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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Installation of electrical wiring with flat wires. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Electric installation work Wires of the brands APPV, PPV, APPVS, APPR and the like are allowed to be laid openly and hidden in dry, damp and damp rooms of a country (garden) house and in outbuildings. APPV, 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, pasted over with wallpaper). It is allowed to lay wires with PVC insulation on wooden and other combustible structures with non-combustible materials lining under them, for example, asbestos with a thickness of at least 3 mm, protruding from each side of the wire by at least 10 mm. The insulation of flat wires is made of a material that softens and melts at a temperature of 150190 ° C, and the current-carrying cores of flat wires are at a close distance from each other, so if the insulation melts when heated, a short circuit may occur. In addition, the insulation of flat wires is not protected from mechanical damage, and the presence of hidden damage to the insulation during operation can lead to an accident. For the above reasons, it is not allowed to use flat wires for open laying in fire hazardous rooms, especially damp rooms and in attics, and for hidden laying in especially damp rooms. Flat wires are not allowed to be used for charging lighting fixtures and hanging lampholders on them. With hidden electrical wiring, it is prohibited to embed wires of all brands in 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, passing through walls, etc. Editing flat wires is best done this way: clamp one end in a vice or secure it in another way, and then stretch the wire through a cloth or glove. When straightening single-core wires with PVC insulation (PV, APV, etc.), it is not recommended to pull them with great effort, since the insulation may be shifted. The laying of wires is carried out in sections: apartment shield - junction box - socket; junction box - lamp, etc. All wire connections are made only in junction boxes, the connection of wires to each other outside the boxes is not allowed. The wire is cut into pieces equal to the length of individual sections. At the end of the cores, a separating base (if any) is cut out with pliers, 80-100 mm long (a jumper between the second and third is allowed for a three-core wire). The wire is laid with light tension along the entire length of the straight section from the box to the turn of the track. When turning the wire, the separation base is cut out to give the corner the correct shape. After laying, the wire is temporarily fixed at the other end of the section, further straightened, and then finally fixed. When conducting the wiring, it must be possible to freely make wire connections in junction boxes, boxes for switches and sockets. Such a need arises when repairing or replacing switches, sockets, lamps. Therefore, the ends of the wire with separate cores are inserted into the boxes with a margin of 50-70 mm, after which the wire is fixed at the box. When laying in parallel, the wires should have a gap of 3-5 mm. If necessary, asbestos gaskets are fixed before the installation of wires, hammering nails into them every 200-500 mm in a checkerboard pattern.
With open laying, flat wires are fastened with nails, metal and plastic staples, clamps, strips, tapes, screws, dowels, or glued with special glue. Nails with a diameter of 1,4-1,8 mm and a length of 20-25 mm with a cap of up to 3 mm are hammered at a distance of 200-300 mm from each other along the midline of the film between the cores of the wire with a light hammer, using a mandrel or some other device, protecting the wire from damage. In damp, unheated rooms, it is recommended to place fiber, rubber or similar washers under the nail heads. Staples made of plastic, rubber, etc. are fixed at a distance of no more than 400 mm from each other. For fastening flat wires, polyethylene staples of the U641, U642 type, etc. are used. In the absence of special polyethylene staples, flat wires can be fastened using metal staples, previously fixed on the asbestos layer, if the base is combustible. Metal strips 10 mm wide and 0,3-0,5 mm thick are cut from a thin steel sheet with an anti-corrosion coating. Under the bandage metal strip it is necessary to put an insulating gasket with a width of 1-2 mm more than the width of the metal strip. The ends of the strip are attached to the lock or buckle. When fastening to a lock, the length of the strip is taken 10 mm more than when fastening with a buckle. With hidden laying, the wires are fixed in separate places with alabaster mortar; nailing is not allowed. To preserve the cores and insulation of flat wires when the route is rotated in the plane of the wall or ceiling at an angle of 90 °, the wires can be bent in the following ways: 1) with open wiring, it is allowed to bring the cores together by flattening the separating base or cutting it along the wire in the middle between the cores. Crossing of veins among themselves in the corners is not allowed; 2) with a hidden laying, edgewise bending is performed: the separating base between the wires, depending on the cross section and the number of wire wires, is cut into 40-60 mm and 1-2 wires are taken inside the corner in the form of a half-loop to prevent their contact. Bending along the flat side is performed as follows: the wire is bent along the flat side through an angle of 90 ° without cutting the separation base. In this case, the cores should not fit tightly to each other. To prevent such a fit, the next fastening of the wire to the building base is carried out near, but not at the bend. A wire that does not have a dividing base is bent into an edge with a radius that ensures smooth bending without insulation warpage.
For hidden wiring, branch boxes, boxes for switches and sockets must be embedded in the wall so that their edges coincide with the surface of the plaster. Branch boxes must be closed with lids. The dimensions of the boxes should allow the stock of the ends of the connected or branch wires to be placed. For open laying, branch boxes are flat and small. They are installed without lining wooden sockets. If metal boxes are used, bushings made of insulated material should be installed at the points where the wires are inserted into them, or additional insulation from a rubberized or PVC tape in 3-4 layers should be applied to the wire. The separating base when connecting wires to the clamps of switches, socket outlets, lamp sockets, etc., should be cut only in the area necessary for connection, and additional insulation from a rubberized tape should be applied to the ends of the wires. When laying hidden wires, before sealing them with wet or dry gypsum plaster, it is necessary to check the wiring for breaks in the wire cores and a short circuit between them. Author: Bannikov E.A.
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