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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Installation of open wiring. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Electric installation work In production open laying wires and cables along walls, partitions and ceilings, for aesthetic reasons, one should adhere to the architectural lines of the premises - cornices, lines of artistic processing, protruding corners, etc. So, in rooms pasted over with wallpaper, it is recommended to carry out the upper horizontal wiring above the wallpaper. Wire routes with hidden laying should be easily determined during the operation of the wiring. In order to exclude the possibility of accidental damage to the wiring during the installation of wall lamps, clocks, sconces, etc., the choice of the route of hidden laying of wires must be made according to the following rules: 1) horizontal laying along the walls should be carried out parallel to the lines of intersection of the walls with the ceiling at a distance of 100-200 mm from the cornice or beam. Mains of socket outlets are recommended to be laid along a horizontal line connecting socket outlets; 2) descents and ascents to switches, sockets and lamps are carried out vertically at a distance of up to 100 mm parallel to the lines of door and window openings or corners of the room; 3) hidden laying of wires on ceilings (in plaster, cracks and voids of slabs or under a floor slab) should be carried out along the shortest distance between the most convenient transition point to the ceiling from the junction box to the fixtures. The marking of the routes of hidden wiring, recessed into the grooves of walls and ceilings, can be done in the shortest direction from the inputs to the electrical equipment and lamps. In rooms without increased danger, the height of the reinforcement suspension must be at least 2 m from the floor to the cartridge. If the ceilings are low and this requirement cannot be met, luminaires are used in which access to the lamps is closed. It is allowed to lay flat wires in light-resistant insulation (APPV, APPR), protected wires in a metal sheath (APRF) and cables ANRG, AVRG, AVVG, APVG on fireproof and non-combustible substrates (plaster, brick, concrete). Only APPR, APRF wires and cables with a sheath made of slow-burning materials - ANRG, AVRG, AVVG can be laid directly on combustible substrates (wood, chipboard, hardboard). Other wires and cables must be laid on a separating layer of non-combustible insulating material - on a strip of sheet asbestos with a thickness of at least 3 mm or a layer of plaster with a thickness of at least 10 mm. The separating layer must protrude from under the wire by at least 10 mm on each side. Wires are laid along the line of cornices and the ceiling at a distance of 100-150 mm from them, fixed at regular intervals at a distance of up to 400 mm from each other with metal strips or nails. Under the metal strips to protect the insulation of the wires, pads of insulating cardboard are placed, which should protrude 2 mm on both sides of the strip. Metal strips are bent in the form of brackets and nailed or fixed in a lock. In damp and damp rooms, washers made of fiber, polyethylene or polyvinyl chloride are placed under the nail heads.
a - steel bracket; b - plastic bracket; in - a plastic strip with a buckle; g - plastic jagged strip With a parallel arrangement of wires, the distance between them should be 3-5 mm. At the intersection of the wires, 2-3 layers of polyvinyl chloride insulation are applied to the lower wire. At the turn of the wire route in one plane along one wall, the connecting film at the bend is cut out at a length of 60 mm, and the inner core is bent to the center of the corner. When turning the route to another wall or when moving from the ceiling to the wall, the wire is bent without cutting the film, and the bending radius is taken at least 20 mm. In order to connect wire cores to screw or wedge terminals of apparatus and electrical installations, the insulation is removed from the ends of the wires. In junction boxes, wires are connected by welding, soldering, crimping or screw clamps. In fire and explosive, especially damp rooms, as well as in attics, electrical wiring is installed in steel pipes, at the ends of which threads are knurled. The neutral wire is laid in the pipe along with the phase wires. A package of several pipes is fixed using special support structures and brackets; single pipes are fixed to the surfaces of building structures with brackets, overlays or clamps. In order to prevent moisture from condensing vapors from accumulating inside the pipes, pipe routes are mounted with a certain slope towards broaching cabinets and boxes. The length of the route between the broaching boxes depends on the number of bends and should be: with one bend - up to 50 m, with two - up to 40 m, with three or more - up to 20 m. Bending radii for open laying should be at least 6 diameters, with hidden - no more than 10 diameters. The standard dimensions of bending radii for turning the route at angles of 90°, 105°, 120°, 135°, 150° are 160, 200, 250, 400, 800 mm, respectively. In order to protect the electrical wiring from the effects of an aggressive environment, fire or explosion, the pipeline must have tight connections of all links. The distances between the attachment points - brackets, overlays, fasteners - depend on the diameter of the pipes and are: for small diameters - 2,5 m, for diameters of 50 mm and more - 4 m. Pipelines are attached to the apparatus by welding, threaded connections or special nuts. Welding work on the laying of pipes is carried out before tightening the wires into them. Light switches set:
The installation of socket outlets is planned in places convenient for use, and depending on the interior design. They must be located at a distance of at least 0,5 m from grounded fittings (pipelines for heating, water, gas, etc.). In kitchens, this distance is not standardized. Requirements for the installation of socket outlets: 1) installation height in rooms and kitchens is not standardized; 2) the installation height of socket outlets with a grounding contact intended for connection is not standardized air conditioners and electrical appliances that require grounding; 3) above-plinth type sockets are installed at a height of 0,3 m from the floor; 4) plug sockets should be installed for a current of 6 A based on: in living rooms - one for every full and incomplete 10 m2 of living space, in kitchens - two, regardless of the area of \uXNUMXb\uXNUMXbthe room. Open laying of unprotected insulated wires on rollers and insulators is allowed at a height of at least 2 m. normalized. Open electrical wiring indoors in places where mechanical damage is possible must be additionally protected. When laying two or more flat wires in parallel with open or hidden wiring, they must be laid flat on the wall (ceiling) next to each other with a gap of 3-5 mm. Lighting switches for kitchens, bathrooms, toilets, etc. are placed outside these rooms, and lamps are placed on the wall adjacent to the corridor. As a general rule, toilets and bathrooms should use hidden wiring, wires should be laid in PVC or other insulating tubes. It is not allowed to use protected wires in a metal sheath and lay them in steel pipes. The actual installation work begins with marking the installation sites of the apartment panel with an electric meter, sockets, lamps and switches, since the location of these elements determines the beginning and direction of the routes. After that, mark the places for installing junction boxes, avoiding obstacles, punching holes, passing through walls, partitions and ceilings, crossing wires and cables between themselves and with various pipelines, etc. To attach the wire to the surface of the wall or ceiling, use pieces of steel tape measuring 0,5x10x80 mm or the same strips of tinned sheet. Strips are nailed to wooden surfaces. If the wall is made of brick or concrete, then the strips are fixed with screws, screwing them into expansion dowels made of polyethylene, embedded in nests about 40 mm deep, which require a drill or punch with a carbide tip. It is not recommended to use wooden plugs for fixing screws in brick and concrete walls, as they, either swelling or drying out in conditions of variable humidity, decrease in size and cease to stick to the wall. Instead of a spacer dowel, you can use an insulating PVC tube. It is cut along the generatrix and the resulting tape is rolled into a tight roll of such a diameter that it fits into the nest as tightly as possible. When screwing in the screw, the roll will increase in diameter and will be securely fixed in the socket along with the screw. The screw in the socket can also be fixed with alabaster, having previously screwed a wire in the form of a spiral onto its thread. After the alabaster hardens, the wire forms a metal-shaped thread in the thickness of the wall, which allows you to screw in and out the screw repeatedly. In nests with a diameter of 10-12 mm and a depth of about 40 mm, metal strips 0,5x10x150 mm in size folded in half can be fixed with alabaster. The strips are placed at a distance of 400 mm from each other along the wire laying line. The strips closest to the switch, socket or junction box must be 50 mm away from them. A 15x40 mm rectangle of electric cardboard - pressboard is laid on each strip, and a wire is placed on top of it. The cardboard spacer protects the wire insulation from possible damage by the edge of the strip. Having covered the wire with a gasket and clasping it with a strip, its ends are connected "in a lock" or fastened with a flat steel buckle. Flat wires in rooms without increased risk of electric shock may be fixed to wooden walls and ceilings with nails 1,4x20 mm with a head diameter of not more than 3 mm. Nails are hammered every 200-300 mm strictly into the middle of the dividing strip of the wire using a hammer weighing up to 0,2 kg and a mandrel, which excludes damage to the core insulation when driving nails. In unheated wet rooms, it is necessary to put washers made of fiber, polyethylene, ebonite or rubber 1,5-1 mm thick under the caps. With open wiring, sockets and switches are installed on round or rectangular sockets made of wood, chipboard or plastic, fixed to the wall with screws. Before laying the wire, it is necessary to smooth it out by stretching it through a rag clutched in your hand. At switches, sockets, in junction boxes, a wire reserve of about 100 mm is left for making connections, branches and connections to equipment terminals. Before connecting a flat wire to a socket, switch or other device, cut a separate strip 20 mm long from its end, and then release the ends of the separated wires from insulation and arrange them with a "ring" or "pin" to make the connection. When changing the direction of the laying line, the flat wire is bent by turning it "on edge" or by cutting out a dividing strip between the cores and bending one of the cores into the corner. Bending the wire core inside the corner is often difficult even for professional electricians, and they prefer to bend the wire "on edge", which is easier, but less aesthetically pleasing. Meanwhile, the simplest technique is known that allows you to successfully bend the wire strand even without the skill of its implementation. In the place of the required bend, the wire is folded in half, a dividing strip is cut by 5 mm and one of the cores is bent to the side at an angle of 90 °. After that, it remains only to straighten the double-folded wire. When laying trunk line wires, do not cut them in junction boxes. In each of the boxes, you need to leave a supply of wire in the form of a loop about 200 mm long and continue laying the wires along the wall. Flat wires must not be used to charge pendant lights and lamp sockets. Flat wires are connected to copper stranded wires. APRF cables and wire with a protective metal sheath are attached to walls and ceilings using metal brackets with one or two legs. The fixing points of the single-claw brackets on the horizontal sections of the wiring along the walls should be located below the cable. To protect the cable from damage, a pad of electrical cardboard is placed between it and the bracket. The distance between adjacent brackets should not exceed 500 mm on horizontal, 700 mm on vertical sections of wiring. The brackets closest to the switches, sockets and junction boxes must be 50 mm away from them. Pieces of wire on walls and ceilings are temporarily fixed with brackets at the ends, at turns and after 1,5 m on straight sections of wiring. After making connections, branches and connections in accordance with the wiring diagram, the cable is again aligned and finally fixed with brackets. The laying of the APRF wire has features: on the vertical sections of the wiring, the seam of its shell - the fold - must be adjacent to the wall, on the horizontal ones it is turned down to prevent water from flowing into the shell. When bending the wire, the fold should be located inside the corner. If it is on the side during bending, it will inevitably disperse and the wire will be damaged. Author: Bannikov E.A.
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