Wiring. General requirements

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

Wiring. General requirements

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

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2.1.13. Permissible long-term currents on wires and cables of electrical wiring should be taken according to Chapter 1.3, taking into account the ambient temperature and the laying method.

2.1.14. The cross sections of the conductive cores of wires and cables in electrical wiring must be at least those given in Table. 2.1.1. The cross-sections of the conductors for charging lighting fixtures must be taken according to 6.5.12-6.5.14. The cross sections of grounding and zero protective conductors must be selected in compliance with the requirements of Ch. 1.7.

2.1.15. In steel and other mechanically strong pipes, sleeves, boxes, trays and closed channels of building structures of buildings, it is allowed to lay wires and cables together (with the exception of mutually redundant ones):

1. All circuits of one unit.

2. Power and control circuits of several machines, panels, panels, consoles, etc., connected by a technological process.

3. Circuits that feed a complex lamp.

4. Circuits of several groups of the same type of lighting (working or emergency) with a total number of wires in the pipe no more than eight.

5. Lighting circuits up to 42 V with circuits above 42 V, provided that the wires of the circuits up to 42 V are enclosed in a separate insulating tube.

Table 2.1.1. The smallest sections of the conductive cores of wires and cables in electrical wiring

Guides	Cross section of conductors, mm²
Guides	copper	aluminum
Cords for connecting household electrical receivers	0,35	-
Cables for connecting portable and mobile power receivers in industrial installations	0,75	-
Twisted two-core wires with stranded conductors for fixed laying on rollers	1	-
Unprotected insulated wires for indoor fixed wiring:
directly on bases, on rollers, plates and cables	1	2,5
on trays, in boxes (except deaf ones):
for conductors connected to screw terminals	1	2
for cores connected by soldering:
single-wire	0,5	-
stranded (flexible)	0,35	-
on insulators	1,5	4
Unprotected insulated wires in outdoor wiring:
along walls, structures or supports on insulators; overhead line inputs	2,5	4
under awnings on rollers	1,5	2,5
Unprotected and protected insulated wires and cables in pipes, metal sleeves and blind boxes	1	2
Cables and protected insulated wires for stationary electrical wiring (without pipes, sleeves and blind boxes):
for conductors connected to screw terminals	1	2
for cores connected by soldering:
single-wire	0,5	-
stranded (flexible)	0,35	-
Protected and unprotected wires and cables laid in closed channels or embedded (in building structures or under plaster)	1	2

2.1.16. Joint laying of mutually redundant circuits, working and emergency lighting circuits, as well as circuits up to 42 V with circuits above 42 V is prohibited in one pipe, sleeve, box, bundle, closed channel of a building structure or on one tray (for an exception, see 2.1.15, item 5 and in 6.1.16, item 1.). The laying of these chains is allowed only in different compartments of boxes and trays that have continuous longitudinal partitions with a fire resistance limit of at least 0,25 hours from fireproof material.

It is allowed to lay emergency (evacuation) and working lighting circuits on different outer sides of the profile (channel, corner, etc.).

2.1.17. In cable structures, industrial premises and electrical premises for electrical wiring, wires and cables with sheaths only made of slow-burning or non-combustible materials should be used, and unprotected wires should be insulated only from slow-burning or non-combustible materials.

2.1.18. With alternating or rectified current, the laying of phase and neutral (or direct and reverse) conductors in steel pipes or insulating pipes with a steel sheath should be carried out in one common pipe.

It is allowed to lay the phase and neutral working (or direct and return) conductors in separate steel pipes or in insulating pipes with a steel sheath, if the continuous load current in the conductors does not exceed 25 A.

2.1.19. When laying wires and cables in pipes, blind boxes, flexible metal sleeves and closed channels, it must be possible to replace wires and cables.

2.1.20. Structural elements of buildings and structures, closed channels and voids of which are used for laying wires and cables, must be fireproof.

2.1.21. Connection, branching and termination of conductors of wires and cables must be carried out by crimping, welding, soldering or clamping (screw, bolt, etc.) in accordance with the current instructions approved in the prescribed manner.

2.1.22. At the junction, branch and connection of wire or cable cores, a supply of wire (cable) must be provided, which makes it possible to reconnect the branch or connection.

2.1.23. Connection points and branches of wires and cables must be accessible for inspection and repair.

2.1.24. At the junctions and branches, wires and cables should not experience mechanical tensile forces.

2.1.25. The places of connection and branching of liquid wires and cables, as well as connecting and branch clamps, etc., must have insulation equivalent to the insulation of the cores of the entire places of these wires and cables.

2.1.26. Connection and branching of wires and cables, with the exception of wires laid on insulating supports, must be carried out in junction and branch boxes, in insulating cases of connecting and branch clamps, in special niches of building structures, inside the housings of electrical installation products, devices and machines. When laying on insulating supports, the connection or branching of the wires should be carried out directly at the insulator, the clamp or on them, as well as on the roller.

2.1.27. The design of junction and branch boxes and clamps must comply with the laying methods and environmental conditions.

2.1.28. Junction and junction boxes and insulating housings of junction and junction clamps should, as a rule, be made of non-combustible or slow-burning materials.

2.1.29. Metal elements of electrical wiring (structures, boxes, trays, pipes, sleeves, boxes, brackets, etc.) must be protected from corrosion in accordance with environmental conditions.

2.1.30. Electrical wiring must be made taking into account their possible movements at the intersections with temperature and sedimentary seams.

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

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