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

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

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Before proceeding with the installation of electrical wires, it is necessary to determine the installation locations at the input of the shield with the meter, switches, sockets, junction boxes, lamps, and also mark the installation locations of electrical equipment (electrical appliances) and the places where the wires enter the building. After marking the electrical equipment, the routes (lines) for laying electrical wires are immediately marked.

Mark the path of laying the main line of wires, branches from it, places of turns and passages through the walls. Here, for all types of wiring, one rule applies: the wires along the walls are located either along strictly horizontal or strictly vertical lines; angles of turns of the electrical wiring route - 90 °. At the same time, it is best to lay horizontal sections of electrical wiring at a distance of 10-20 cm from the ceiling, along lines parallel to the junction of the ceiling and walls (this arrangement reduces the risk of mechanical damage to electrical wiring). But this rule also has an exception: on interfloor or attic floors, wires are laid along the shortest distance from the junction box to the place where the ceiling lamp is attached. Routes of open electrical wiring are applied as follows. The marking cord is stained with chalk, charcoal, blue or other dyes. One end is fixed on the base, the other (with an attached load) is pulled with one hand parallel to the walls or ceiling, taking into account the architectural lines of the room, and with the other hand, first pull the cord from the marking surface, then release it (Fig. 26).

Preparatory work before the installation of electrical wiring. Marking work
Rice. 26. Marking the wiring route using: a - marking cord with a plumb line, b - template: 1 - marking cord; 2 - plumb; 3 - line (route) of electrical wiring; 4 - template.

The cord, hitting the surface, leaves a clear, straight mark on it. On the routes of electrical wiring obtained in this way, the places where the wires are attached to the walls or ceiling are marked. And you should start marking the places for attaching wires from the end points of attachment. When performing hidden electrical wiring laid in ceilings, the route is marked in the shortest way, and along the walls - horizontally (parallel to the ceiling) or vertically (parallel to the corners of the walls).

Mounting points for branching boxes, regardless of the type of wiring, or box, are installed at the points of branches of wires from the main line (when descending to sockets, switches). The marking of places for installing sockets and switches is done, guided by the following considerations. If the switch must be installed at the entrance to the room (inside or outside the room), then the installation location is chosen so that the door does not touch the switch. The distance from the wires suitable for the switch to the door jamb must be at least 100 mm, the same distance must be when laying the wires near the window. The installation height of sockets and switches depends on various factors for the purpose of the room, the convenience of connecting electrical appliances, the interior (everything must be consistent with safety requirements). The standard height for installing sockets is 50-100 cm from the floor. Safety precautions do not allow the placement of sockets near grounded metal devices (water and gas pipes, central heating batteries, sinks, gas and electric stoves), the minimum distance from such devices to the socket is 50 cm. You can install them under baseboards or in an electrical baseboard if the sockets are equipped with a device that covers their conductive parts when the plug is removed.

The same rules prohibit the installation of sockets and switches in rooms with high humidity: showers, toilets and bathrooms, as well as in locker rooms with shower rooms. Plug sockets in bathrooms can only be installed if the electrical wiring in them is connected to the public network through a separating transformer. Sockets on the wall separating two rooms of the same apartment are placed on each side of the wall opposite each other and connected to the electrical wiring circuit in parallel, through a hole punched in the wall. With open wiring, it is necessary to mark the installation sites of wooden or plastic sockets, the diameter of which is 50-60 mm, the thickness is 100 mm.

With hidden wiring, hidden switches and socket outlets are installed, which are installed in boxes with a diameter of 70 mm and rectangular boxes. The locations of such boxes should be marked. When laying hidden electrical wiring, it is better to transfer its markup to paper and save the resulting plan (it will certainly come in handy in case of possible repair of electrical wiring). There are two standards for installing switches - 50-80 and 150 cm from the floor. Installation of the switch on the ceiling is allowed when turning it on and off from the floor with a cord. In children's rooms, the installation height of the switch must be at least 180 cm from the floor. In those rooms where children cannot access the switches, they can be installed at a height of at least 150 cm from the floor.

Mark the place of installation of the shield with the electric meter. As a rule, it is installed near the entrance to the building (apartment), in a heated room at a height of 1,5-1,7 m from the floor. The installation locations of the fixtures are determined as follows. If one lamp is installed in the room, then two diagonal lines are marked on the floor of the room. They mark the point of intersection of the diagonals and transfer it from the floor to the ceiling with the help of a pole to which a plumb line is attached. The upper end of the pole is installed on the ceiling so that it is exactly at the point of intersection of the diagonals marked on the floor (Fig. 27).

Preparatory work before the installation of electrical wiring. Marking work
Rice. 27. Marking the places for installing lamps: 1 - pole; 2 - plumb; 3 - the point of intersection of the diagonals.

If it is necessary to install two lamps in the room, then proceed as follows. Mark the center line along the center along the room and mark points on it located at a distance of B: 4 from the transverse walls, where

B is the length of the room. These two points obtained on the floor are transferred to the ceiling with the help of a pole with a plumb line.

The next stage of the preparatory stage of electrical work is procurement, including the collection and preparation of wires, cables, and electrical components necessary for work. First of all, this is cutting wires and cables: they are cut into segments, the length of which should ideally be equal to the distance between the junction boxes and the junction box and the consumer of electric current (socket, switch, lamp). 10-15 cm are added to the net length of each segment to connect the wires to each other and connect to the contacts of the electrical components. (If the length of a separate section of electrical wiring, for example, from one junction box to another, exceeds the length of the existing wire and the segment has to be made up of 2-3 pieces, then the places where they are connected to each other are placed in specially installed junction boxes.)

This stage also involves cutting and installing tubes through which the wires will pass through the walls.

Author: Korshevr N.G.

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