Preparatory work before the installation of electrical wiring. Punch work. Scheme, description

ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Preparatory work before the installation of electrical wiring. Punch work. Encyclopedia of radio electronics and electrical engineering

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At this stage, grooves are punched for hidden electrical wiring, socket (blind) holes for installing junction boxes (and, if necessary, junction boxes), boxes for switches and sockets, through holes in the walls for laying wires from room to room and through holes in the ceiling for fastening hooks for hanging ceiling lights.

Despite the apparent simplicity, this is a rather laborious operation. When choosing a method for obtaining nests and holes in concrete bases, one should pay attention not only to the brand of concrete, but also to the type of inert filler. Brick- or limestone-filled concrete can be drilled. If the filler is granite or sandstone (in slag concrete), then this is extremely difficult to do.

To obtain nests and holes, working tools equipped with hard alloy plates are used, for example, drills, crowns with a set of accessories, bolts, drills, punches. For drilling holes for dowels, drills with a diameter of 5-8 mm are used, for making passages - drills with a diameter of 20 and 25 mm, crowns with a diameter of 78 and 108 mm. Bolts can be in five sizes (from 16 to 26 mm), drills - in six sizes (from 18 to 30 mm). With concrete filled with crushed granite or pebbles (it has a high hardness), it is easiest to deal with a perforator - a manual electric percussion-rotary machine. In brick and concrete foundations, nests are punched with a mandrel of the OPKMU type with a punch. The mandrel's polyethylene cover has a locking screw to hold the punch in the mandrel. For punching sockets with a diameter of 5,8 and 7,8 mm, manual punches are used, respectively, PO-1U1 and PO-2U1, which make holes for dowels.

Instead of special mandrels with punches, you can use a piece of round steel with a diameter of 18-20 mm with a socket drilled from one end, into which the tail of the drill with a carbide tip is inserted. To keep the drill in the mandrel, on the side of it, opposite the middle of the nest, a hole is drilled, threaded and a locking screw is screwed in.

Holes and nests are drilled with an electric drill that has double insulation (the presence of double insulation is indicated by a sign on the device body).

Drills must be carbide-tipped, their size must be selected taking into account the depth of the wires. Sampling of nests in gypsum partitions and brick walls for laying wires with hidden wiring is performed by a mechanism for sampling furrows of the MVB-2MU1 type, which allows making furrows 8 mm wide and 20 mm deep. This mechanism is put into action with the help of an IE-1022A electric drill. The selection of furrows in plastered surfaces, gypsum and brick walls is carried out with furrow makers for the IE-1032 electric drill. Instead of furrow-making attachments, you can use an electric drill and a metal vulcanite circle with a diameter of 50-100 mm (Fig. 28). To ensure electrical safety, the electric drill must have double insulation, if it is not there, then the electric drill should be connected to the 220 V network only through a residual current device (AZO), for example, type RCD 010.2.OPUKHL2.

Preparatory work before the installation of electrical wiring. Punching works
Rice. 28. Device for sampling furrows in gypsum partitions of brick walls: 1 - electric drill shaft; 2 - housing of the furrower attachment; 3 - bead; 4 - sandpaper pads; 5 - volcanic circle; 6 - nut.

In cases where the open wiring line must be protected from the effects of an aggressive environment (dampness, explosive gas mixtures, reactive gases) or from mechanical damage, the wires are laid in steel, plastic (polyethylene, polypropylene, vinyl plastic) pipes or metal flexible hoses. Their marking and cutting is carried out within the framework of the same procurement stage. The diameter of the pipes is chosen depending on the number and diameter of the wires of a particular electric line.

When preparing steel pipes, they are inspected, crumpled are rejected, bent are straightened; then they are cleaned of rust, dirt and painted (both outside and inside). Cutting is done with a hacksaw (the cut must be processed with files, otherwise the burrs can damage the wire insulation). The use of plastic pipes is possible only at an ambient temperature of not more than 60 ° C. Since plastic is easily bent, during assembly, the pipe can not be connected at the turns of the route, but pre-bent, heated to a temperature of 100-130 ° C.

Author: Korshevr N.G.

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