How to connect a construction site to electricity during construction

Most types of construction work require electricity. This applies not only to power tools, but also to lighting of workplaces, including in a construction trailer for workers in a temporary camp. Thus, it turns out that without preliminary electrical installation work and laying electrical wiring, it makes no sense to begin construction of objects. Major electrical work at the start of construction runs the risk of requiring significant changes as the work progresses. Therefore, the most optimal option is a temporary power supply to the construction site for the construction period, but taking into account the electrical design in accordance with current electrical safety requirements and other regulatory documents, including PUE and SNIP.

Organization of construction.

The scope of work is proposed to be completed in three stages:
1. Preparatory.

2. Construction part.

3. Installation part.

The preparatory stage of work includes clearing the route and laying out turning angles. At this stage, the issue of delivery of materials to the route must be resolved.

The construction part includes drilling pits for supports, installation of reinforced concrete supports, grounding of supports and KTPN, installation of a foundation for KTPN, installation of KTPN fence posts.

The installation part includes the installation of cables and wires, metal structures, disconnectors, transformer transformers, checking and putting cable power lines and transformer transformers into operation.

Restrictions when carrying out excavation, emergency restoration and other work

Restrictions have been introduced when carrying out excavation, emergency restoration and other work. A ban has been introduced on:

• Carrying out work outside the territory specified in the order (permit).
• Preparation of mortar and concrete on the roadways of streets and highways.
• Pumping water from wells, trenches, pits directly onto sidewalks and roadways of streets and highways, as well as placing soil and construction and demolition waste, burning and burying waste in the above-mentioned areas.
• Obstructing the passage of vehicles at entrances and exits and passages into courtyards.
• Contamination of the soil layer in the work area.

Assembling an electricity metering circuit

Please note that the circuit in your project may be very different in construction and the electrical products used from the one demonstrated here. Also, for neatness, a PVC mounting box was used, the use of which is not at all necessary. The machines, the DIF-automatic machine and the meter are installed on a DIN rail, which is attached to the body of the electricity metering box with self-tapping screws

The peculiarity of the above diagram is the presence of an automatic circuit breaker and a cable for future connection of the house; this may not be present in the standard scheme. If you have provided for the presence of these components, then remember that they will be connected when the house is built and you connect it to the electrical network. This procedure will require a new project and appropriate organizational arrangements.

The machines, the DIF-automatic machine and the meter are installed on a DIN rail, which is attached to the body of the electricity metering box with self-tapping screws. The peculiarity of the above diagram is the presence of an automatic circuit breaker and a cable for future connection of the house; this may not be present in the standard scheme. If you have provided for the presence of these components, then remember that they will be connected when the house is built and you connect it to the electrical network. This procedure will require a new project and appropriate organizational arrangements.

Help with advice on cable support on site

To do this, a shield with anti-vandal protection and IP class is installed. Its dimensions must be such that it is possible to install a meter, protective devices and grounding buses. You should also find a place to install a backup power supply.

An autonomous generator is a source of stable electricity supply to a construction site. Its installation does not require coordination and connection to power lines, as well as the cost of wiring cables to the power source. The only drawback is the high cost of the equipment.

Typically, generators are used at the first stage of construction, while temporary power supply is being arranged and connected.

Temporary supply of electricity to the site

When all organizational issues have been resolved, you can proceed to determining the location of the input panel. If the site is located further than 25 meters from the power line, the installation of another additional support is required in accordance with the requirements of the PUE. According to the rules, the shield should be installed at the border or on the territory of the applicant.

Cables and supports are led from the panel to the construction sites. Temporary connection to power grids during the construction period is accompanied by the emergence of new routes for laying cables of a certain brand and length.

All instructions Standard instructions on labor protection for workers by position and individual professions. Standard instructions on labor protection for employees of an organization for certain types of work. Instructions on labor protection for employees of the organization by position and individual professions.

All this data should be reflected on the diagram before they are laid. There are several types of connection schemes - radial, ring, mixed wiring. Radial design is distinguished by power supply from one input circuit breaker, from which electricity is supplied via cables to power plants and lighting devices.

The allocated power usually depends on the Technical Conditions that are provided to the developer.

Methods for electrifying a construction site

It is important here how far you are from the lines, what their condition is, what the power of the substation is, how many consumers are already connected. At a construction site, of course, you can get by with generators, but what then? Theoretically, the volume of energy consumed by one subscriber is not limited by law, but there are technical restrictions

Also, meters with built-in power limiters can be used for these purposes. Secondly, tariffs.

Input design

One of our articles has already talked about self-assembly of a three-phase switchboard on a personal plot. The technology for assembling this shield is not much different; let us recall the important points.

The metering device and protection devices, such as a circuit breaker, RCD, must be located in a sealed box that prevents the ingress of moisture and foreign objects. It is also necessary to organize a grounding device, ground the shield and re-ground the zero from the overhead power line (PUE chapter 1.7, clause 1.7.61), organize a TN-CS system (PUE chapter 7.1, clause 7.1.13). Do not forget to take all safety measures to carry out the work.

Cable laying is possible both in trenches, in places where it will not experience loads from vehicles passing over it, or by hanging it on a cable at a safe height. We recommend studying the technology of installing cable wiring in the country.

Installation of main components of substation equipment

Electrical units are delivered to the construction site and installed indoors. They are bolted together, connected to each other through busbars, then cables are laid and the equipment is inspected.

In the premises where installation is carried out, finishing measures must be completed. After this, cable channels are laid in accordance with the drawings. For closed devices, covering with cement screeds and slabs is provided. High voltage input is carried out both through underground cables in the provided channels and through overhead lines.

Power transformers can occupy several rooms, which must be provided for in the design solution. Moreover, during the construction of a substation, the possibility of attaching the transformer directly to the foundation or to a load-bearing substrate must be technically thought out. A separate room is provided for the installation of distribution devices. The neutral of electrical installations is connected to the grounding device by welding. For grounding, special buses are pre-organized in the form of strips with a cross-section of 40 x 4 mm. From them a conclusion is made to the transformer.

General concept

An electrical network is a collection of individual elements subordinate to a common task. These include:

• power lines (power lines);
• substations (SS);
• points: distribution points (RP);
• partitioning (SP).

Each of these elements performs its own function. For example, the PS is designed to change the voltage in the network, and the SP is designed to turn it off in an emergency. RP - distributes energy within a separate network element. This equipment is closest to the consumer.

Attention: electrical networks are created for the purpose of transmitting electricity (EE) from producer to consumer

Temporary supply of electricity to the site

Temporary electricity connection to the site

The provision of temporary power supply to the site is associated with a number of organizational issues. The connection is made to existing highways. Depending on the location of the site, the best method of temporary power supply is selected. The choice depends on the following criteria:

• distance of the nearest power line;
• type of object;
• required power;
• type of network.

If connected to an existing electrical network, you should contact the energy sales organization to find out the connection procedure and other conditions. For a stand-alone generator, you do not need to request permission. How much the entire temporary power supply work will cost and how much time it will take depends on the chosen scheme.

Electrical safety and precautions

According to the requirements of the PUE (7th edition), electrical equipment is classified by a safe voltage that does not exceed 50 volts AC and 120 volts DC. For devices that are located outside and in the danger zone, low voltage is supplied (for external installations - 12 volts at direct current and 30 at alternating current.

Standards for the design of electrical installations at construction sites and similar ones imply ensuring a safe voltage level (BN) of 25/60 volts (DC/AC), provided that these installations use “automatic circuit breakers” to turn off the power supply as protection, then the shutdown time must comply with PUE standards ( Table 1.7.11 of Chapter 1.7).

To provide increased protection for the electrical network with a current of up to 32 amperes, when connecting electricity, an RCD with a switch with a voltage of up to 30 mA is used. Also control elements - circuit breakers, RCDs, starting devices, contactors, etc. must ensure the disconnection of all phase and neutral conductors.

Types of connection of power lines to a low-voltage complete installation of a construction site:

• through plugs;
• directly to the distributor;
• using an input device (terminal cabinet).

The low-voltage supply network introduces and distributes electricity to the site using a three-phase AC system with a solidly grounded neutral at 380/220 amperage and a frequency of 50 hertz and a single-phase 220-volt AC system with a maximum consumption of 63 A.

There are the following types of low-voltage complete devices:

1. NKU input and distribution.
2. Main distribution NKU SP.
3. Transformer NKU SP.
4. Plug.

By method of use:

• for input and measurement of electricity consumption from transformers, generators or from public networks;
• the main distribution room for receiving electricity, which is used for lighting, powering residential premises, welding devices, etc.
• Distribution NKU: receiving and distributing energy from larger low-voltage installations, as well as for connecting power supplies.
• Low-voltage device for transformers - reducing the voltage in the network to the required level.
• Plug device - receiving electricity through an extension cord from any other distribution device.

Elements of low-voltage devices are placed in special cabinets (floor-mounted, wall-mounted); the devices are either stationary or mobile. For example, an NKU for input requires a separate place for measuring and accounting equipment and elements that record and indicate the presence of current in the network. The measuring unit must be sealed. In addition, in such devices, the internal wiring must be securely closed from outsiders, while providing access to meters and toggle switches, with appropriate inscriptions, and an image of the electrical circuit is placed on the cabinet door. Wires into the NKU are introduced either from above or from below; plastic or rubber insulation is allowed. The devices are manufactured with rubber (with IP 54 protection) or plastic seals and cable fastenings in the device body.

Below you can use the online calculator to calculate the cost of designing power supply networks:

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Organizational events

Depending on the location of the site where construction is taking place, a method for supplying temporary power supply is selected. The choice of cable routing type is influenced by the following points:

• Distance from power lines.
• Type of object: residential building, warehouse or production workshop.
• Estimated power consumption.
• Choice of network: single-phase or three-phase.
• Condition of the nearest overhead power line.

Based on these options, the best method for installing temporary power supply at the construction site is selected. This may be a connection to existing networks or installation of an autonomous power generator. When connecting to the power grid, it is better to individually clarify the calculation procedure and other conditions with the power grid and energy sales organization.

TECHNICAL CIRCULAR

About temporary power supply schemes for construction sites

The requirements of this circular apply to temporary electrical installations intended for:

– construction of new buildings;

– repair, reconstruction, expansion or demolition of existing buildings;

– municipal engineering works;

– earthworks;

– other works of a similar type.

Electrical installations of these facilities are subject to increased electrical safety requirements, taking into account the specifics of electrical installations at construction sites.

In addition to the general requirements established by Chapter 1.7 of the PUE “Grounding and protective safety measures” and GOST R 51321.1 (IEC 60439-1) “Complete low-voltage distribution and control devices. Part 1. Devices tested in whole or in part. General technical requirements and test methods”, when developing temporary power supply schemes for construction sites, one should take into account the special requirements established by GOST R 50571.23 (IEC 60364-7-704) “Electrical installations of buildings. Requirements for special electrical installations. Electrical installations of construction sites" and GOST R 51321.4 (IEC 60439-4) "Complete low-voltage distribution and control devices. Part 4. Additional technical requirements and test methods for distribution and control devices for construction sites."

Until the release of special regulatory documents regulating the requirements for electrical installations of construction sites, it is proposed to be guided by the following:

– for the specified settings, the permissible touch voltage is set to 25 V AC and 60 V DC;

– the maximum permissible time for automatic power off of portable (mobile) devices at a phase voltage of 220 V is reduced to 0.2 s;

– to ensure protection when a phase wire is shorted to ground, the parameters of the grounding device according to clause 1.7.101 of the PUE are recalculated in accordance with the requirements of clause 413.1.3.7 GOST R 50571.3 (IEC 364-4-41) “Electrical installations of buildings. Part 4. Security requirements. Protection against electric shock", for permissible touch voltage 25 V, value RE

for construction sites it is assumed to be 20 ohms;

– in addition to the requirements of Chapter 1.7 of the Electrical Installation Code, the electrical installation must have a protective grounding system that provides protection in the event of a ground fault in the electrical installation above 1 kV in accordance with the requirements of GOST R 50571.18 (IEC 60364-4-442) “Electrical installations of buildings. Part 4. Security requirements. Chapter. 44. Surge protection. Section 442. Protection of electrical installations up to 1 kV from overvoltages caused by ground faults in electrical installations above 1 kV.” If, during a single-phase ground fault at a 6-10/0.4 kV transformer substation, the voltage on the ground electrode exceeds 33.5 V (corresponds to a permissible touch voltage of 25 V), the transformer neutral must be grounded to a separate ground electrode;

– plug sockets must be protected by a residual current device with a rated residual current of up to 30 mA or by using safety extra-low voltage;

– to implement power supply schemes, special low-voltage complete devices for construction sites (NKU SP) should be used;

– NKU SP must have a certificate of conformity in accordance with GOST R 51321.1 and GOST R 51321.4;

– the degree of protection of the NKU SP shells is determined by the conditions of use in accordance with GOST 14254, but not lower than IP43 with the door closed and not lower than IP21 with the door open; When installed outdoors without a canopy, the degree of protection of the NKU SP shell is assumed to be no lower than IP54.

(Journal "Occupational Safety in Industry", issue 3/2006)

Reference information on organizing temporary power supply to a construction site

The possibility and cost of power supply to a construction site is greatly influenced by its location and distance from nearby power generation facilities. Legal power supply to a construction site can be provided by the following resources:

1. Autonomous power supply (generator sets)
2. Indirect connection through the power grid of nearby enterprises
3. Connection to electrical lines and devices (transformer substations, distribution points) of the electrical networks of the nearest network organization

Autonomous power supply is convenient because there is no need for approvals and dependence on anyone, but it has disadvantages in the form of the high cost of the electricity received and its limited power. Generator power supply is used in case of small energy needs of a construction site (for example, private country houses). In the case of industrial construction, power supply with a generator is used as a last resort - when it is necessary to urgently resume construction without the possibility of connecting to the power grid.

In the case of indirect connection or connection to the electrical networks of a network organization, in addition to electrical installation work on the physical connection of lines, it will be necessary to obtain permits for temporary power supply. The procedure for approving temporary power supply is practically no different from the permanent connection of the facility to power supply networks and looks like this:

• Calculation of the planned load and calculation of the required electrical power. Development of internal and external power supply schemes
• Drawing up an application for technological connection to the electrical networks of the nearest network organization (indicating the required power, voltage, reliability level, etc.)
• Obtaining Technical Conditions (TU) of the grid organization (Lenenergo, etc.) for permanent and temporary power supply
• Development of a temporary power supply project for a construction site, in accordance with the received specifications
• Coordination of the external power supply project, load calculation table, metering unit with the network organization
• Carrying out electrical installation work on site according to the project (installation of an ASU electrical installation, laying construction cable lines to the connection point, etc.)
• Conducting an examination of the electrical installation and obtaining the appropriate Certificates and approval from SZ Rostekhnadzor
• Conclusion of an agreement for temporary power supply to a construction site with an energy supply company (JSC Petersburg Supply Company, RKS-Energo, etc.)

Often, in parallel with the organization of temporary power supply, it is advisable to launch the process of coordinating the permanent connection of the facility to the power grid, which will save time in the future.

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Providing a construction site with electricity is one of the determining factors in the industrialization and mechanization of construction and installation work. Therefore, in order to organize an uninterrupted power supply for construction when designing a construction plan, it is necessary to develop a special section of the project.

The temporary power supply system for construction is designed in the sequence provided by the diagram in Fig. 3.6 b.

The calculation of electrical loads is carried out using various methods: by specific electrical power and by the installed power of pantographs.

The first method is to calculate the loads for the development of a site-wide construction plan as part of the PIC. The method is based on statistical data on electricity consumption per 1 million rubles of the annual volume of construction and installation work. It depends on the type of construction and its industry structure.

In housing and civil construction, per 1 million rubles there is an average of 70 to 205 kVA of specific electrical power, related to the power of power transformers, with the annual volume of construction and installation work (in 1984 prices) from 3-5 million to 0.5 million. rub., respectively.

In industrial construction, this figure ranges from 60 kVA to 400 kVA.

The design power of transformers is determined by the formula:

,

where: C – annual volume of construction and installation work, determined according to the financing schedule during the period of highest intensity of work, million rubles;

p – specific power, kVA/million rubles;

kt – coefficient taking into account the construction area.

When designing PPR, loads are calculated based on the installed power of electrical receivers - electricity consumers. The most accurate method is to calculate the power required to ensure the operation of construction machines - Рс, the performance of construction and installation work - Рт, lighting of an external construction site - Ron and internal premises - Rov.

Loads are calculated using the formula

,

where: Ks, Kt, Ko – demand coefficients, depending on the number of consumers table. 3.3.

cosφ – power factor, depending on the number and load of power consumers – 0.65 – 075.

1.1 – coefficient that takes into account network losses.

The power of electricity consumers (kW) is determined:

power plants Рс and for technological processes Рт - according to reference books and catalogues; lighting devices; Rov, Ron - according to specific power indicators per illuminated area (Table 3.3., 3.4.).

Conversion of power in kVA to installed power in kW is carried out using the formula:

Table 3.3.

Values ​​of demand coefficients Ks and power cosφ

Table 3.4.

Specific power indicators

The sources of power supply at the construction site are stationary or mobile transformer substations. Stationary transformer substations are constructed during the preparatory period of construction and are designed for power from 10 to 1800 kVA. Mobile transformer substations are used at facilities that are not provided with a constant power supply. They are connected to high voltage sources of the power system (operating stationary transformer substation) via cable or overhead line. Characteristics of some types of mobile transformer substations are given in Table. 3.5.

Table 3.5.

Characteristics of complete stationary transformer substations

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Date added: 2016-12-06; | Copyright infringement | Sayings for students

Some nuances of internal installation

Posting is created in several cases:

• during primary construction;
• reconstruction;
• major repairs;
• after emergencies.

Attention: in some situations, temporary networks are installed. But they will need to be replaced after a certain time. It is prohibited to partially replace wires or individual elements during reconstruction or repair.

Because of this, strands placed in the wall can overheat and create a fire hazard. In addition, previously aluminum cable was used in residential premises. This is a fragile material that is not recommended to be touched

It is prohibited to partially replace wires or individual elements during reconstruction or repair. Because of this, strands placed in the wall can overheat and create a fire hazard. In addition, previously aluminum cable was used in residential premises. This is a brittle material that is not recommended to be touched.

Internal wiring diagram

If the installation of external electrical wiring can only be carried out by certified electricians, then with internal wiring everything is simpler. In his own home, a citizen himself is able to change wires and install components. However, this is associated with a danger to life both during installation and when using electrical appliances.

Work begins with drawing up a design for the electrical system. It includes all the proposed nodes, their location, etc.

Important attention should be paid to calculating the planned load

Attention: a load exceeding 5 kW per line is not allowed. That is, it is necessary to distribute the devices evenly. If equipment with high power consumption is used in the room, a separate line is laid to it. Experts recommend selecting switches with built-in rheostats

This will allow you to regulate the load during their use (save electricity). Euro sockets are more suitable for modern premises

If equipment with high power consumption is used in the room, a separate line is laid to it. Experts recommend selecting switches with built-in rheostats. This will allow you to regulate the load during their use (save electricity). Euro sockets are more suitable for modern premises

They allow you not to think about contacts when choosing equipment. Particular attention should be paid to the electrical panel. High power electrical equipment is grounded and equipped with protection devices (in case of a short circuit).

Important: installation of the electrical panel is carried out in accordance with all technical rules. It should be entrusted to a specialist to avoid dangerous mistakes. https://www.youtube.com/embed/xQ_TE8oGJ9I

General concept

An electrical network is a collection of individual elements subordinate to a common task. These include:

• power lines (power lines);
• substations (SS);
• points: distribution points (RP);
• partitioning (SP).

Each of these elements performs its own function. For example, the PS is designed to change the voltage in the network, and the SP is designed to turn it off in an emergency. RP - distributes energy within a separate network element. This equipment is closest to the consumer.

Attention: electrical networks are created for the purpose of transmitting electricity (EE) from producer to consumer

Features of connection to existing electrical networks

The first situation we will consider is that construction is taking place in close proximity to your own home. The method of electrification from an already registered input is considered less expensive and more preferable. During construction work, electricity that is already present at the site is consumed and payment for it occurs in accordance with a previously concluded agreement. This option is suitable for temporary power supply to a private home.

After the construction of a new facility and, possibly, dismantling of old buildings, there will be a need to re-register the contract with the supplying organization.

To do this you need:

1. Indicate the estimated power consumption.
2. Obtain technical specifications and connection point for input from the organization.
3. Order project documentation.
4. The project must be coordinated with the State Technical Supervision Authority.
5. Perform electrical installation work.
6. Call an electrical laboratory to evaluate and draw up a test report.
7. Conclude an agreement with the energy supply company and commission the facility.

All documents are provided in the photo:

Please note that in order to make temporary electrical wiring, you will also need to complete this package of documents.

In cases where the construction site is located far from power lines, the construction of a new overhead line (or cable laying) will be required. To do this, you need to contact the power grid organization and write an application for a technological connection, after which you should be given technical specifications. After completing the documents, you must fulfill the conditions of the technical specifications and contact the network organization again to connect the shield to the pipe stand and seal the metering devices. More details about the connection are described in the video:

Commissioning at the facility must be done as for permanent operation. To do this, you need to install an external vandal-proof shield with protection class IP54. The box is installed in such dimensions that it is possible to install a meter and protection devices, sockets and grounding bars. It is also necessary to provide space for backup power supply.

When building within a non-profit partnership, the cost of services for collective connections is much cheaper for country, gardening and garage cooperatives. They have a transformer substation to which it is possible to connect. Many teams have already established themselves and formed. Repairs and modernization of equipment were carried out at their expense, installation of supports, transformers, laying of overhead lines. Newly emerging developers may be presented with monetary compensation for work already carried out and modernization of some equipment.

Another situation that I would like to consider is temporary power supply to a private house from neighbors. If, due to reasons beyond your control, electrification is being adjusted, but deadlines are running out, then it’s worth reaching an agreement with your neighbors. If such a kind person is found, the power supply is connected through an additional metering device for the period of repair and construction. The amount of power supplied is determined in advance (control by metering device) and the installation of a protective limiting device. This is the easiest way to make temporary wiring to the site.

By the way, I would like to move away from the topic a little and invite you to familiarize yourself with the methods of temporary power supply to an apartment. Find out what you can do if the lights in your apartment are turned off for non-payment.

Separately, you need to consider such a method of supplying electricity as connecting an electric generator. From a technical point of view, generator sets provide high-quality electricity. Builders use them at their own discretion and do not depend on anyone. The disadvantage is the high cost of the electricity produced. This type of supply is mainly resorted to at the beginning of construction, when there is a hitch with temporary supplies at the stage of paperwork.

Precautionary measures

Construction is a constant movement, movement, which can sometimes result in completely unforeseen risks. For this reason, special requirements are imposed on the temporary supply of electrical energy, since such a factor is welcome (the adverse effects of the atmosphere on electrical installations and their parts). Related workers with a low approval group or lack of required qualifications, presence of caustic and flammable materials on the construction site, lack of grounding and potential equalization elements at devices.

When lighting, you should choose devices with protection class IP54 so that you can install them in an open space. By following the recommendations and rules from the PUE, the risks of injury will be reduced to zero. Finally, we recommend watching a video that demonstrates a panel for temporarily supplying an area with electricity.

Electrical in residential premises

• Electrical installation in the apartment
• Electrician in a one-room apartment
• Electrician in a two-room apartment
• Electrician in a three-room apartment
• Electrician in a four-room apartment
• Electrical installation at the dacha
• Electrical installation in a private house
• Electrical installation in a country house
• Electrical installation in a wooden house
• Electrics in a house made of SIP panels
• Electrical installation in the garage
• Electrical installation in a cottage
• Electrical installation in a townhouse
• Electrics in baths and saunas
• Electrics in the cabin
• Electrician in a panel house
• Electrician in a log house
• Electrician in a stone and brick house
• Replacement of electrics in Khrushchevka
• Replacement of electrics in "Stalinka"
• Replacing electrical wiring in a panel house
• Temporary power supply
• Installation of hidden electrical wiring
• Hidden wiring in a wooden house

General requirements. Electricity supply

7.1.13. Electrical receivers must be powered from a 380/220 V network with a TN-S or TN-CS grounding system.

When reconstructing residential and public buildings with a network voltage of 220/127 V or 3 x 220 V, the network should be switched to a voltage of 380/220 V with a TN-S or TN-CS grounding system.

7.1.14. External power supply to buildings must meet the requirements of Chapter 1.2.

7.1.15. In dormitories of various institutions, in schools and other educational institutions, etc. the construction of built-in and attached substations is not allowed.

In residential buildings, in exceptional cases, it is allowed to place built-in and attached substations using dry-type transformers in agreement with state supervisory authorities, while sanitary requirements for limiting noise and vibration levels must be fully met in accordance with current standards.

The construction and placement of built-in, attached and free-standing substations must be carried out in accordance with the requirements of the chapters of Section. 4.

7.1.16. It is recommended that power and lighting electrical receivers be powered from the same transformers.

7.1.17. The location and layout of transformer substations must provide for the possibility of round-the-clock unhindered access to them for personnel of the energy supply organization.

7.1.18. Power supply for safety lighting and evacuation lighting must be carried out in accordance with the requirements of Chapter. 6.1 and 6.2, as well as SNiP 23-05-95 “Natural and artificial lighting”.

7.1.19. If there are elevators in the building, which are also intended for transporting fire departments, their power supply must be provided in accordance with the requirements of Chapter. 7.4.

7.1.20. Electrical networks of buildings must be designed to power advertising lighting, shop windows, facades, illumination, outdoor, fire-fighting devices, dispatch systems, local television networks, light indicators of fire hydrants, safety signs, bell and other alarms, light fencing lights, etc., in in accordance with the design specifications.

7.1.21. When supplying single-phase consumers of buildings from a multiphase distribution network, it is allowed for different groups of single-phase consumers to have common N and PE conductors (five-wire network) laid directly from the ASU; combining N and PE conductors (four-wire network with PEN conductor) is not allowed.

When supplying single-phase consumers from a multiphase supply network with branches from overhead lines, when the PEN conductor of the overhead line is common to groups of single-phase consumers powered from different phases, it is recommended to provide protective shutdown of consumers when the voltage exceeds the permissible limit, arising due to load asymmetry when the PEN breaks conductor. The disconnection must be carried out at the entrance to the building, for example, by influencing the independent release of the input circuit breaker using a maximum voltage relay, and both the phase (L) and neutral working (N) conductors must be disconnected.

When choosing devices and devices installed at the input, preference, other things being equal, should be given to devices and devices that remain operational when the voltage exceeds the permissible voltage, arising due to load asymmetry when the PEN or N conductor breaks, while their switching and other performance specifications may not be met.

In all cases, it is prohibited to have switching contact and non-contact elements in PE and PEN conductor circuits.

Connections that can be disassembled with a tool are allowed, as well as connectors specially designed for this purpose.

Tips for working safely with electrical equipment on a construction site

When starting to operate electrical appliances, you should consider:

• unfavorable working conditions during precipitation;
• the presence of unskilled workers according to safety rules who may be exposed to electric current;
• presence of flammable materials and flammable liquids on the site;
• lack of possibility of protective shutdown in the event of leakage currents in some electrical appliances of the old standard.

The safety of using electrical appliances can be increased through the use of isolating transformers connected to an ungrounded potential equalization system. It must connect all metal housings through cables equipped with plugs and sockets with protective contacts of the PE conductor.

The workplace in the dark should be well lit, and the light from spotlights should be used at a uniform brightness without a glare effect.

Lamps and electrical devices located outdoors must be used only with a housing that meets the IP54 protection requirement.

Construction itself already contains a list of operations that are classified as dangerous. The use of electrical energy to operate machinery and tools increases the risk of health damage

Therefore, when carrying out power supply to a construction site, it is necessary to pay increased attention to safety issues.

To conclude the presentation of the material, I would like to recommend watching a video by Pavel Sokolovsky, who completed the electrical supply of a private house with his own hands. It shows a good use case for the entry panel that was created when construction began.

If you have any unclear questions, please ask. There is a “Comments” section for this.

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Safety precautions

Only specialists with the appropriate clearance group are allowed to work

A construction site is a hazardous site, so to preserve the health and life of construction workers, safety precautions must be observed. It also applies to equipment that has special requirements. They are associated with negative environmental influences - the influence of ultraviolet radiation, weather conditions, and high humidity. Materials must be non-flammable.

There should be no caustic chemical materials at the construction site. Only specialists with appropriate qualifications and clearance groups are allowed to work.

A grounding system and potential equalization elements must be created. For this purpose, isolation transformers and a system for connecting all open enclosures using protective connectors in the socket are used. In case of high humidity, protection is carried out using an RCD.

You will need several light sources with the ability to move around the area. It is also necessary to install several lamps in the temporary room where the work will be carried out, with mechanical stability.

Development of a substation project

For the design solution, the following initial materials are preliminarily prepared:

• Technical specifications for the construction of the facility.
• Drawings and estimates.
• Construction work schedule.
• Plans for the configuration, structural design and materials of the substation.
• Information on the characteristics of electrical installations and construction mechanisms.
• Technological diagram of work processes.
• A list of installation equipment and accessories that will be used during construction.
• Schemes of underground communications indicating the route of cables, water lines and sewerage.

Based on the above documents, a project for a transformer substation is developed, which structurally describes the organizational map of work activities. It includes a comprehensive construction schedule with the order of technical operations, information on the volume of material resources, a situational plan, a transport diagram at the construction site, etc. The requirements for engineering and communication support, industrial sanitation and safety precautions are specified separately. In particular, the parameters of roads, bridges, stairs, toilets, fire extinguishing systems, etc. are described.