Electrification of a wooden house
The wooden house pleases its inhabitants with ease and inexpressible comfort. But wood with all its merits - a combustible material that requires a lot of attention from the standpoint of fire safety. But since the need to equip the house with electricity is not discussed today, before proceeding to work, you need to carefully read the rules for the installation of electrical equipment (PUE) and regulations GOST. In observance of these rules there are no special difficulties, but it is necessary to know about them.
- 1The basic requirements for wiring in a wooden house
2Preparation of the electricity supply project
2.1Cable cross-section calculation
- 2.1.1Table: Selecting the cable cross-section as a function of the amperage
- 2.2Calculation of wiring devices
- 2.3Selection of input cable and circuit breaker at input
- 2.4Three-phase power of a private house
3Installation of electrical wiring by own hands in a wooden house
3.1Installation of the switchboard
- 3.1.1Video: overview of the switchboard for a private house
3.2Cable entry inside the room
- 3.2.1Video: cable entry into the house and connection to the shield
- 3.3Installation of switches and sockets
- 3.4Wire connection
3.5Grounding and installation of RCDs
- 3.5.1Video: connection of circuit breaker and RCD
3.6Ways of open posting posting
- 3.6.1Video: outdoor wiring in a cable channel in a wooden house
3.7Concealed wiring in a wooden house
- 3.7.1Video: concealed wiring in a wooden door
- 4Wiring test
The basic requirements for wiring in a wooden house
The codes of the rules of the PUE and SNIP are developed by specialists in the field of security. This is not a whim of a cabinet official, but a list of necessary norms, observance of which maximizes the level of "carelessness" to the desired. It can be said that life itself writes these dry chapters, behind which sometimes human tragedies are hidden.
Statistics on fires, unfortunately, leave no doubt that wooden construction is always on the front line of the risk of ignition. However, if we remember that hundreds (and perhaps thousands) of years our ancestors lived in wooden log cabins, there is a hope that everything is possible, it is only necessary to properly understand the wiring. After all, it is in the overwhelming majority of cases that it causes a fire.
The main requirements contained in the PUE and GOSTs are as follows:
- Calculation of the wiring should be done with a margin of up to 30%. This applies in the first place to the selection of the cross-sectional area of the wires, since it determines the degree of heating of the insulation and the probability of a short circuit during operation. To cover the whole picture of electrification as a whole, it is necessary to prepare a working draft with a detailed scheme and the specification of the wiring, and upon completion of the work to obtain certification and obtain a passport wiring.
- The quality of the connections should not allow the slightest possibility of hitting the inhabitants of the house with electric current.
- Heating and ignition of cables is unacceptable, as this is likely to lead to the burning of the entire house. The possibility of short circuits should be completely ruled out.
The PUE welcomes the installation of lighting in wooden houses using 12 volt lamps and LED equipment, which is considered the safest to date. For example, in mines and mines, especially in those where methane gas accumulations are observed, and an explosion can arise from a single spark, all equipment is powered by a current of 12 volts. The same is done in cars..
A significant obstacle that hampers the independent work on the installation of wiring in a wooden house is the lack of a single document regulating the installation. The main regulations are dispersed in normative documents of GOST and SNiP and are not systematized. Therefore, when drafting a project, it is better to contact a specialized organization that has a license for this kind of activity.
Preparation of the electricity supply project
Project documentation should include all details of future posting. It shows the location of lighting devices, sockets, mounting boxes, switchboard. The specification details the brand of conductors used for wiring, their total number and nominal characteristics. All electrical appliances involved in the power supply scheme, such as an electric meter, RAM, Automated automatic machines and others, are pre-calculated for compliance with the loads expected in the process operation.
The existence of a project is a sign of a civilized and responsible approach to business.
It is possible, of course, to separate the cables without it, but:
- practice shows that the installation of wiring without a preliminary project, as a rule, costs 10-15% more. In this case, mistakes are possible, the correction of which is also worth the money;
- in case of fire, the insurance company will require a certified electrification plan for the house. In his absence, the damage coverage will be postponed for an indefinite period (until the circumstances are clarified). It's good if only one house burns out. In densely populated areas, a fire can be transferred to neighboring areas. The culprit will be the owner of that wooden structure, from where the fire began to spread. The only way to prove your innocence is to present a verified plan for the electrification of the premises;
- the plan significantly reduces the costs of preventive and repair work of the wiring in the process further operation, and also helps to quickly find and eliminate the source of damage power supply.
A full-fledged project consists not only of drawings, but also of a detailed description of all elements and equipment. As a rule, it includes:
- Graphic representation of all levels of living space, on which the location of cable, consumer and electrical equipment routes is reflected with the help of accepted symbols.
- Single-line electricity supply schemes.
- Detailed calculation of ground loops.
- Cross-sectional area of conductors.
- List of switching devices.
- Maximum current and voltage of the meter.
- Calculation of the power of the electric receiving devices.
In addition, the project should provide for outdoor lighting of the site and connection of courtyard buildings - baths, garage, utility rooms.
The project documentation is developed in several stages:
- Formulation of the problem. Electricity supply is planned in accordance with the terms of reference. The customer sets his vision to the performer verbally or through a schematic image. As one of variants, the form of the order can serve as the design project.
- Development and approval of the project. If necessary, the project is protected and coordinated with representatives of audit organizations. The parameters of electrification and the conformity of their normative documentation are specified.
- Accompaniment of the project. Sometimes it is also called supervising, during which the designer performs direct control over the performance of work.
Cable cross-section calculation
Calculation of conductors consists in determining two parameters:
- Cross-section of conductive core. The thickness of the conductor must be directly proportional to the load - the greater the power consumption of the end user, the greater the cross-sectional area of the cable should be used. Insufficient cross-section results in heating and even reflow of insulation. As a consequence, a short circuit and ignition of the wiring may occur. Therefore, save on the thickness of the cable should not be. When compiling the project, the total power consumption of each line is calculated separately and the safe cable thickness is selected. In practice, a cable with a cross-sectional area, mm2, is used to power internal lighting devices, for outlets mm2 or more. Separately selected guide for the kitchen line. If the cooker in the house is electric, then, as a rule, a cable with a cross-section of at least 6 mm2 is laid to it. The same goes for heating appliances and boilers. There are ready-made tables that will help you to choose the wire. To date, the use of aluminum wires inside living quarters is prohibited.
- Selection of insulation coating. Of all the variety of rubber and polymer coatings of wires in wooden houses, the insulation grade VVGng-LS is preferable. The letters "ng" denote "not lit and the Latin letters LS are deciphered as "smokeless" (Low Smoke). This coating creates the greatest resistance to the spread of fire in case of overheating of the cable. The NYM copper cable is also well proven, which is covered with an additional layer of insulation made of non-flammable rubber.
In the conditions of increased requirements for fire safety, the rules prescribe the mandatory use of three-wire wires. This measure is dictated by the need for protective earthing of the entire power supply system.
Table: Selecting the cable cross-section as a function of the amperage
|Cross-section of open cable||Single-phase switching, 220 V||Three-phase switching, 380 V||Cross-section of the cable laid in the pipe|
when the cable is heated to 60 oC
|power, kWt||Continuous current
when the cable is heated to 60 oC
Calculation of wiring devices
Electrical installation devices - sockets, switches and junction boxes are selected based on the technological conditions of their operation.
- Rated current and voltage. Current household sockets and switches have a voltage limit of up to 230 V and current up to 32 A.
- The posting type is hidden or external. When concealed wiring in a wooden house in accordance with the requirements of GOST, only metal pads and junction boxes are installed. With external devices of plastic are permissible, but they must be installed on metal plates.
Selection of input cable and circuit breaker at input
A great importance in ensuring the safety of electrical wiring is the correct input of electricians inside the house. When choosing a cable and a circuit breaker, you should take into account that in the future the load on it will only be increase - the number of household appliances and units that are used at home, over time increases.
The electrician's task is to select a cable that will ensure the use of electrical appliances without the risk of overvoltage of the lead-in conductor. Optimal placement of the input circuit breaker (AB) is considered to be its location in front of the meter. Its task is to disconnect the internal network with excessive current consumption, for example, with a short circuit. But at the same time, it must not be switched off at the maximum permissible load. In order to calculate the nominal value of the input AB independently, use the formula Inom = P / U x cos (f), where Inom is the rated current, P - total power of all devices, cos (f) - power factor, which for most electrical appliances can be considered equal to unit. To the obtained value of the rated current, 10% is added and a circuit breaker is selected with respect to it. Most often in a private house there is enough AB with a nominal value of 25 A.
Three-phase power of a private house
The vast majority of wooden houses use single-phase food. But if it is planned to use high-power units - for example, powerful electric welding or woodworking machines - three-phase current is needed. In this case, it is necessary to consult a specialist for the calculation of the adjusting devices. Calculations are made by more complex formulas and in relation to a specific situation.
Installation of electrical wiring by own hands in a wooden house
In the presence of an agreed project, carried out in accordance with all legislative norms, it is possible to conduct the installation of electrical wiring independently. To do this, you need to stock up on the necessary tools and materials, as well as familiarize yourself with the safety rules. Let's consider the main stages of house electrification.
Installation of the switchboard
The switchboard is the main point of electric power management. It is a cabinet, inside of which there are devices for monitoring and recording the current consumed. Can be made of metal or made of dielectric plastic.
The shield is mounted in an easy to use place, at a height of, up to, m from the floor surface. Most often it is located near the entrance door, so that you can turn off the electricity while leaving, and turn back to turn it on. From the power lines to the shield, an input cable is fed, then the electricity is distributed throughout the house. Inside the shield is installed:
- electricity consumption meter;
- turn-off automatics on DIN-rail;
- RCD (protective shutdown device);
- bus for output of ground and zero circuit.
An introductory circuit breaker can also be placed here, but it is also practiced to place it outside the house at the point where the air line connects to the home network. This option is not without sense, since the risk of excessive load on the lead-in cable is significantly reduced.
Installation of the switchboard is made first. Particular attention should be given to the selection of automation, using proven and reliable brands of devices from renowned manufacturers.
The switchboard is not recommended for installation in places with high humidity.
Video: overview of the switchboard for a private house
Cable entry inside the room
There are two options for cable entry from the power line to the house.
- Air method, which uses a self-supporting insulated conductor.
- Underground mode, when the cable is brought into the room from under the ground.
The first option is more common because of the speed and economy. The second costs more, but it has a number of advantages, such as the long service life and independence from atmospheric cataclysms.
In any case, the rules require the cable to enter a wooden house through a metal thick-walled (from, to, mm) pipe. The inside of it should be painted or galvanized, and the installation is made at an angle of 3-5 degrees to the horizontal plane, so that the resulting condensate can freely flow out (GOST R 50571.15-97 (IEC 364-552) 93): n. 522.3.2).
The installation of the metal sleeve and cable entry is always carried out from the outside of the wall. The installer must have the appropriate qualifications and admission. Most often this work is performed by employees of the energy supply organization.
Video: cable entry into the house and connection to the shield
Installation of switches and sockets
In wooden buildings there are certain nuances in the installation of switches and sockets.
- If concealed wiring is installed, the sub-grid, in accordance with the UE, should only be metallic. Despite the fact that the contact pair of modern switches is reliably hidden inside the plastic (or ceramic) cap, a micro-spark appears every time the device is used. The same happens in the outlet while the plug is plugged into it. In ordinary stone walls, this is not dangerous. But in dry wood, in which wood dust can also accumulate, such a spark can lead to the most unintended consequences.
- For external wiring, when cables are suitable for outlets and switches on the wall surface, use is made of dielectric plates separating the device from the wood. To neglect it is not necessary, it is better to think in advance about how to make such a lining aesthetic. In retail chains, there is a wide variety of protective areas for every taste and color from plastic to metal. According to the rules, the size of the site should cover the wall by 10 cm on each side (it is considered from the socle).
Otherwise, the installation of the sockets and switches is no different from the installation in a stone structure.
- First, marking the wall. It is best to use the building level or laser level.
- Next, the podzroetniki or protective areas are installed.
- On them the socle of the device is mounted.
- After connecting to the wires, an outer casing is attached.
All of the above applies to junction boxes. It is recommended to design the wiring in such a way as to minimize the amount of wiring.
Based on the same prerequisites of increased fire hazard, the connection of conductors in wooden structures is recommended to be carried out with the help of factory terminal blocks. Screws are allowed only in case of additional soldering of current-carrying cores and with the use of plastic caps.
Grounding and installation of RCDs
The device of protective switching-off (RCD) is intended for protection of the person (and domestic animals) from electric shock if there is a possible leakage on the damaged insulation or the metal housing of household devices.
The device is able to detect a minimal leak and react to it by opening the circuit. The sensitivity level depends on the brand of the device. The choice is made by the main parameter - the leakage current, which is expressed in milliamperes. If the RCD is included in the entire house protection circuit, a leakage current of 30 mA is sufficient. If the device is designed to protect individual rooms, for example, a bathroom or a bathroom, a higher sensitivity of 10 mA is selected. The RCD is installed in the switchboard. The connection diagram provides for the location of the RCD in front of the circuit breakers.
Video: connection of circuit breaker and RCD
The same tasks are assigned to the grounding of all electrical installations inside the house. Separately, we can say about the grounding device. In order to ensure that the system of tapping of wandering currents is working properly, it is necessary to follow the recommendations for self-adjusting the earthing strip.
To do this, you need a metal armature of three meters length and three-meter length of corners.
- First, a pit with a depth of 50 cm of a triangular shape is excavated.
- In every corner, the reinforcement bars are driven in full length. The distance between them should be 1 m.
- Corners are welded to the ends of the fittings. As a result, an integral structure should be obtained.
- To one corner is fastened a threaded connection conductor, which is displayed on the switchboard.
Do not forget about the seasonal expansion and contraction of the metal under the influence of changing air temperature.
To prevent the grounding bus from breaking, a "compensation hump" is used in it, which is designed to absorb thermal changes.
Ways of open posting posting
In practice, three types of external wiring are used in wooden houses:
- Harness in corrugation. Cables are launched inside a plastic or metal corrugated hose. Advantage of such wiring is low cost of materials and quick installation. On the ceilings and walls of the corrugation is fastened with special clips. The disadvantage is the ability of corrugated sleeves to accumulate dust, which is difficult to remove from them. In addition, over time, the wiring can sag, and it needs to be tightened.
- Wiring in the cable channels. One of the most popular types of wiring today. This is due to the fact that in recent years, manufacturers have started to produce a large assortment connecting hardware, with which you can without any damage to the appearance of a wire in any configuration. The main advantage of this type of wiring is affordability, speed of installation and a high level of maintainability. This cable channels favorably differ from the corrugation, which in case of repair wiring will have to be replaced completely. The big advantage of wiring in cable channels is the availability of cables and the possibility of updating them if necessary. The only thing to remember when installing cable channels is shrinkage of the house. Freshly built wooden houses give a significant (up to 5% per year) shrinkage. And this means that the wiring lines can be deformed.
- Posting in retro style. Quite a popular trend in interior design. It consists in the fact that the wires are fixed to the walls with the help of ceramic insulators by an open method. The cable twists in the manner of a twisted pair and in this form extends to the lamps or sockets. The solution is not new, so laid the wires in residential buildings even 60-70 years ago, but at the same time it is ideal Complies with safety standards - the cable does not touch the wall, staying at a distance of 10 mm from surface.
The choice entirely depends on the aesthetic inclinations of the inhabitants of the house. On sale are all the necessary materials to realize their preferences in terms of design solutions.
Video: outdoor wiring in a cable channel in a wooden house
Concealed wiring in a wooden house
If for any reasons the customer is not satisfied with the external location of the wiring in the house, the cable is bred in a hidden way. In a wooden structure, this is a rather laborious and painstaking procedure. Each wire, regardless of its thickness, must be packed in a metal tube. The receptacles and junction boxes must also be made of metal. It is supposed to protect the pipes from corrosion. To do this, they must be painted from the inside with moisture-resistant enamels, and to drain the condensate through certain intervals, drill small holes. For the same purpose, the pipe must be placed under a slope, so that moisture droplets can flow out. To avoid damage to insulation, the ends of the pipes are cleaned from sharp burrs and additionally equipped with plastic tips.
- The optimum material for such a wiring is a copper pipe. Its cost is quite high, but thanks to the plasticity of the metal, bends can be made without special equipment. Steel pipe is much cheaper, and for giving it the necessary form, threaded adapters and drifts are provided.
- If the wiring is installed at the construction stage, concealing it in the walls is simplified. Especially if it's a frame structure. In the houses of logs or timber, all the wiring channels are cut in the walls after their erection.
- Another way allowed by the standards of electrical insulation for wooden buildings is to locate the wiring inside the plaster laid on top of the wood. This method was practiced in the old buildings - the log was shredded with shingles (plywood fittings) and a layer of cement plaster was poured. According to the rules, the layer of plaster in this case should be 10 mm from all sides. A modern analogue of this technology is the lining of a wooden wall with gypsum plasterboard, which is essentially a dry plaster. At a standard thickness of a sheet gypsum cardboard in 1, mm to cover a wall it is necessary in two layers.
The big disadvantage of hidden wiring in the conditions of a wooden structure is the inaccessibility of cables. If there is any problem, replacing the old cable with a new one will be very difficult. Nevertheless, this kind of posting has its fans. Especially among designers, who are primarily concerned with the aesthetic solution of the home.
Video: concealed wiring in a wooden door
After completing the installation, the customer should be invited to the staff of the electrical laboratory. The purpose of the test is to measure the resistance of the system as a whole, earth resistance and check all automation: RCDs, circuit breakers, current flow meter. If all the parameters correspond to the norm, the customer receives a protocol signed by the responsible person. This document is presented to the servicing company when concluding an agreement for the supply of electricity to the facility.
If you independently perform the installation of wiring, it is important to follow personal security measures. Electric shock can cause irreparable harm to health, cause death. Installation is carried out only when the mains power is disconnected. Commissioning of equipment is carried out in the presence of an authorized representative of the project organization..