The choice of the type of wiring, the choice of wires and cables and the way they are laid

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Section 2. Sewerage of electricity

Wiring. The choice of the type of electrical wiring, the choice of wires and cables and the way they are laid

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Encyclopedia of radio electronics and electrical engineering / Rules for the installation of electrical installations (PUE)

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2.1.31. Electrical wiring must comply with environmental conditions, the purpose and value of structures, their design and architectural features.

2.1.32. When choosing the type of wiring and the method of laying wires and cables, the requirements of electrical safety and fire safety must be taken into account.

2.1.33. The choice of types of electrical wiring, the choice of wires and cables and the method of their laying should be carried out in accordance with Table. 2.1.2.

If there are two or more conditions that characterize the environment at the same time, the electrical wiring must comply with all these conditions.

2.1.34. Sheaths and insulation of wires and cables used in electrical wiring must comply with the laying method and environmental conditions. The insulation must also match the rated mains voltage.

If there are special requirements due to the characteristics of the installation, the insulation of wires and the protective sheaths of wires and cables must be selected taking into account these requirements (see also 2.1.50. and 2.1.51.).

2.1.35. Zero working conductors must have insulation equivalent to that of the phase conductors.

In industrial normal premises, it is allowed to use steel pipes and cables of open electrical wiring, as well as metal cases of openly installed current conductors, metal structures of buildings, industrial structures (for example, trusses, columns, crane tracks) and mechanisms as one of the working conductors of the line in voltage networks up to 42 V. In this case, continuity and sufficient conductivity of these conductors, visibility and reliable welding of joints must be ensured.

The use of the above structures as a working conductor is not allowed if the structures are in close proximity to combustible parts of buildings or structures.

2.1.36. The laying of wires and cables, pipes and ducts with wires and cables, according to fire safety conditions, must meet the requirements of Table. 2.1.3.

2.1.37. During open laying of protected wires (cables) with sheaths of combustible materials and unprotected wires, the clear distance from the wire (cable) to the surface of bases, structures, parts made of combustible materials must be at least 10 mm. If it is impossible to provide the specified distance, the wire (cable) should be separated from the surface by a layer of fireproof material protruding from each side of the wire (cable) by at least 10 mm.

2.1.38. When laying hidden wires (cables) with sheaths of combustible materials and unprotected wires in closed niches, in the voids of building structures (for example, between the wall and the cladding), in furrows, etc. with the presence of combustible structures, it is necessary to protect the wires and cables with solid a layer of fireproof material on all sides.

2.1.39. In case of open laying of pipes and ducts made of slow-burning materials on non-combustible and slow-burning bases and structures, the clear distance from the pipe (duct) to the surface of structures, parts made of combustible materials should be at least 100 mm. If it is impossible to provide the specified distance, the pipe (box) should be separated on all sides from these surfaces with a continuous layer of fireproof material (plaster, alabaster, cement mortar, concrete, etc.) with a thickness of at least 10 mm.

2.1.40. In case of hidden laying of pipes and ducts made of slow-burning materials in closed niches, in the voids of building structures (for example, between a wall and lining), in furrows, etc., pipes and ducts should be separated from all sides from the surfaces of structures, parts made of combustible materials with a solid a layer of fireproof material with a thickness of at least 10 mm.

2.1.41. When crossing short sections of electrical wiring with elements of building structures made of combustible materials, these sections must be made in compliance with the requirements of 2.1.36 - 2.1.40.

2.1.42. In places where, due to high ambient temperature, the use of wires and cables with insulation and sheaths of normal heat resistance is impossible or leads to an unreasonable increase in the consumption of non-ferrous metal, wires and cables with insulation and sheaths of increased heat resistance should be used.

2.1.43. In damp and especially damp rooms and outdoor installations, wire insulation and insulating supports, as well as supporting and supporting structures, pipes, ducts and trays must be moisture resistant.

Table 2.1.2. The choice of types of electrical wiring, laying methods and wires and cables

Environmental conditions	Type of wiring and method of installation	Wires and cables
Exposed electrical wiring
Dry and wet areas	On roller skates and clicks	Bare solid wires
Dry rooms	Also	Twisted two-wire wires
Premises of all kinds and outdoor installations	On insulators, as well as on rollers intended for use in damp places. In outdoor installations, rollers for damp places (large sizes) can only be used in places where the possibility of direct rain or snow on the electrical wiring is excluded (under awnings)	Bare solid wires
outdoor installations	Directly on the surface of walls, ceilings and on strings, strips and other supporting structures	Cable in non-metallic and metal sheaths
Premises of all kinds	Also	Unprotected and protected solid and stranded wires. Cables in non-metallic and metallic sheaths
Premises of all kinds and outdoor installations	On trays and in boxes with opening lids	Also
Premises of all kinds and outdoor installations (only special wires with support cable for outdoor installations or cables)	On ropes	Special wires with carrying cable. Unprotected and protected solid and stranded wires. Cables in non-metallic and metallic sheaths
Hidden wiring
Premises of all kinds and outdoor installations	In non-metallic pipes made of combustible materials (non-self-extinguishing polyethylene, etc.). In closed channels of building structures. Under plaster. Exceptions: 1. It is forbidden to use insulating pipes with a metal sheath in damp, especially damp rooms and outdoor installations. 2. It is forbidden to use steel pipes and steel blind boxes with a wall thickness of 2 mm or less in damp, especially damp rooms and outdoor installations.	Unprotected and protected, solid and stranded wires. Cables in non-metallic sheath
Dry, wet and damp areas	Embedded in building structures during their manufacture	Bare wires
Open and hidden electrical wiring
Premises of all kinds and outdoor installations	In metal flexible sleeves. In steel pipes (ordinary and thin-walled) and deaf steel boxes. In non-metallic pipes and non-metallic blind boxes made of slow-burning materials. In insulating pipes with a metal sheath. Exceptions: 1. It is forbidden to use insulating pipes with a metal sheath in damp, especially damp rooms and outdoor installations 2. It is forbidden to use steel pipes and steel blind boxes with a wall thickness of 2 mm or less in damp, especially damp rooms and outdoor installations.	Unprotected and protected solid and stranded wires. Cables in non-metallic sheath

2.1.44. In dusty rooms, it is not recommended to use laying methods in which dust can accumulate on the electrical wiring elements, and its removal is difficult.

2.1.45. In rooms and outdoor installations with a chemically active environment, all electrical wiring elements must be resistant to the environment or protected from its effects.

2.1.46. Wires and cables with non-light-resistant outer insulation or sheath must be protected from direct sunlight.

2.1.47. In places where mechanical damage to electrical wiring is possible, openly laid wires and cables must be protected from them by their protective sheaths, and if such sheaths are absent or not sufficiently resistant to mechanical stress, by pipes, boxes, fences or the use of hidden electrical wiring.

2.1.48. Wires and cables should be used only in those areas that are specified in the standards and specifications for cables (wires).

2.1.49. For stationary electrical wiring, mainly wires and cables with aluminum conductors should be used. For exceptions, see 2.1.70, 3.4.3, 3.4.12, 5.5.6, 6.5.12-6.5.14 [in 7th edition 6.6.15-6.6.20], 7.2.53 [in 7th edition 7.2.51. 7.3.93.] and XNUMX.

It is not allowed to use wires and cables with aluminum conductors for connection to electrical devices installed directly on vibration isolating supports.

In museums, art galleries, libraries, archives and other repositories of national importance, only wires and cables with copper conductors should be used.

Table 2.1.3. The choice of types of electrical wiring and methods for laying wires and cables according to fire safety conditions

Type of electrical wiring and method of laying on bases and structures		Wires and cables
from combustible materials	from non-combustible or slow-burning materials	Wires and cables
Exposed electrical wiring
On casters, insulators or lined with fireproof materials¹⁾	Directly	Unprotected wires; sheathed wires and cables sheathed with combustible materials
Directly	"	Sheathed wires and cables sheathed from non-combustible and slow-burning materials
In pipes and boxes of non-combustible materials	In pipes and boxes made of slow-burning and non-combustible materials	Unprotected and protected wires and cables sheathed from combustible, slow-burning materials
Hidden wiring
With lining of fireproof materials¹⁾ and subsequent plastering or sewn on all sides with a continuous layer of other fireproof materials	Directly	Unprotected wires; sheathed wires and cables sheathed with combustible materials
With lining of fireproof materials¹⁾	"	Sheathed wires and cables sheathed with flame retardant materials
Directly	"	Same of non-combustible
In pipes and boxes made of fire-retardant materials - with a lining for pipes and boxes of fireproof materials¹⁾ and subsequent plastering²⁾	In pipes and ducts: from combustible materials - embedded, in furrows, etc., in a continuous layer of fireproof materials³⁾	Unprotected wires and cables sheathed with combustible, slow-burning and non-combustible materials
The same from fireproof materials - directly	The same from slow-burning and fireproof materials - directly

1. Lining of non-combustible materials should protrude from each side of the wire, cable, pipe or conduit by at least 10 mm.

2. The plastering of the pipe is carried out with a continuous layer of plaster, alabaster, etc. with a thickness of at least 10 mm above the pipe.

3. A continuous layer of fireproof material around the pipe (box) can be plaster, alabaster, cement mortar or concrete with a thickness of at least 10 mm.

2.1.50. To power portable and mobile electrical receivers, cords and flexible cables with copper conductors, specially designed for this purpose, should be used, taking into account possible mechanical effects. All cores of the specified conductors, including the grounding conductor, must be in a common sheath, braid or have a common insulation.

For mechanisms with limited movement (cranes, mobile saws, gate mechanisms, etc.), it is necessary to use such designs of current supply to them that protect the cores of wires and cables from breaking (for example, flexible cable loops, carriages for movable suspension of flexible cables).

2.1.51. In the presence of oils and emulsions in the places where the wires are laid, wires with oil-resistant insulation should be used or the wires should be protected from their effects.

See other articles Section Rules for the installation of electrical installations (PUE).

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