameter.
Although copper wires require a smaller diameter, they cost significantly more than aluminum ones. Therefore, the input of electricity into the house from the pole is most often made of cables with aluminum conductors. There are two ways:
- Pull the torso or wire between the poles, attach a current-carrying cable to it on special clamps.
- Use self-supporting wires for which support is not needed: SIP (self-supporting insulated wire). It is connected using:
- insulators (glass, polymer, porcelain);
- special fittings.
Special fittings appeared not so long ago, but are becoming more and more popular. It has a certain margin of safety. When it is exceeded (falling trees, massive snowfall, etc.), the reinforcement is destroyed, but the cable remains intact, the power supply is not disturbed.
From the place where the input cable touches the wooden wall of the house, and to the place where the shield is installed, the cable must be laid in a steel pipe
Air input of electricity into the house has disadvantages:
- The wiring is exposed and can be damaged.
- Hanging wires limit the possibilities at the entrance of large equipment (truck cranes, aerial platforms, etc.).
Underground (trench) input of electricity
Another way to make electricity input to a wooden house is underground, through a trench.
In this case, the cable is lowered along the pole inside the steel pipe, its height must be at least 2 m from the ground level. Then, from the post to the entrance to the house, a trench is dug. Its depth:
- 0,7 meters, when laying the cable in a plastic or asbestos pipe or under the protection of a brick (concrete) slab
- 1 m – without protection.
The power cable enters the house also in a metal pipe. It can be drawn through the foundation (tape), but not under it. The second option is to raise the pipe along the wall by at least 2 meters, and at this height pass it through the wall, moreover, also in a metal pipe.
When connecting underground to a pole, it is recommended to use a power cable with copper conductors in reinforced insulation, preferably armored. With a power consumption of less than 15 kW, there are no restrictions on the cross section of copper conductors, but most often they use a VBBSHV cable with a core of 10 square millimeters.
All these works – up to connecting power to the electric meter and sealing it – should be carried out by a special organization. Independent connection is prohibited, and even threatens with fines: an agreed project and a certain level of access are required. But choose the type of connection, and then all the other work on the installation of electrical wiring in the house – you can do it yourself.
How to assemble an electrical panel, read here. It will be useful to read about the rules for connecting wires in junction boxes.
Cable entry through a wooden house wall or foundation
If a SIP or another conductor with aluminum conductors is laid from the pole to the wooden house, according to the PUE it is impossible to enter it into the house: “it is not allowed to lay cables with aluminum conductors on combustible structures.” You need to switch to copper. More often than others, the VVGng cable is used for this purpose – in non-combustible insulation.
It must be remembered that terminal boxes are used to connect these two conductors; ordinary twisting is unacceptable. Directly connected copper and aluminum enter into an active chemical reaction, quickly and strongly oxidize, which worsens the contact. As a result, even with minor loads, a spark appears at the junction, and this is a direct path to a fire. Therefore, the use of terminal boxes is mandatory. They are in a sealed case, there are open ones. For outdoor use, of course, sealed ones are better; open ones can also be installed in the house.
But that’s not all. Through a wooden wall, the power cable can only be passed through a steel pipe with a thick wall. The pipe diameter must be at least 4 times the outside diameter of the wire. The wall thickness is normalized (SP 31-110-2003) and must not be less than:
- 2,8 mm for a cable with a conductor cross section of 4 sq. mm
- 3,2 mm for cables with conductors 6-10 sq. mm.
It is desirable to have the entrance with a reverse slope so that water does not flow inside. To seal the entry and exit points, as well as to ensure electrical safety, asbestos, rubber or plastic plugs can be used. The edges of the pipe will need to be carefully processed and sanded until completely smooth so that the cable does not fray and its sheath is not damaged.
To calm down and increase reliability, the segment that will be inside the pipe can be wrapped with asbestos thread or other insulating material. It can also fill the space inside the pipe so that insects do not settle there. Another option is to fill the pipe with cement or alabaster mortar.
How to make wiring in a wooden house, read here.
When entering through the foundation, the situation is slightly different: the structure is no longer considered combustible, so plastic mortgages can be used. They are installed at the stage of manufacturing the strip foundation. In this case, the cable passage is different depending on whether the cable enters the room: wet or dry.
The spare parts necessary for organizing the safe entry of electricians into the house do not cost very much, but they significantly increase the reliability, electrical and fire safety of your home. The designs are quite simple, you can handle their device with your own hands.