Open pipeless electrical wiring must be made in accordance with the requirements of SNiP III-33-76* “Rules for production and acceptance of work. Electrical devices" and "Rules for electrical installations" (PUE).

Fastening cables with a metal sheath and unprotected wires with metal brackets must be done with elastic insulating pads with a thickness of at least 0.3 mm, protruding from under the bracket on both sides by at least 1.5-2 mm.

When directly attaching unprotected wires and cables with a metal sheath to the supporting strip, string, or cable, elastic insulating pads must be installed at the fastening points between the conductors and the strip, string, or cable.

Installation of tubular wires

Unarmoured protected cables of small cross-sections (up to 16 mm2) with rubber and plastic insulation are laid mainly in the workshops of industrial enterprises, including in explosive zones of some classes. Tubular wires with a sheath of tinned steel or aluminum tape are used for laying only in rooms with a normal environment and have increased resistance to mechanical damage.

For direct installation on building foundations, cables of the AVRG, ANRG, ASRG brands with rubber insulation, AVVG, APVG brands with plastic insulation in a common sheath and protected wires of the APRF, PRF and PRFL brands are used.

Protected cables and tubular wires are laid directly on building foundations. Marking of routes and locations of panels, lamps, boxes and other elements of lighting electrical installations is carried out according to standardized dimensions: the distances between fastening points for horizontal installation should be no more than 500 mm, and for vertical installation 700... 1000 mm; fastening is carried out at a distance of 10... 15 mm from the bend of the route and 50... 100 mm from the entry into the boxes, as well as at devices, passages, etc. The height of the route from the floor level to the service area is not standardized. The bending radii of unarmored cables with a cross-section of up to 16 mm2 and tubular wires must be at least six of their outer diameters.

For single cables and wires laid along a horizontal route, marking is done with brackets with one tab placed below the wire or cable; along a vertical wall - with brackets with two legs (one is allowed); on ceilings, corners and at the end of the route (at the inputs) - also with brackets with two legs. The brackets are installed both on straight sections of the route and on turns perpendicular to the center line of the wire, individual cable or bundle.

Simultaneously with the preparation of routes for laying cable wires on site, wires are prepared in workshops: wires are straightened, cut into segments, insulation is removed from their ends, cores are bent, rings are formed at their ends, wire ends are inserted into junction boxes, connections are made, wire cores are terminated and isolation of connections, as well as checking the circuit and marking the neutral conductor.

Fastening electrical wiring from unarmored cables with small cross-sections and tubular wires to building foundations is carried out in the following ways:

1. metal brackets directly to the base;
2. on the supporting steel strip with metal strips with buckles, spot welded, or tape with buttons;
3. on the strings with bandage metal strips or polyvinyl chloride tape with buttons;
4. with bandage strips to special holders glued to the base;
5. plastic brackets.

A new fastening product is a polyethylene fastener, which consists of a base with two ears for inserting bandage tapes or jagged buckle strips. The fastener is installed on the bases using expansion dowels or dowel-nails driven in using a mandrel.

Cable fastening on steel strips or wires attached close to the base is widely used. As a carrier strip, mounting perforated strips or tapes 16 mm wide and 0.8 mm thick, strip sections from waste steel sheets are used.

The laying of tubular wires has some peculiarities due to the rigidity of the outer metal sheath. These wires are straightened using bench or manual straighteners, and bent using special pliers. When passing tubular wire through a roller straightener, the sheath seam should be positioned sideways in a straight line along its entire length. When laying the wire, the seam should be facing towards the supporting surface, and when laying horizontally along the wall, it should be facing down to avoid moisture leakage.

BIG LENINGRAD LIBRARY - ABSTRACTS -

Electrical wiring installation technology

Public Institutions Management Agency

Perm region

State Educational Institution NPO Professional Lyceum No. 32

GRADUATE QUALIFYING WORK

Electrical wiring installation technology

Kalinin Sergey Nikolaevich

Course 3, group 307

Supervisor:

Mikhailova Lyubov Efimovna

Perm, 2010

Introduction

Chapter 1. Preparing electrical wiring routes

1.1 Classification of electrical wiring

1.2 Organization of installation of electrical wiring

1.3 Wire cutting

1.4 Connection and termination of wires

1.5 Quality control of contact connections

Chapter 2. Electrical wiring installation technology

2.1 Installation of open pipeless electrical wiring

2.2 Installation of tubular wires

2.3 Installation of cable wiring

2.4 Installation with flat wires

2.5 Installation of electrical wiring on trays and boxes

2.6 Installation of electrical wiring in pipes

Chapter 3. Electrical safety precautions

Conclusion

Bibliography

INTRODUCTION

It is difficult to name an area of human production activity that would not be associated with the use of electricity. With its help, machine tools are set in motion, metals are smelted, wood is dried, electric welding is carried out, clothes are sewn, food is produced, etc. Electric energy is used in railway and urban transport, in agriculture and in everyday life. Radio communications, radar, television, research of the atomic nucleus and space exploration are unthinkable without its use.

Electric power industry is a leading branch of socialist industry, which largely determines modern scientific and technological progress.

An integral and integral part of the country's energy potential is electrification - the deep and effective introduction of electrical energy into all sectors of the national economy.

Modern electric lighting installations, including various types of electrical wiring, power plants - electric motors, busbars, cable lines - a complex complex of a wide variety of electrical devices. Their installation requires the worker to have great knowledge and professional skill. High pace, excellent quality, high labor productivity in the installation of lighting and power electrical installations are possible only if this work is carried out by educated and technically well-trained workers who have perfectly mastered the profession of an electrician in the repair and maintenance of electrical equipment. Therefore, the goal of the final qualified work “Electrical wiring installation technology” is to study in more detail the methods of laying and types of electrical wiring, installation, repair, maintenance, and the possibility of modernization in the future.

To achieve this goal, the following tasks are set:

· study methods of preparing electrical wiring routes, technical documentation, instructions.

· consider the organization of electrical wiring installation.

· learn to cut, connect, and terminate wires and cables.

· master quality control of contact connections.

· master the technology of installation and maintenance of electrical wiring

· know and follow the rules of safe work on electrical installations.

CHAPTER 1. PREPARATION OF ELECTRICAL ROUTES

1.1 Classification of electrical wiring

Electrical wiring is divided into open and hidden according to the method of execution. Open wiring is electrical wiring laid on the surface of walls, ceilings, trusses, machine frames, and hidden wiring is electrical wiring laid in the structural elements of buildings (walls, ceilings, floors, foundations, etc.) - Open electrical wiring can be stationary, mobile and portable.

External electrical wiring is laid along the outer walls of buildings and structures, under canopies, as well as between buildings on supports (no more than four spans up to 25 m each) outside streets and roads. External electrical wiring can be open, hidden, have various design forms, methods of installation, taking into account environmental conditions, safety regulations, fire safety and other factors.

1.2 Organization of installation of electrical wiring

Modern industrial installation of electrical wiring is carried out in two stages. The first stage is preparatory and procurement work outside the installation area (in the oil extraction plant) and directly at the installation sites, the second stage is laying wires along prepared routes with all connections made.

The work of the first stage of installation directly on site consists of preparing routes for laying wires, laying grounding conductors, installing embedded elements and parts for subsequent attachment of electrical equipment and electrical structures to them (if they were not provided for in the project and were not installed by the builders). These works are carried out simultaneously with general construction work but at a certain level of readiness of the facility, i.e. in accordance with the requirements of SNiP with the possibility of ensuring normal and safe conduct of electrical installation work, protection of installed equipment, cable products and electrical materials from the influence of precipitation, groundwater, low temperatures, as well as from contamination and accidental damage during further work by related organizations.

Before the start of the second stage, construction and finishing work in electrical rooms must be completely completed, including installation and testing of heating and ventilation.

Electrical installation work of the second stage in production premises is carried out simultaneously with the installation of process equipment according to a combined schedule.

Furrows, channels, niches in walls and ceilings for the installation of wiring and electrical structures in accordance with the requirements of SNiP must be provided for in construction drawings and made during the construction process or in the process of manufacturing panels and blocks at construction industry plants. The absence of channels and niches leads to the need to perform labor-intensive punching work.

Buildings and structures for electrical installation work of the second stage are accepted from construction organizations according to an act, and their readiness is checked for compliance with the requirements of SNiP, as well as the presence, size and number of installation openings provided for by the main project or the work production project for supplying electrical equipment and units of complete devices.

Preparation of electrical wiring routes includes: . (Appendix No. 1)

· marking of routes and installation locations of fasteners;

· punching work for installation of fasteners;

· fastening works (installation of fasteners in building structures - concrete, brick, cinder block).

Work on preparing electrical wiring routes is one of the most labor-intensive, especially when done manually

1.3 Wire cutting

Wire cutting involves the sequential removal of the protective, sealing, insulating and other sheaths of current-carrying conductors for the purpose of connecting or terminating them. The dimensions of the grooves depend on the diameter of the core, the method of its connection to another core or termination, the type of contact clamp of the device or plug connector and the diameter of the contact bolt. In each specific case of cutting, these dimensions are determined from reference books or by calculation.

Depending on the number of wire strands and the conditions of its cutting (for example, on the width of the routing of the ends of the wires for connections), the length of the rubber insulation remaining on the wires is determined (5... 10 mm with a small number of strands and simple routing, 50... 100 mm and more - with a large number of veins).

Depending on the adopted connection method (pressure testing, welding, etc.), the required length of the bare sections is determined, and the excess ends of the cores are cut off. (Appendix No. 2)

1.4 Connection and termination of wires

Simple twist

The easiest way to connect wires to each other is simple twisting. In order to carry it out, it is necessary to free the ends of the wire at a length of 3-5 cm from insulation and clean them to a shine with a fine file or sandpaper. The wires must be twisted very tightly, turn to turn. The ends remaining after twisting are carefully filed off with a file, and the outer turns are pressed in with pliers. (Appendix No. 3)

Bandage method

Twisting of wires can also be done using the bandage method: the stripped ends are clamped in a hand vice and wrapped with soft stripped wire (for a bandage it is best to take copper wire with a diameter of 0.6-1.5 mm; in this case, the diameter of the bandage wire should not be larger than the diameter of the cores being twisted) . The middle part of the bandage should be made staggered: if it later becomes necessary to solder this connection, the solder will better penetrate to the junction of the wires. After connection, the ends of the wires are bent at right angles, and another 8-10 turns of the bandage are applied on top. The ends of the cores remaining from the twisting are filed with a file.

Terminal connection

The technique for making connections with contact clamps is as follows. If the connection involves single-wire aluminum and stranded copper conductors, the screw terminals are equipped with a shaped washer or an asterisk washer, which prevents the conductor from being squeezed out from under the fastening;

Before connecting, the wire is stripped in the usual manner in an area corresponding to three diameters of the screw of the screw clamp plus 2-3 mm. To ensure reliable contact, the aluminum conductors can be cleaned with fine sandpaper lubricated with Vaseline. If the core is multi-wire, then at its end the individual wires are twisted into a tight flagellum.

Then, using round nose pliers or pliers, the end of the core is bent into a ring with a diameter equal to the diameter of the clamp screw. It is best to bend the ring clockwise, this will prevent it from unwinding when tightening the screw. The clamping screw or nut is tightened until the spring washer is completely compressed, and then tightened approximately another half turn.

An aluminum wire with a cross-section of 2.5 mm is connected to copper reinforcing wires (for example, to chandelier wires), single-core and multi-core, using chandelier clamps. First, the wires to be connected are cleaned with sandpaper (copper wires in the usual way, and aluminum wires under a layer of Vaseline) and lubricated with quartz-vaseline paste. After stripping, the wires are attached to the strip and pressed with screws and spring washers. The connection is inserted into the base of the chandelier clamp and closed with a lid.

1.5 Quality control of contact connections

An objective and direct method of monitoring the quality of a contact connection is to measure its contact resistance or voltage drop across it and compare the obtained data with the standard ones. Along with this, the contact connection is inspected and also measured using special tools. In especially critical cases, X-ray flaw detection, gamma flaw detection and other methods are used to control the quality of welding of switchgear busbars. Pressed contact connections are rejected if their geometric dimensions do not comply with the requirements of the installation instructions, the presence of cracks, mechanical damage or traces of corrosion on the surface of the connector, as well as if the curvature of the pressed connector is more than 3% of its length. (Appendix No. 4)

For any type of connection, the main criterion for defectiveness is the excess of the contact resistance or voltage drop at the contact section by more than 1.2 times compared to the values of the same values measured at a section of the same circuit and the same length, but without a connection. The measurement is made with a microvoltmeter or microohmmeter.

It is widely used to control the quality of pressed joints by measuring the residual thickness at the point of indentation and comparing the obtained values with the standards.

CHAPTER 2. ELECTRICAL WIRING INSTALLATION TECHNOLOGY

2.1 Installation of open pipeless electrical wiring

2.2 Installation of tubular wires

Fastening electrical wiring from unarmored cables with small cross-sections and tubular wires to building foundations is carried out in the following ways:

· metal brackets directly to the base;

· on the supporting steel strip with metal strips with buckles, spot welded, or tape with buttons;

· on the strings with bandage metal strips or polyvinyl chloride tape with buttons;

· bandage strips to special holders glued to the base;

· plastic brackets.

2.3 Installation of cable wiring

Cable electrical wiring is a type of open wiring and is used to power power and lighting electrical receivers of industrial premises, territories, driveways, warehouses, etc.

The supporting element of these wiring is a steel cable with a diameter of 3.0-6.5 mm or galvanized wire with a diameter of 5-8 mm. Using anchor and tension devices, the cable (wire) is pulled along the route. If the length of the electrical wiring is more than 6 m, then supporting strings made of galvanized wire with a diameter of 1.5-2.0 mm are installed. The sag should be no more than 100-150 mm. The wires are connected in junction boxes, and branches are made in branch boxes suspended on a supporting cable. The wire strands are connected by welding, crimping or clamping.

Cable wiring is carried out with special AVT wires, protected and unprotected insulated wires and unarmored cables suspended from a tensioned steel cable. A steel cable with a diameter of 3.0-6.5 mm or galvanized steel wire with a diameter of 5-6 mm is used. The diameter of the cable depends on the length and load on it. For end fastening of steel cables, anchor or through bolts are used. (Appendix No. 5)

Cable electrical wiring finds a wide variety of applications in the national economy and individual construction (for example, for supplying energy to a summer kitchen, outbuildings, garage, workshop, or for powering individual electrical receivers and electric-driven mechanisms that are used on the site). Wiring of this type has a number of advantages. This is, first of all, ease of installation work, installation of fasteners and reliable fastening to the bases. Cable wiring can be adapted to almost any environmental conditions.

2.4 Installation with flat wires

Wires of the brands APPV, PPV, APPVS, APPR and the like are allowed to be laid openly and hidden in dry, wet and damp rooms of a country (garden) house and in outbuildings. APPV and PPV wires have light-resistant insulation, so they can be used for open electrical wiring directly on the surfaces of fireproof walls, partitions and ceilings (covered with dry gypsum or wet plaster, covered with wallpaper). It is allowed to lay wires with polyvinyl chloride insulation on wooden and other combustible structures with a lining under them of non-combustible materials, for example, asbestos with a thickness of at least 3 mm, protruding from each side of the wire by at least 10 mm.

When concealed electrical wiring is prohibited, it is prohibited to embed wires of all brands into building structures, as well as to lay flat wires under a layer of cement mortar, when potash, soap naphtha and other components that destroy insulation and aluminum conductors are added to plaster mortars or concrete mixtures. Installation of wiring with flat wires consists of the following operations: straightening, marking routes, laying, fastening, bending and crossing, passages through walls, etc. The best way to straighten flat wires is to hold one end in a vice or secure it in another way, then pull the wire through a cloth or mitten. When straightening single-core wires with polyvinyl chloride insulation (PV, APV, etc.), it is not recommended to pull them with great force, since this may cause the insulation to move. The laying of wires is carried out in sections: apartment panel - branch box - plug socket; branch box - lamp, etc. All wire connections are made only in branch boxes; connecting wires to each other outside the boxes is not permitted.

The dimensions of the boxes should allow for a supply of ends of connecting or branch wires. For open installation, flat and small-sized branch boxes are used. They are installed without lining wooden rosettes. If metal boxes are used, bushings made of insulated material should be installed at the places where wires enter them, or additional insulation made of rubberized or polyvinyl chloride tape in 3-4 layers should be applied to the wire.

2.5 Installation of electrical wiring on trays and boxes

Installation of electrical wiring on trays and boxes compared to other installation methods (for example, in steel pipes or directly along cable structures) provides the following advantages:

· good cooling conditions for wires;

· ease of laying additional cables or wires;

· free access to wires and cables along the entire route and ease of their replacement, the ability to lay along complex routes with branches on any section of the line.

Trays are used for open laying of wires and cables in rooms where, according to current rules, wiring in steel pipes is not required (in dry, damp and hot, with a chemically active environment and fire hazard), in electrical rooms (cable mezzanines and basements), in passages behind switchboards and panels of control stations and transitions between them, on technical floors, in machine rooms and their basements, in pump and compressor rooms, as well as for intra-shop wiring above machines. Electrical wiring on trays is used in rooms with any environment, provided that wires and cables are used that are acceptable for this environment.

Trays protect wires and cables from damage and ensure their multi-layer laying.

Wires and cables with rubber and plastic insulation, with non-flammable or flame-retardant protective sheaths are laid in the trays, for example, wires of the APR, APRV, APN, APRN, APV, APP, APRTO brands and cables of the AVRG, ANRG, ASRG, AVVG, APVG brands.

Two types of trays are used: welded and made of perforated strips. The welded tray consists of two longitudinal steel profiles with perforated steel strips (cross members) welded to them every 250 mm. The length of such a tray is 2 m, width 400 or 200 mm. A perforated tray is a perforated steel strip with edges (sides) bent at right angles, 16...20 mm high. Such a structure, although rigid, can still bend slightly (for example, when installing transitions). The length of such a tray is 2 m, width 50 or 105 mm.

Holes are provided in the walls of the trays for fastening fire-resistant partitions, connectors or branches from other trays when forming a tray route. Jumpers in welded trays have perforations for attaching conductors to them. The full designation of the tray, for example NL40-P2, is deciphered as follows: supporting tray 40 cm wide, straight, 2 m long.

Corner trays NL-U45 and NL-U95 are used to form a turn in the route in a horizontal plane with radii of 45 and 95 cm. Trays with a width of 20 and 40 cm are connected by an adapter connector NL-SP, which is a 3 mm thick plate with grooves and holes. The NL-SSH hinged connector is used to connect straight trays of any type at an angle from 0 to 90° in the vertical plane, when moving from one level to another.

The fire-resistant partition, used to separate cables for different purposes in a tray, is an asbestos-cement board with parts for its installation and fastening. (Appendix No. 6)

Asbestos cement is an inorganic plastic in which the binder is Portland cement and the filler is asbestos fibers.

The process of making asbestos cement involves mixing dissolved asbestos with cement and water. The thoroughly mixed mixture obtained in this way is cast on an asbestos-cement machine into sheets, which are then pressed, dried and cut into slabs of certain sizes.

Steel boxes are used indoors instead of steel pipes intended for open and hidden wiring of supply and group lighting and power networks.

Open laying of steel boxes with direct attachment to fireproof and fire-resistant building foundations and supporting structures is allowed in dry, damp, hot and fire-hazardous rooms, in which, according to current rules, wiring in steel pipes is not required.

In steel boxes it is allowed to lay wires of one or more lighting or power electrical networks, except for mutually redundant circuits, working and emergency lighting circuits, as well as wires of lighting circuits with voltages above 42V with wires of lighting circuits with voltages up to 42V, unless the latter are enclosed in a separate insulating tube.

The boxes are rectangular profiles made of sheet steel with removable covers, which are used to assemble straight, cross-shaped, tee, corner (for turning the route in horizontal and vertical planes) and connecting sections.

The boxes are equipped with an easily removable partition, with the help of which two channels are formed for placing wires and cables of various circuits, the joint installation of which is not allowed. The removable cover of the box facilitates installation and allows you to easily replace and lay additional new wires and cables during operation.

Boxes, which require more metal to manufacture than trays, better protect wires and cables from mechanical damage, dust and other contaminants; in addition, they can be laid at any height and on workshop floors. (Appendix No. 7)

2.6 Installation of electrical wiring in pipes

Laying open and hidden electrical wiring in steel pipes requires the expenditure of scarce materials and is labor-intensive to install. Therefore, they are used to protect wires from mechanical damage, as well as to protect the insulation and wires themselves from destruction by caustic vapors and gases, moisture, dust and explosive mixtures from the environment entering the pipe.

Steel pipes used for electrical wiring are divided into three groups: ordinary water-gas pipes, lightweight pipes and thin-walled electric-welded pipes.

Before installing electrical wiring in pipes, the inner surface of the pipes is cleaned of scale and burr and the inner and outer surfaces are painted with asphalt varnish. Pipes laid in concrete are not painted on the outside for better adhesion to the concrete. Galvanized pipes are laid without painting. During installation, the normalized values of angles and bending radii of pipes are adhered to, depending on the diameter of the pipes, the number and cross-section of wires laid in them. Ordinary water and gas pipes are used only in explosive installations; light - in justified (from the point of view of saving metal) cases with open installation in dry and damp rooms; as well as for hidden installation in dry and damp rooms, in attics, in screed floors, foundations and other building elements with sealing of entry points into boxes and connecting pipes with steel threaded couplings. Thin-walled electric-welded pipes are used for open laying in dry and damp rooms without sealing the joints and insertions into boxes.

At the installation site of the electrical wiring, the pipes are laid in ready-made units, connected to each other and the wires are pulled into them. Preparation of pipe blocks in electrical assembly workshops involves the use of normalized elements in the form of angles with standard bending radii. Pipes are prepared in workshops either according to sketches or mock-ups that imitate the location of electrical receivers to which pipes with wires are connected. The connection with a threaded coupling is made with a seal of tow on red lead or a special fluoroplastic tape of the FUM brand. Such a connection is mandatory for ordinary and light water and gas pipes in explosive areas, damp, hot rooms, as well as in rooms containing vapors and gases that have a harmful effect on the insulation of wires. In dry, dust-free rooms, it is permissible to connect steel pipes with sleeves or cuffs, without sealing.

Steel pipes with an open method of installing electrical wiring are secured with brackets and clamps. It is prohibited to attach steel pipes of all types to metal structures using electric and gas welding. When laying steel pipes, certain distances must be maintained between their fastening points: no more than 2.5 m for pipes with a nominal bore of 15-20 mm, 3 m with a bore of 25-32 mm, no more than 4 m with a bore of 40-80 mm, no more than 6 m - with a passage of 100 mm. The permissible distances between the broaching boxes depend on the number of bends in the pipe line: with one – no more than 50 m; with two – no more than 40 m; with three - no more than 20 m. The choice of the diameter of the steel pipe for placing wires in it depends on their number and the diameter of the wires.

Chapter 3. Electrical safety precautions

A significant number of accidents from electric shock are due to the fact that the insulation of electrical receivers is broken. To protect people from electric shock when the insulation is damaged, at least one of the following protective measures must be applied: grounding, grounding, protective shutdown, isolation transformer, low voltage, double insulation, potential equalization.

Protective grounding is an intentional connection to the ground or its equivalent of metal non-current-carrying parts of electrical receivers (electrical installations) that may be energized. (GOST 12.1.009 – 76. SSBT. Electrical safety. Terms and definitions).

Grounding is a deliberate electrical connection of metallic non-current-carrying parts of electrical receivers (electrical installations) with the neutral point of the transformer of the supply substation of metallic non-current-carrying parts that may be energized. Grounding or grounding of electrical installations should be performed:

In all electrical installations at voltages of 380 V and above alternating current and 440 V and above direct current;

In electrical installations operated in hazardous areas, especially hazardous and outdoor installations - at a voltage above 42 V, but below 380 V AC and above 110 V, but below 440 V DC.

Premises with increased danger are characterized by the presence of one of the following conditions: dampness (>75%) or conductive dust, conductive floors, high temperature (>30°C), the possibility of simultaneous human contact with metal structures of buildings connected to the ground, apparatus, mechanisms and metal housings of electrical equipment.

Particularly hazardous premises are characterized by the presence of one of the following conditions: special dampness (>90%), a chemically active or organic environment, or two or more conditions of increased danger at the same time.

Grounding is used only in one of the electrical network systems - in power plants up to 1 kV with a solidly grounded neutral (TN). In other groups of electrical equipment, protective grounding is used.

When performing work in electrical installations, special measures (organizational, technical) must be taken to ensure electrical safety. In particular, work in electrical installations is carried out according to work orders - permits or orders.

An authorization work order is an assignment for the performance of work, drawn up on a special form of the established form and defining the content, place of work, time of its beginning and end, conditions for safe conduct, composition of the team and persons responsible for the safe conduct of work.

The order is of a one-time nature, its validity period is determined by the length of the executors’ working day. By order, work is carried out, as a rule, in electrical installations up to 1000 V.

Organizational measures to ensure the safety of work in electrical installations are:

Registration of work with an approval order, order or list of work performed in the order of current operation;

Permission to work is carried out after checking the preparation of the workplace. Preparation of the workplace is carried out by the work manufacturer with a permit issued by the operating personnel (dispatcher). In cases where the work foreman combines the duties of a permitter, he must prepare the workplace with one of the team members who has group III. Preparation of the workplace and admission of the team to work can only be carried out after receiving permission from the operational personnel or an authorized employee. Permission to allow the brigade to work can be given to the personnel preparing the workplace in person, by telephone, radio, by messenger or through the operational personnel of the intermediate substation;

Supervision during work (after permission to work). Supervision over the team's compliance with safety requirements rests with the work manager (supervisor). The observer is not allowed to combine supervision with the performance of any work. If temporary care is necessary, the work foreman (supervisor) is obliged to remove the team (by removing it from the switchgear and locking the entrance doors);

Technical electrical safety measures. Technical measures to prevent electrical injuries include:

· stress relief;

· electrical insulation of equipment;

· use of reduced voltage;

· use of protective grounding and grounding of electrical equipment;

· protective shutdown, protective blocking;

· use of protective equipment.

Electric Shock Protection

Basic electrical protective equipment is capable of long-term protection of personnel from electric shock when touching live parts.

In electrical installations up to 1000V, these include insulating rods, electrical clamps, dielectric gloves, tools with insulating handles, and voltage indicators. In electrical installations over 1000 V, insulating rods, electrical clamps, voltage indicators.

Additional electrical protective equipment is not able to withstand operating voltage for a long time and protect a person from electric shock at this voltage. They serve to enhance the protective effect of the main insulating agents with which they are used.

In electrical installations up to 1000V, this includes dielectric overshoes and mats, insulating stands and covers. For electrical installations over 1000 V - dielectric gloves, boots, mats and stands.

CONCLUSION

The purpose of this qualifying work is to study methods of laying and types of electrical wiring, installation, repair, maintenance, and prospects for modernization in the future.

The first step to complete this work was the selection and elaboration of regulatory and technical literature. Currently, various development companies are producing new technical products: connecting and end couplings, heat-shrinkable tubes, cabinets, control buttons, control and alarm relays, fuses, surge suppressors, and others. For example, to connect wire and cable cores, couplings with improved qualities are produced that allow for external protection and sealing, and the ability to cross wires during phasing.

Electric power industry is a leading branch of socialist industry, which largely determines modern scientific and technological progress. Without energy, enterprises and factories cannot exist, not a single branch of science or the national economy can develop.

The laying of electrical wiring is based on knowledge and compliance with safety regulations, the ability to choose the right brands of wires and cables, and knowledge of the sequence of work performed.

This work also addresses the issues of organizing an electrician’s workplace for the repair and maintenance of electrical equipment. The responsibilities of an electrician include installation, repair, and maintenance work. Thus, the place of work must comply with sanitary standards: temperature, lighting.

From the point of view of the scientific organization of labor, the workplace must comply with established psychophysiological, sanitary, hygienic and aesthetic standards, which contribute to attractiveness, preservation of health and performance, and, ultimately, increased labor productivity.

The goals and objectives set in the final qualifying work have been fulfilled.

Bibliography

1. Atabekov V.B. Repair of electrical equipment of industrial enterprises. - M., 2004

2.M., Sokolov B.A. Installation of electrical installations. - M., 2003.

3.Networks of industrial premises. – M., 2007. Ktitorov A.F.

4.Industrial training for electricians in lighting, lighting and power networks of electrical equipment. – M., 2006.

5. Mukoseev Yu.L. Rules for electrical installations. – M., 2006. Rules for technical operation of consumer electrical installations. – M., 2005.

6.Instructions for electrical safety and fire safety.

7. Catalogs and directories.

8. Internet network.

9.V.M. Nesterenko, A.M. Mysyanov Technology of electrical installation work. 2nd ed., erased. – M.,: Publishing Center “Academy”, 2005.

10.L.E. Trunkovsky. Maintenance of electrical equipment of industrial enterprises.

11.L.V. Zhuravleva. Electrical materials science. – M.: ProfObrIzdat, 2002.

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introduction

Electrical installation work is currently being carried out at a high level of engineering training, with the maximum transfer of this work from construction sites to the workshops of assembly and procurement sites and to the factories of electrical installation organizations.

Electrical installation, design and scientific research organizations, together with the electrical industry, are doing a lot of work on the manufacture of electrical equipment in large blocks and assemblies. Modern mechanisms, devices, tools, and small-scale mechanization equipment are being introduced into the practice of electrical installation and repair work.

Electrical installation work must be carried out in accordance with the requirements of “Building Norms and Rules” (SNiP); design and directive documentation; “Rules for Electrical Installation Devices” (PUE); safety regulations, labor protection; fire safety; norms for the consumption of materials, structures and products for capital construction; organization of work, rationing of labor.

Installation and maintenance of modern electrical equipment and electrical networks require deep knowledge of the physical fundamentals of electrical engineering, the designs of electrical machines, devices, and knowledge of materials. Modern technology is constantly being improved and changed, so a worker in any sector of the national economy needs, not limited to the knowledge acquired during the training process, to constantly replenish his professional knowledge.

Installation of electrical equipment must be able to be carried out quickly, efficiently, cheaply, and be able to properly organize production; know the purpose, principle of operation and conditions of use of the equipment; fixtures and instruments used during installation; know modern and promising installation methods; strictly follow safety precautions during electrical installation work.

An electrician for the operation of electrical equipment at stations, substations and power lines must know the conditions of technical operation of high-voltage installations, the procedure and rules for operational switching, as well as the processes for servicing electrical equipment and the technology for its repair.

Independent work to acquire new knowledge and skills is the right way to improve professional skills. A wide path of creative work and continued education opens up for a young worker.

Classification of electrical wiring

Electrical wiring is divided into open and hidden according to the method of execution. Open wiring is electrical wiring laid on the surface of walls, ceilings, trusses, machine frames, and hidden wiring is electrical wiring laid in the structural elements of buildings (walls, ceilings, floors, foundations, etc.). Open electrical wiring can be stationary, mobile and portable.

External electrical wiring is laid along the outer walls of buildings and structures, under canopies, as well as between buildings on supports (no more than four spans up to 25 m each) outside streets and roads. External electrical wiring can be open or hidden, have various design forms that determine the methods of its installation, taking into account environmental conditions, safety regulations, fire safety and other factors.

Open electrical wiring is carried out on insulating supports, directly on building foundations, trays, cables, and hidden wiring is carried out in metal and non-metallic pipes, under plaster, in closed channels of building structures, embedded in building structures during their manufacture, in blind boxes. Intrashop lighting networks with voltages up to 1000 V can have both open and hidden electrical wiring, but open pipeless wiring is preferable as it is less labor-intensive, more economical and meets the requirements of industrial installation (preliminary preparation and assembly of wiring components and parts on production lines in workshops of installation organizations). Since industrial buildings are constructed mainly from prefabricated reinforced concrete structures, to which fastening is difficult, electrical wiring is more often used that requires a smaller number of fastenings to building parts, for example, cable, in trays, etc.

Preliminary bench preparation of open electrical wiring, the presence of a large range of installation products and parts, which allows the assembly of large-sized units and entire lines from pre-prepared network elements, as well as the possibility of using a number of mechanisms and devices on the installation site, ensure a high degree of industrialization of the installation of open pipeless electrical networks in workshops of industrial enterprises.

Technology of installation and repair of open electrical wiring

Installation and repair of open electrical wiring, carried out with flat wires APPR, APPV, PPV, is carried out in a certain technological sequence.

First, they mark the installation locations of lamps, switches and sockets, electrical wiring lines, wire fastenings, i.e. points for driving nails, installing staples and places where wires pass through walls and ceilings, starting from a group panel with a gradual transition to individual rooms.

The installation locations of lamps on the ceiling are marked depending on their number. If one lamp is installed in the center of the room, then its location is determined by pulling two cords crosswise from opposite corners. The point of their intersection on the floor is marked with chalk, then this point is transferred with a plumb line from a stepladder to the ceiling. If you need to install two lamps in a room on the ceiling, then mark a middle line on the floor and divide it into four equal parts. The markings are transferred to the ceiling. The lamps are installed from the wall at a distance of 1/4 of the length of the room.

After determining the installation locations of the lamps on the wall and ceiling, use a cord to mark out the line of future electrical wiring. On the line, the points of attachment of the wire are marked, as well as the points of through holes for the passage of wires through walls and ceilings. Next, using the template, mark the installation locations of branch boxes, plug sockets and switches.

If holes were not left in advance in brick, concrete; on concrete and reinforced concrete foundations, they are performed using electrical, pneumatic or pyrotechnic tools (Fig. 1).

Wire passages through fireproof walls are made in rubber or polyvinyl chloride tubes, and through combustible walls - in sections of steel pipes, with insulating bushings on both ends. The tube in the hole is sealed with cement mortar. The insulating tube should protrude 5-10 mm from the sleeve.

Flat wires are supplied to the installation area in coils. Before laying, they are unwound, cut into lengths and straightened. To do this, one end of the wire is secured, and the wire itself is pulled through a special straightening device or a mitten worn on the hand. The wire should be pulled through very carefully so as not to damage the sheath. Straightening of flat wires can only be done at a temperature not lower than -15 °C.

Figure 1 – Tools, mechanisms and devices for punching work:

a- bolt; b – furrow cutter; c – burik;

g – electric jointing hammer with a set of working tools

For a three-core wire, the jumper between the second and third cores is also cut (Fig. 2, a). The wire is laid, starting from the box, along the entire straight section to the point where the route turns.

In this case, the wire at the other end is temporarily secured, carefully straightened, laid along the entire length of the section and finally secured along the entire length of the route.

When laying flat wires with a dividing partition (except for APPR wires) on combustible bases, asbestos with a thickness of at least 3 mm is laid under them along the entire length with a protrusion from the edge of the wire of at least 10 mm.

Flat wires with a dividing base are secured with nails, protecting the wires from damage. Plastic, rubber or ebonite washers should be placed under nail heads in damp, unheated rooms. Wires without a dividing base are fastened with staples using dowels or nails, with a distance between fastening points of no more than 400 mm.

For flat wires with a dividing base, when bending them on an edge (when the route is turned 90°), the base is cut out at the point of bending at a length of 40-60 mm (Fig. 2, b).

Figure 2 – Operations for preparing a flat wire before installation:

a - accession; b – bending on an edge in the plane of the wall

Figure 3 – Universal pliers KU-1 and performed

with their help installation operations:

a – cutting the wire; b-d – removal of the jumper; d – removal of insulation;

e - making rings

The next electrical installation operations are the connection and branching of flat wires in branch boxes.

These operations are performed by welding, crimping or soldering, followed by insulation with polyethylene caps or insulating tape.

The wires in the circuits of plug sockets are connected directly to the contacts of the sockets.

Laying unprotected wires on insulators is used in production and warehouse premises along walls, ceilings and the lower belt of trusses in dry, damp, damp and especially damp rooms, as well as outside (Fig. 4, a-c).

Figure 4 – Examples of electrical wiring on insulators:

a – by farms; b – along the walls; c - holders

Parts and structures for fastening insulators and wires are manufactured in factories. Each structure is a metal base with insulators on which wires are secured with special holders. Supporting metal structures (traverses) are made for fastening to trusses and walls by welding, clamps for two-, three- and four-wire lines.

As a rule, when installing electrical wiring on insulators, marking the electrical wiring is done in the same way as when wiring with flat wires.

Insulators are installed with the “skirt” down for all methods of their fastening. Next, end insulators are installed at passages through walls and when wires pass from one adjacent wall to another. Hooks and anchors with insulators are secured with putty. Wire passages through walls and ceilings are made in insulating tubes terminated with bushings. One wire is placed in each tube.

At the installation site or at the power plant, wires are prepared and laid along prepared routes, and the minimum distance from the wires to the surface of walls and ceilings must be at least 10 mm.

Protect wire runs from mechanical damage at a height of at least 1.5 m from the floor or service area by covering them with angle steel or laying them in pipes.

The wires are secured on pin insulators with galvanized wire, and on trolley insulators with intermediate and end holders.

Electrical wiring made with insulated and protected wires and cables suspended from a steel cable with a diameter of 3-8 mm or special AVT wires; AVTU; ABTV; AVTVU, which have their own supporting galvanized cable between three or four twisted cores, are called cable wiring.

In cable wiring, elements manufactured in factories are mainly used. The cables are attached to the end walls using through anchors or anchors attached to through pins, bolts or dowels (Fig. 5).

Figure 5 – Installation of cable wiring elements:

a – anchor with tension sleeve; b – cable termination using thimble and die clamps; c – supporting cable; g – tension through bolt with hook; d - tension through bolt with ring; e – laying of insulated wires on cable hangers with wire plugs on nut-type insulators; g – grounding the cable of the ART wires using the free end of the loop

A loop is made at the end of the cable and a cable clamp and couplings are installed to adjust the tension of the cable. When wiring with cable wires, special branch boxes are used, which are simultaneously used for hanging the cable wire and lamps (Fig. 6).

Inside the box there is a device for fastening the cable. Branches are made without cutting the wire using clamps in a plastic casing. Cable wiring units are installed at factories or in oil extraction plants on production lines and delivered to the work site in containers.

Description of work

Modern mechanisms, devices, tools, and small-scale mechanization equipment are being introduced into the practice of electrical installation and repair work.
Electrical installation work must be carried out in accordance with the requirements of “Building Norms and Rules” (SNiP); design and directive documentation; “Rules for Electrical Installation Devices” (PUE); safety regulations, labor protection; fire safety; norms for the consumption of materials, structures and products for capital construction; organization of work, rationing of labor.

Installation of open electrical wiring, carried out with flat wires APPR, APPV, PPV, is carried out in a certain technological sequence. First, they mark the installation locations of lamps, switches and sockets, electrical wiring lines, wire fastenings, i.e. points for driving nails, installing staples and places where wires pass through walls and ceilings, starting from a group panel with a gradual transition to individual rooms.
The installation locations of lamps on the ceiling are marked depending on their number. If one lamp is installed in the center of the room, then its location is determined by pulling two cords crosswise from opposite corners. The point of their intersection on the floor is marked with chalk, then this point is transferred with a plumb line from a stepladder to the ceiling. If you need to install two lamps in a room on the ceiling, then mark a middle line on the floor and divide it into four equal parts. The markings are transferred to the ceiling. The lamps are installed from the wall at a distance of 1/4 of the length of the room.
After determining the installation locations of the lamps on the wall and ceiling, a line of future electrical wiring is cut off using a cord. On the line, the points of attachment of the wire are marked, as well as the points of through holes for the passage of wires through walls and ceilings. Next, using the template, mark the installation locations of branch boxes, plug sockets and switches.

A - bolt; b - furrow cutter; c - burik; g - electric jointing hammer with a set of working tools

If holes were not left in advance in brick, concrete and reinforced concrete foundations, they are made using electrical, pneumatic or pyrotechnic tools (Fig. 4.2). Wire passages through fireproof walls are made in rubber or polyvinyl chloride tubes, and through combustible walls - in sections of steel pipes, with insulating bushings on both ends. The tube in the hole is sealed with cement mortar. The insulating tube should protrude from the sleeve by 5-10 mm.
Flat wires are supplied to the installation area in coils. Before laying, they are unwound, cut into lengths and straightened. To do this, one end of the wire is secured, and the wire itself is pulled through a special straightening device or a mitten worn on the hand. The wire should be pulled through very carefully so as not to damage the sheath. Straightening of flat wires can only be done at a temperature not lower than - 15° C.

Operations for preparing a flat wire before installation: a - connection; b - bending on an edge in the plane of the wall

After straightening and cutting the wires, they are wound into coils. The laying of wires begins with the branch box closest to the group panel. A dividing base is cut out at the ends of a 75 mm long wire. For a three-core wire, the jumper between the second and third cores is also cut (Fig. a). The wire is laid, starting from the box, along the entire straight section to the point where the route turns. In this case, the wire at the other end is temporarily secured, carefully straightened, laid along the entire length of the section and finally secured along the entire length of the route. When laying flat wires with a dividing partition (except for APPR wires) on combustible bases, asbestos with a thickness of at least 3 mm is laid under them along the entire length with a protrusion from the edge of the wire of at least 10 mm.
Flat wires with a dividing base are secured with nails, protecting the wires from damage. Plastic, rubber or ebonite washers should be placed under nail heads in damp, unheated rooms. Wires without a dividing base are fastened with staples using dowels or nails, with a distance between fastening points of no more than 400 mm. For flat wires with a dividing base, when bending them on an edge (when the route is turned 90°), the base is cut out at the point of bending at a length of 40-60 mm.

Universal pliers KU-1 and installation operations performed with their help:
a - cutting the wire; b - d - removal of the jumper; d - removal of insulation; e - manufacturing
rings

When cutting flat wires, KU-1 or MB-241 pliers are often used, with which you can cut the film, bite it out, remove insulation from the ends of the wires, strip the wires and bend the rings at the ends of the wires to connect them to the contact screw.
The next electrical installation operations are the connection and branching of flat wires in branch boxes. These operations are performed by welding, crimping or soldering, followed by insulation with polyethylene caps or insulating tape. The wires in the circuits of plug sockets are connected directly to the contacts of the sockets.
Laying unprotected wires on insulators is used in production and warehouse premises along walls, ceilings and the lower belt of trusses in dry, damp, damp and especially damp rooms, as well as outside.
Parts and structures for fastening insulators and wires are manufactured in factories. Each structure is a metal base with insulators on which wires are secured with special holders. Supporting metal structures (traverses) are made for fastening to trusses and walls by welding, clamps for two-, three- and four-wire lines.

Examples of electrical wiring on insulators: a - on trusses; b- on the walls; c - holders

As a rule, when installing electrical wiring on insulators, marking the electrical wiring is done in the same way as when wiring with flat wires.
Insulators are installed with the “skirt” down for all methods of their fastening. Next, end insulators are installed at passages through walls and when wires pass from one adjacent wall to another. Hooks and anchors with insulators are secured with putty. Wire passages through walls and ceilings are made in insulating tubes terminated with bushings. One wire is placed in each tube.
At the installation site or at the power plant, wires are prepared and laid along prepared routes, and the minimum distance from the wires to the surface of walls and ceilings must be at least 10 mm.
Protect wire runs from mechanical damage at a height of at least 1.5 m from the floor or service area by covering them with angle steel or laying them in pipes.
The wires are secured on pin insulators with galvanized wire, and on trolleybus insulators with intermediate and end holders.
Electrical wiring made with insulated and protected wires and cables suspended from a steel cable with a diameter of 3-8 mm or special AVT wires; AVTU; ABTV; AVTVU, which have their own supporting galvanized cable between three or four twisted cores, are called cable wiring.

a - anchor with tension sleeve; b - end seal of the cable using a thimble and die clamps; c - supporting cable; g - tension through bolt with hook; d - tension through bolt with ring; e - laying of insulated wires on cable hangers with wire plugs on nut-type insulators; g - grounding the APT wire cable using the free end of the loop

This type of electrical wiring is best for industrial installation. It is used in any environmental conditions, including hazardous areas of certain classes. When spans between cable hangers are 6 and 12 m, the cable sag should be 100-150 and 200-250 mm, respectively.
In cable wiring, elements manufactured in factories are mainly used. The cables are attached to the end walls using through anchors or anchors attached to through pins, bolts or dowels.
A loop is made at the end of the cable and a cable clamp and couplings are installed to adjust the tension of the cable. When wiring with cable wires, special branch boxes are used, which are simultaneously used for hanging the cable wire and lamps. Inside the box there is a device for fastening the cable. Branches are made without cutting the wire using clamps in a plastic casing. Cable wiring units are prepared at factories or at oil extraction plants on production lines and delivered to the installation site in containers.

Cable branch box with hook for hanging lamps

Installation of electrical wiring with light cables with rubber and plastic insulation:
a - methods of cable fastening; b - device for turning at an angle of 90°; c - branching device with several cables laid in parallel

To install cable wiring, first mark the places of fastening of anchor and intermediate structures along the room along the line of location of lamps or power receivers, maintaining the distances between pendants, branch boxes and lamps according to the design and sketches of measurements at the installation site. Next, anchor and tension devices are attached to the main building elements (walls, trusses, etc.), hangers for intermediate fastenings are installed and they are attached to the lower chords of the trusses, columns, floors, in the cracks between the corners of the trusses or floor slabs. Then sections of the supporting cable, strings and guys are prepared, they are terminated with loops using sleeves and clips, the end fastening is assembled and measured sections of wires are prepared for the electrical wiring lines and the supply line (according to drawings or measurement sketches). After this, the wires are inserted into the boxes, the ends of the wires are connected in boxes or clamps, they are attached to the cable (for unprotected wires) with strips after 0.3-0.35 m, with perforated polyvinyl chloride tape after 0.5 m, with pendants after 1.5 m with plastic clips for two or four wires and clips for hanging lamps.
When using protected wires, fastening with strips is carried out every 0.5 m. The strips are soft spacers and should protrude 1.5-2 mm on both sides of the cable. Next, the wires are called and labeled. If special wires are used for cable wiring, then input and branching are carried out using compressions U245 and U246 without cutting the phase wires.
To lay the prepared lines, the wires are unwound on the floor using special crosses and raised to a height of 1.3-1.5 m for straightening and hanging the lamps. Next, the wires are raised to the design height and one end of the cable is secured to the anchor structure. Connect the line with previously installed intermediate hangers and guy wires. Adjust the sag and put the cable on the opposite anchor device. In places where exposed sections of the cable and the anchor device come into contact, they are lubricated with Vaseline. The cable at the end of the line is grounded at two points by connecting copper jumpers with a cross section of 2.5 mm 2 to the neutral wire or bus connected to the ground loop. The support cable cannot be used as a grounding conductor. Next, use a megohmmeter for voltages up to 1000 V to measure the insulation resistance of the electrical wiring. It must be at least 0.5 MOhm.
Electrical wiring with unarmored protected wires and cables with a cross-section of up to 16 mm 2 with rubber and plastic insulation is laid directly on the surface of the walls. Such electrical wiring is secured with staples, buckles (Fig. 4.8) or on strips, tapes and strings (Fig. 4.9), which sharply reduces the labor intensity of hole-punching work.
Assembly perforated strips and tapes with a width of 16 and a thickness of 0.8 mm; cold- or hot-rolled tape with a width of 20-30 and a thickness of 1-1.5 mm are used as load-bearing structures. Tapes and strips are attached directly to the base with a distance between the attachment points of 0.8-1 m, and from the end of the strip - no more than 70 mm. Galvanized wire with a diameter of 3-4 mm, stretched close to the base and secured at the ends with tension devices, is used as a supporting string.
Protected wires APRF (PRF, PRFl) are straightened on a workbench or manually.

Laying cables and wires along the wall with fastening to the strings:
a - suspension U954; b - U957 suspension; c - Loskutov strip; g - tape K226; d- strip with PI buckle; e, i - PL strip with a buckle; g- strip 20 x 1 with a “mustache”;
h, j - mounting strip K-200
Wires and cables are secured with metal or plastic bands at a distance of 10-15 mm from the places where the route bends and 100 mm from their entry into the branch boxes. The distance between fastening points is 500 mm. Bearing strips, tapes and strings are grounded in the same way as cable wiring. The metal sheaths of the APRF, PRF, PRFl wires are grounded at the supply panels or points with a flexible copper jumper soldered to the metal sheath of the cable or wire.

Construction and finishing. Equipment. Wallpaper. Coloring. Facade

Technology of installation and repair of electrical wiring. Electrical wiring installation technology Topic: open electrical wiring installation technology

Installation of tubular wires

BIG LENINGRAD LIBRARY - ABSTRACTS -

Electrical wiring installation technology

Installation of tubular wires

BIG LENINGRAD LIBRARY - ABSTRACTS -

Electrical wiring installation technology

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