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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Types of electrical wiring. Characteristics and wiring diagrams. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Electric installation work According to the safety requirements, electrical installations are divided into 2 groups: voltage up to 1000 V и above 1000 V. The elements of electrical installations are input devices from the 0,4 kV power line to the source of consumption, external and internal electrical wiring, as well as electrical energy receivers, i.e. heating, lighting, household appliances, etc. All electrical installations, regardless of their location, are constructed, installed and operated in accordance with the Rules for the Installation of Electrical Installations (PUE), Building Codes and Rules (SNiP), Safety Rules (PTB), Rules for the Use of Electric and Thermal Energy, Fire Safety Rules, as well as the instructions of factories - manufacturers of household and household appliances. In electrical literature, special terms, concepts and definitions are used. To indicate the obligatory fulfillment of the requirements of the PUE, the words "should", "should", "necessary" and their derivatives are used. group network - a network that feeds lamps and sockets. Double insulation of the electrical receiver - a combination of working and protective (additional) insulation, in which the accessible parts of the electrical receiver do not acquire dangerous voltage if only the working or only protective (additional) insulation is damaged. Double insulation of wires and cables - in everyday life, the wrong name for protected wires and cables that have two layers of coatings. One layer is the insulation of current-carrying conductors, the second is a sheath that serves to protect against external influences and for sealing and is not insulation. Allowed - this decision is applied as an exception as a forced one (due to natural conditions, limited resources of the necessary equipment, materials, etc.). Grounding - intentional electrical connection of a part of an electrical installation with a grounding device. Zeroing in electrical installations with voltage up to 1 kV - deliberate connection of parts of an electrical installation that are not normally energized with a dead-earthed neutral of a generator or transformer in three-phase current networks. Grounding device - a set of grounding conductors and grounding conductors. Earth fault - accidental connection of energized parts of an electrical installation with structural parts that are not isolated from earth, or directly with earth. Short circuit to the body - accidental connection of energized parts of an electrical installation with their structural parts that are not normally energized. Insulator - an electrical device for isolating parts of electrical equipment under different electrical potentials and preventing open circuits to the ground, housing, structure. As a rule - this requirement is predominant, and deviation from it must be justified. Qualified service personnel - specially trained persons who have passed the knowledge test to the extent required for this work, and who have a qualified safety team, provided for by the Safety Rules for the operation of electrical installations. No more - the values of the quantities are the largest. no less - the values of the quantities are the smallest. Consumer of electrical energy - an enterprise, organization, institution, object, site, apartment, etc., connected to electrical networks and using energy using existing receivers. Receiver of electrical energy (electric receiver) - an installation or device designed to receive and use electrical energy. Wiring products - the general name of sockets, switches, switches, sockets, plugs, fuses, etc. Wiring - a set of wires and cables with their associated fasteners, supporting protective structures and parts installed in accordance with the Electrical Installation Rules. Depending on the purpose and execution, all electrical installations are divided into several groups. Those that drive pumps and other process equipment are called power, and those intended for lighting, connecting household electrical appliances - lighting. According to the degree of protection from the external environment, they are divided into open (outdoors) and closed (located in the room). Electrical installations are stationary and mobile. Houses (villas, cottages, country houses)t:
In houses and cottages, the owners and members of their families live permanently, and in garden plots, or dachas, they are most often seasonal. Subject to the specified conditions premises are classified according to the degree of flammability of building materials and structures, environmental conditions and the degree of electric shock to people. In accordance with fire safety requirements of SNiP building materials and structures according to the degree of flammability are divided into three groups: combustible, slow-burning and fireproof. К fireproof include all natural and artificial inorganic materials used in construction; metals; gypsum and gypsum-fiber boards with an organic matter content of up to 8% by weight; mineral wool boards on a synthetic, starch or bitumen binder with its content up to 6% by weight. К fire-retardant include materials consisting of non-combustible and combustible components, such as asphalt concrete; gypsum and concrete materials containing more than 8% by weight of organic aggregate; mineral wool boards on a bituminous binder with its content of 7-15%; clay-straw materials with a density of at least 900 kg/m; felt soaked in clay solution; wood subjected to deep impregnation with flame retardants; cement fiberboard; polymer materials. К combustible include all organic materials that do not meet the requirements for non-combustible or slow-burning materials. According to PUE rooms in which lighting and power electrical installations, various electrical appliances, electrically driven mechanisms, etc. are used, are divided into dry, damp, damp, especially damp, hot, dusty, rooms with a chemically active environment, fire and explosion hazard. Dry are called rooms in which the relative humidity does not exceed 60%. Normal dry rooms are called if there are no conditions "especially damp, hot, dusty". Wet - those in which the relative humidity of the air is more than 60%, but does not exceed 75%. Vapors or condensing moisture in them are released temporarily and in small quantities. К raw include rooms in which the air humidity for a long time exceeds 75%, especially damp - those where the relative humidity of the air is close to 100% (the ceiling, walls, floor and objects in the room are covered with moisture). Thus, garden houses and other premises in which people live temporarily and which are not permanently heated should be classified as "wet" or "damp". In the private sector, premises for the installation of electrical installations can be dry, wet, damp, especially damp and fire hazardous. In respect danger of electric shock to people premises, depending on the combination of certain environmental conditions (humidity, temperature, conductive floors, etc.), are divided into: 1) to premises without increased danger, in which there are no conditions that create an increased or special danger; 2) premises with increased danger, characterized by the presence in them of one or more conditions that create an increased danger: dampness or conductive dust, conductive floors (metal, earthen, reinforced concrete, brick, etc.), high temperature, the possibility of simultaneous contact of a person with having a connection to the ground metal structures of buildings, devices and mechanisms on the one hand and to the metal cases of electrical equipment - on the other; 3) especially dangerous premises - are characterized by the presence of one of the following conditions that create a special danger: especially damp premises, simultaneously two or more conditions of increased danger. Wiring diagrams on the plans of cottages and garden houses, they are carried out for each floor on a scale of 1:100 or 1:200, external electrical wiring on the territory - on a scale of 1:500 or 1:1000. Lamps, switches, sockets, electrical wiring, protection devices in the drawings of plans are indicated by conventional signs. Electrical wiring on the plans are applied in a single-line design. Near the lines indicate the brand and cross section of the wire or cable, conditionally indicate the method of laying. For example, T - in metal pipes, P - in plastic pipes, Mp - in flexible metal hoses, I - on insulators, P - on rollers, Ts - on cables. The number of wires, cores in the wire and their cross-sectional area are shown as a product. The designation PV 2 (1x2,5) is deciphered as follows: two single-core wires of the PV brand with a cross section of a current-carrying core of 2,5 mm 2. The number of wires in the amount of more than two is also indicated by serifs at an angle of 45 ° to the line. У Fixtures a fraction indicates the power of the lamp (W) in the numerator, and the height of the suspension above the floor (m) in the denominator. The receiver of electrical energy is also denoted by a fraction: the numerator indicates the number according to the plan, and the denominator indicates the rated power (kW). As an example, in fig. 1 shows a diagram of a residential building and a block of outbuildings.
Wiring is divided into open and hidden. exposed wiring it is laid on the surface of walls, ceilings, on strings, cables, rollers, insulators, in pipes, boxes, flexible metal sleeves, on trays, in electrical skirting boards and platbands. Can be stationary, mobile or portable. Concealed wiring is laid inside the structural elements of buildings and structures: in walls, floors, foundations, ceilings, on ceilings in floor preparation, under a removable floor, etc., as well as in pipes, flexible metal hoses, ducts, closed channels and voids in building structures, in plastered furrows, under plaster, it can be embedded in building structures during their manufacture. In order to reduce the installation time of electrical networks, trunk, distribution, trolley and lighting busbars are used. Busbar - complete electrical network. It consists of separate sections connected by welding, bolted or plug-in connections, as well as casings and materials for insulating joints and structures for attaching brackets, racks, suspensions. Busbar sections are made straight and shaped for assembling an electrical network of any configuration. Open wiring is laid in boxes or on trays. In this case, the consumption of steel pipes is reduced, labor productivity is almost doubled, and the aesthetic appearance is improved. Cables with a plastic sheath are laid in boxes close to each other in one or more layers, as well as in bundles. The sum of the cross-sectional areas of cables laid in one box, including control and reserve ones, should not exceed 40% of the inner cross-section of the box. Cables with a cross section of up to 16 mm are laid on the trays (cables of large cross sections can also be laid if their routes coincide with the routes of cables with a cross section of up to 16 mm) in one layer with a clear distance of about 5 mm and bundles in one layer (row) with distances between beams in the light of about 20 mm or multi-layered. Cable bundles are fastened with bandages at a distance of not more than 1,5 m between them on horizontal straight sections of the route. When laying vertically, the distance between the fasteners should be no more than 1 m. Cables are fixed to the trays at a distance of no more than 0,5 m before and after they are turned or branched. Depending on the methods of laying cables in boxes or trays (multilayer, bundles, etc.), coefficients are introduced to reduce the electrical load on these cables. Cable wiring they call electrical wiring made with special wires with a steel carrier cable built into them, as well as wiring made with installation insulated wires or cables, freely suspended or rigidly fixed on separate steel carrier cables. Special boxes used when branching on cable wires, which provide for a supply of cable and wires necessary to connect the outgoing line. Tension couplers, anchors, clamps etc. are used for the installation of cable wiring. Hidden electrical wiring is used in large-panel residential buildings when installed in embedded plastic pipes, boxes and embedded elements that are installed in building structures at factories. Packages of wires are pre-prepared on the technological lines of electrical assembly workshops; blanks are delivered in containers to objects. There, ready-made wire packages are pulled into pipes before finishing work is completed. Then, sockets and switches are installed in the embedded elements. One of the main electrical devices - wiring. The installation for artificial lighting includes light sources, lighting fixtures, ballasts, electrical wiring and switchgear with protection and control devices. lighting fittings called a device that provides the installation of a light source, its protection from external influences, redistribution of the luminous flux and screening of excess brightness. The lighting fittings consist of a housing, a lamp holder (cartridge), an optical system (reflector, diffuser), suspension and wires for connection to the electrical wiring. Lighting fittings with a lamp are called lamp. Fixtures are installed directly on the building foundations of structures or on brackets, cables, hooks, studs, etc. Of the fixtures, blocks are mounted, light lines installed on busbars, boxes, special perforated profiles. Connection to the mains of branch wires is carried out by crimping, welding, squeezing, etc. Author: Bannikov E.A.
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