The device of passages through walls, crossings of postings. Scheme, description

ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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The device of passages through walls, crossings of postings. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Electric installation work

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Passages through internal and external walls, partitions and interfloor ceilings should be carried out in a pipe or opening, which would make it possible to replace the electrical wiring. The passages of unarmoured cables and wires through fireproof walls and interfloor ceilings should be carried out in metal or insulating semi-solid rubber, polyvinyl chloride tubes (uncut) or in segments of plastic pipes, and through combustible walls - in insulating tubes enclosed in steel segments. The ends of metal pipes must be terminated with bushings or funnels.

The installation of insulating tubes is necessary not only to ensure the replacement of wiring, but also to strengthen the insulation of unprotected wires.

Wires with a folded seam (APRF, PRF, PRFl) are allowed to be laid through wooden walls without additional protection.

Passages can be open and closed

Open passages of wires and cables are carried out in buildings with wooden walls and ceilings. In a brick building, the passage can be made hidden, in a furrow carved into the wall, but not under a layer of plaster.

When preparing passages through walls and ceilings, it is necessary to take into account the environment of the adjoining premises. If the adjoining premises are classified as dry, then the wire in the wall is laid through one hole. When passing from a dry room to a damp, damp or outside, from damp to damp, each wire must be pulled in a separate insulating pipe.

To ensure the flow of water, the holes are made with a slight slope towards a damp, damp room or outside. From the side of the dry room, the hole is framed with an insulating porcelain or plastic sleeve, and from the side of the wet, damp or outside - with a porcelain funnel. Bushings and funnels are smeared with alabaster or cement mortar so that the collar of the bushing lies tightly on the wall surface, and the outlet of the funnel completely comes out of the wall and is directed downwards. The bushings are put on the insulating tube.

The connection of wires when leaving a dry, damp room to a damp or outside building should be carried out in a dry or damp room at the roller or in a junction box installed at the aisle.

To prevent the penetration of water, the spread of fire, open passages of cables and wires through the outer walls of the premises should be sealed with easily removable fireproof materials (mineral wool, slag, etc.) after laying the electrical wiring. Funnels on both sides are filled with an insulating compound, such as bituminous mass. Open passages through the internal walls of normal non-explosive and non-flammable premises may not be sealed.

Open passages of wires through interfloor ceilings are made in an insulating tube with protection against mechanical damage to a height of at least 1,5 m. When wires are laid hidden through interfloor ceilings, wires are passed in insulating tubes, the exits of which are terminated with porcelain funnels.

When making passes through interfloor ceilings, where protection of the wire from mechanical damage is required when it exits to the upper floor, it is forbidden to use wires of the PRD, PRHD brands (these wires are not laid in steel pipes.)

When making a passage through an interfloor ceiling, single-core insulated wires of the APR, APV, APRV, etc. brands are used. Insulated pipes in the passages should not have breaks along the length and are sealed with the outer edges of the bushings and funnels (they can protrude from them by 4-5 mm ).

It is forbidden to make passages in wooden walls at the joints between logs.

Intersections of wires and cables are not recommended. In open wiring, when unprotected wires intersect with unprotected or protected insulated wires (with a distance between them of less than 10 mm), additional insulation must be applied to the unprotected wire: a piece of a whole PVC tube is put on it or 3-4 layers of insulating tape are applied.

In brick buildings, wire crossings are carried out hidden in plastered furrows - twisted two-core wires of one of the intersected lines are laid in a furrow, putting an insulating or PVC tube on them. At the points of entry and exit of the wire from the groove, porcelain funnels are put on the insulating tube.

The device of passages through walls, intersections of wiring
Rice. 38. Bypass pipeline: 1 - wire; 2 - rubber tube; 3 - funnel

In cases where wiring is carried out with single-core wires, each of them is placed in a separate insulating tube.

Around the metal structures of buildings, beams, pipes and especially pipelines with hot liquids, condensation and rust can form, which destroy the insulation. Therefore, when crossing protected and unprotected wires and cables with pipelines (Fig. 38), the distance between them must be at least 50 mm, or wires and cables at the intersection must be laid in insulating or metal pipes embedded in the furrow. If the distance from wires and cables to pipelines is less than 250 mm, they should be additionally protected from mechanical damage at a length of at least 250 mm in each direction from the pipeline.

With open parallel laying, the distance of wires and cables, as well as the distance from the hidden laying junction boxes to pipelines, must be at least 100 mm.

When crossing hot pipelines, wires and cables must be protected from high temperatures.

Author: Bannikov E.A.

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