Section 1 General Rules

Selection of conductors for heating, economic current density and corona conditions. Permissible continuous currents for wires, cords and cables with rubber or plastic insulation

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

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1.3.10. Permissible long-term currents for wires with rubber or polyvinyl chloride insulation, cords with rubber insulation and cables with rubber or plastic insulation in lead, polyvinyl chloride and rubber sheaths are given in Table. 1.3.4 - 1.3.11. They are accepted for temperatures: cores +65, ambient air +25 and ground +15 º C.

When determining the number of wires laid in one pipe (or cores of a stranded conductor), the neutral working conductor of a four-wire three-phase current system, as well as grounding and neutral protective conductors are not taken into account.

The data contained in the table. 1.3.4 and 1.3.5 should be applied regardless of the number of pipes and the location of their installation (in the air, floors, foundations).

Permissible long-term currents for wires and cables laid in boxes, as well as in trays in bundles, must be accepted: for wires - according to table. 1.3.4 and 1.3.5, as for wires laid in pipes, for cables - according to table. 1.3.6 - 1.3.8, as for cables laid in the air. If the number of simultaneously loaded wires is more than four, laid in pipes, boxes, and also in trays in bundles, the currents for the wires should be taken according to the table. 1.3.4 and 1.3.5, as for wires laid openly (in the air), with the introduction of reduction factors of 0 for 68 and 5; 6 for 0 - 63 and 7 for 9 - 0 wires.

For wires of secondary circuits, reduction factors are not introduced.

1.3.11. Permissible long-term currents for wires laid in trays for single-row installation (not in bundles) should be taken as for wires laid in the air.

Permissible long-term currents for wires and cables laid in boxes should be taken according to table. 1.3.4 - 1.3.7, as for single wires and cables laid openly (in the air), using the reduction factors indicated in table. 1.3.12.

When choosing reduction factors, control and reserve wires and cables are not taken into account.

Table 1.3.4. Permissible continuous current for wires and cords with rubber and polyvinyl chloride insulation with copper conductors

Table 1.3.5. Permissible continuous current for rubber and polyvinyl chloride insulated wires with aluminum conductors

Table 1.3.6. Permissible continuous current for wires with copper conductors with rubber insulation in metal protective sheaths and cables with copper conductors with rubber insulation in lead, polyvinyl chloride, nayrite or rubber sheaths, armored and unarmored

* Currents refer to wires and cables both with and without a neutral core.

Table 1.3.7. Permissible continuous current for cables with aluminum conductors with rubber or plastic insulation in lead, polyvinyl chloride and rubber sheaths, armored and unarmored*

*Note. Permissible continuous currents for four-core cables with plastic insulation for voltages up to 1 kV can be selected according to table. 1.3.7., as for three-core cables, but with a coefficient of 0,92.

Table 1.3.8. Permissible continuous current for portable light and medium hose cords, portable heavy duty hose cables, mine flexible hose cables, floodlight cables and portable wires with copper conductors

* Currents refer to cords, wires and cables with and without neutral core.

Table 1.3.9. Permissible continuous current for portable hose cables with copper conductors and rubber insulation for peat enterprises

* Currents refer to cables with and without neutral core.

Table 1.3.10. Permissible continuous current for hose cables with copper conductors and rubber insulation for mobile electrical receivers

* Currents refer to cables with and without neutral core.

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

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