GB/T 5023.1-2008Polyvinyl chloride insulated cables of rated voltages up to and including 450/750 V - Part 1: General requirements (English PDF)

Foreword

GB/T 5023 “Polyvinyl chloride insulated cables of rated voltages up to and including 450/750 V” is published in seven parts: Part 1: General requirements; Part 2: Test methods; Part 3: Non-sheathed cables for fixed wiring; Part 4: Sheathed cables for fixed wiring; Part 5: Flexible cables (cords); Part 6: Lift cables and cables for flexible connections; Part 7: Two-core or multicore screened and unscreened flexible cables.

This part is Part 1 of GB/T 5023. It is identical (IDT) to IEC 60227-1:2007 “Polyvinyl chloride insulated cables of rated voltages up to and including 450/750 V — Part 1: General requirements”, edition 3.0 (English version).

For ease of use, the following editorial changes were made: the decimal comma was replaced by the decimal point; the foreword of IEC 60227-1:2007 was deleted; and the informative Annex B was added.

This part replaces GB 5023.1-1997 “Polyvinyl chloride insulated cables of rated voltages 450/750 V and below — Part 1: General requirements”. Compared with GB 5023.1-1997, the main changes are as follows: the continuity of marks in 3.1.1 was revised; in 4.1.1 the requirement that red, grey and white shall not be used in any multicore cable was deleted and a note recommending that red and white be avoided was added; in 4.1.2 the note stating that the cores of unsheathed twin parallel cords need no identification was deleted and the colour schemes for three-, four- and five-core cables were revised; the light blue of the note to 4.1.3 was changed to blue; the ageing conditions of the non-contamination test for PVC/E in Table 1 were changed to (100 ± 2) °C, 10 x 24 h; 5.5.1 added the 90 °C polyvinyl chloride sheathing compound PVC/ST10, whose full performance data were added to Table 2; for item 8, the low temperature impact test, in Tables 1 and 2, the test temperature was set at -15 °C to suit the climatic conditions of China, and may also be adjusted at the customer’s request; and cable types 56, 57 and 71c were added to Annex A — 56, 90 °C heat-resistant light polyvinyl chloride sheathed cord (60227 IEC 56); 57, 90 °C heat-resistant ordinary polyvinyl chloride sheathed cord (60227 IEC 57); and 71c, circular polyvinyl chloride sheathed lift cable and cable for flexible connection (60227 IEC 71c).

Annex A of this part is normative; Annex B is informative.

This part was proposed by the China Electrical Equipment Industry Association and is under the jurisdiction of the National Technical Committee on Wires and Cables of Standardization Administration of China (SAC/TC 213).

Responsible drafting organization: Shanghai Electric Cable Research Institute. Participating drafting organizations: Baosheng Science and Technology Innovation Co., Ltd.; Changshu Cable Factory; Jiangsu Shangshang Cable Group Co., Ltd.; Far East Cable Factory; Tianjin Jinshan Electric Wire and Cable Co., Ltd.; Zhejiang Wanma Cable Co., Ltd.

Principal drafters: Yan Yongchang, Fang Quansheng, Qian Guofeng, Li Bin, Wang Chuanbin, Zheng Guojun, Zheng Hong.

The previous editions of the standard replaced by this part are GB 5023.1-1985 and GB 5023.1-1997.

1 General

1.1 Scope. This part of GB/T 5023 applies to polyvinyl chloride insulated and, where present, polyvinyl chloride sheathed flexible and rigid cables of rated voltage U0/U up to and including 450/750 V, used in power installations of nominal AC voltage not exceeding 450/750 V.

NOTE: for certain types of flexible cable the term “cord” may be used.

The individual cable types are specified in GB/T 5023.3, GB/T 5023.4 and the other product parts; the method of designating cable types is given in Annex A. The test methods specified in Parts 1, 3 and 4 of GB/T 5023 are given in GB/T 5023.2, GB/T 18380.12-2008 and the relevant parts of GB/T 2951-2008.

1.2 Normative references. The provisions of the following documents become provisions of this part through reference in it. For dated references, subsequent amendments (excluding corrections) or revisions do not apply to this part; however, parties to agreements based on this part are encouraged to investigate whether the latest editions may be used. For undated references, the latest edition applies.

GB/T 2951.11-2008 Common test methods for insulating and sheathing materials of electric and optical cables — Part 11: Methods for general application — Measurement of thickness and overall dimensions — Tests for determining the mechanical properties (IEC 60811-1-1:2001, IDT) · GB/T 2951.12-2008 Part 12: Methods for general application — Thermal ageing methods (IEC 60811-1-2:1985, IDT) · GB/T 2951.14-2008 Part 14: Methods for general application — Tests at low temperature (IEC 60811-1-4:1985, IDT) · GB/T 2951.21-2008 Part 21: Methods specific to elastomeric compounds — Ozone resistance, hot set and mineral oil immersion tests (IEC 60811-2-1:2001, IDT) · GB/T 2951.31-2008 Part 31: Methods specific to PVC compounds — High temperature pressure test — Test for resistance to cracking (IEC 60811-3-1:1985, IDT) · GB/T 2951.32-2008 Part 32: Methods specific to PVC compounds — Loss of mass test — Thermal stability test (IEC 60811-3-2:1985, IDT) · GB/T 3956-1997 Conductors of insulated cables (idt IEC 60228:1978) · GB/T 5023.2-2008 Polyvinyl chloride insulated cables of rated voltages up to and including 450/750 V — Part 2: Test methods (IEC 60227-2:2003, IDT) · GB/T 5023.3-2008 Part 3: Non-sheathed cables for fixed wiring (IEC 60227-3:1997, IDT) · GB/T 5023.4-2008 Part 4: Sheathed cables for fixed wiring (IEC 60227-4:1997, IDT) · GB/T 5023.5-2008 Part 5: Flexible cables (cords) (IEC 60227-5:2003, IDT) · GB/T 18380.12-2008 Tests on electric and optical fibre cables under fire conditions — Part 12: Test for vertical flame propagation for a single insulated wire or cable — Procedure for 1 kW pre-mixed flame (IEC 60332-1-2:2004, IDT) · IEC 173:1964 Colours of the cores of flexible cables and cords · IEC 62440 Electric cables of rated voltages up to and including 450/750 V — Guide to use

2 Terms and definitions

The following terms and definitions apply to all parts of GB/T 5023.

2.1 Definitions relating to insulating and sheathing materials. 2.1.1 Polyvinyl chloride compound (PVC): a material whose characteristic constituent is polyvinyl chloride or one of its copolymers, suitably selected, compounded and processed; the term also covers a compound containing polyvinyl chloride together with a polyvinyl chloride polymer. 2.1.2 Type of compound: compounds are classified by the performance measured in the specified tests; the type has no direct relation to the composition of the compound.

2.2 Definitions relating to the tests. 2.2.1 Type tests (symbol T): tests carried out before supplying, on a general commercial basis, a type of cable covered by GB/T 5023, in order to demonstrate that the cable has satisfactory performance and meets the intended service requirements. Type tests are by nature such that, once carried out, they need not be repeated; they shall be repeated if a change in cable materials or design would affect the performance of the cable. 2.2.2 Sample tests (symbol S): tests carried out on samples of completed cable, or on components taken from completed cable, to verify that the finished product complies with the design specification.

2.3 Rated voltage. The rated voltage is the reference voltage for which the cable is designed and on which its electrical tests are based. It is expressed as U0/U in volts. U0 is the r.m.s. voltage between any insulated conductor and “earth” (the metallic covering of the cable or the surrounding medium). U is the r.m.s. voltage between any two phase conductors of a multicore cable or of a system of single-core cables.

In an alternating current system, the rated voltage of a cable shall be at least equal to the nominal voltage of the system in which it is used; this condition applies to both the U0 value and the U value. In a direct current system, the nominal voltage of the system shall be not greater than 1.5 times the rated voltage of the cable.

NOTE: the operating voltage of a system may permanently exceed the nominal voltage of that system by 10 %; a cable whose rated voltage is at least equal to the nominal voltage of the system may be used at an operating voltage 10 % above its rated voltage.

3 Marking

3.1 Indication of origin and cable identification. The cable shall bear a continuous mark giving the manufacturer’s name, the product type and the rated voltage; the manufacturer’s mark may be an identification thread or a repeated mark of the name or trade mark of the manufacturer. The method of designating the product type is given in Annex A. For a cable used where the conductor temperature exceeds 70 °C, the identification mark may state the type or the maximum conductor temperature. Marks may be printed in ink or embossed on the insulation or the sheath.

3.1.1 Continuity of marks. The distance between the end of one complete mark and the beginning of the next shall not exceed 550 mm on the outer sheath of the cable, and shall not exceed 275 mm on the insulation or on the tape of the following cables: a) the insulation of non-sheathed cables; b) the insulation of sheathed cables; c) the tape inside a sheathed cable.

3.1.2 Durability. Printed ink marks shall be durable. Compliance shall be checked by the test specified in 1.8 of GB/T 5023.2-2008.

3.1.3 Legibility. All marks shall be legible. The colour of an identification thread shall be readily identifiable or easily recognizable, if necessary after cleaning with petrol or another suitable solvent.

3.2 Product designation. The product shall be designated by its type, its specification and the standard number. The specification includes the rated voltage, the number of cores and the nominal cross-sectional area of the conductor. The cable packaging shall carry a label or mark stating the product type, the specification, the standard number, the manufacturer’s name and the place of origin. The designation of the GB 5023.1 to GB 5023.3-1985 products and its cross-reference with the GB/T 5023-2008 product types is given in Annex B.

4 Identification of insulated cores

Each insulated core shall be identified as follows: cables of five cores or fewer shall be identified by colour, see 4.1; cables of more than five cores shall be identified by numerals, see 4.2.

NOTE: colour schemes, in particular those for multicore rigid cables, are under consideration.

4.1 Identification of insulated cores by colour. 4.1.1 General: the insulated cores of a cable shall be identified by coloured insulation or by another suitable method, and, apart from cores identified by the green/yellow combination, each insulated core of a cable shall use one colour only. Green alone and yellow alone, that is not in combination, shall not be used in any multicore cable. NOTE: the use of red and white should be avoided.

4.1.2 Colour schemes. The preferred colour schemes for flexible cables and single-core cables are: single-core cable — no preferred scheme; two-core cable — no preferred scheme; three-core cable — green/yellow, blue, brown, or brown, black, grey; four-core cable — green/yellow, brown, black, grey, or blue, brown, black, grey; five-core cable — green/yellow, blue, brown, black, grey, or blue, brown, black, grey, black. The colours shall be clearly identifiable and durable; durability shall be checked by the test specified in 1.8 of GB/T 5023.2-2008.

4.1.3 The green/yellow combination. The distribution of the two colours on a green/yellow core shall meet the following condition (in accordance with IEC 60173:1964): for every 15 mm length of the core, one of the colours shall cover at least 30 % and not more than 70 % of the surface of the core, the other colour covering the remainder. NOTE: where the green/yellow combination is used as specified above it identifies a core intended exclusively for earthing or a similar protective purpose, while blue identifies the core connected to the neutral; where there is no neutral, blue may be used to identify any core other than an earthing or protective conductor.

4.2 Identification of insulated cores by numerals. 4.2.1 General: the insulation shall be of one and the same colour and the cores shall be arranged in numerical order, except for a green/yellow core where present; a green/yellow core, where present, shall meet 4.1.3 and shall be placed in the outer layer. Numbering shall start from 1 in the innermost layer. The numerals shall be printed in Arabic figures on the outer surface of the core, all of the same colour and in clear contrast with the colour of the insulation, and shall be legible.

4.2.2 Preferred arrangement of the marks. The numeral marks shall be repeated along the core at equal intervals, with adjacent pairs of marks inverted with respect to each other. Where a mark consists of a single figure, a dash shall be placed beneath it; where it consists of two figures, they shall be arranged one above the other with a dash beneath the lower figure. The distance d between two adjacent groups of numeral marks shall be not greater than 50 mm.

4.2.3 Durability. Numeral marks shall be durable; compliance shall be checked by the test specified in 1.8 of GB/T 5023.2-2008.

5 General requirements for cable construction

5.1 Conductors. 5.1.1 Material: the conductor shall be of annealed copper wire; copper alloy solid wire may also be used for tinsel cords. The wires of the conductor may be plain or tinned. 5.1.2 Construction: the maximum diameter of the wires of a flexible conductor (other than the conductor of a tinsel cord) and the minimum number of wires of a rigid conductor shall comply with GB/T 3956-1997; the conductor class used for each cable type is given in the product standards (GB/T 5023.3-2008, GB/T 5023.4-2008 and others). The conductor of a cable for fixed installation shall be a circular solid, circular stranded or compacted circular stranded conductor. Each conductor of a tinsel cord shall consist of stranded or bunched tinsel strands, each strand being made of one or more flattened copper or copper alloy wires wound helically over a cotton, polyamide or similar textile core. 5.1.3 Checking of the construction: compliance with 5.1.1, 5.1.2 and GB/T 3956-1997 shall be checked by inspection and measurement. 5.1.4 Resistance: the resistance of each conductor of the cable, other than a tinsel cord, at 20 °C shall comply with the values specified in GB/T 3956-1997 for the conductor concerned; compliance shall be checked by the test method specified in 2.1 of GB/T 5023.2-2008.

5.2 Insulation. 5.2.1 Material: the insulation shall be one of the following polyvinyl chloride compounds, as specified for each cable type in the product standards (GB/T 5023.3-2008, GB/T 5023.4-2008 and others): type PVC/C for cables for fixed installation, type PVC/D for flexible cables, and type PVC/E for heat-resistant cables for internal wiring. The test requirements for the different types of compound are given in Table 1, and the maximum temperature of the cables made with them is given in the corresponding product standard. 5.2.2 Extruded insulation: the insulation shall be tightly extruded onto the conductor and, for cables other than tinsel cords, shall be removable without damage to the insulation, the conductor or the tin coating where present; compliance shall be checked by inspection and by manual measurement. 5.2.3 Thickness: the mean value of the thickness of the insulation shall be not less than the value specified in the tables of the product standards for each type and size of cable, but the thickness at any point may fall below the specified value provided it is not less than 90 % of that value minus 0.1 mm; compliance shall be checked by the test method specified in 1.9 of GB/T 5023.2-2008. 5.2.4 Mechanical properties before and after ageing: the insulation shall have adequate mechanical strength and elasticity over the normal range of service temperatures; compliance shall be checked by the tests specified in Table 1.

5.3 Fillers. 5.3.1 Material: unless otherwise specified in the product standards, the filler shall consist of one, or any combination, of the following materials: non-vulcanized rubber or plastic compound; natural or synthetic textile; paper. Where non-vulcanized rubber is used as the filler, its composition shall not interact harmfully with the insulation or the sheath. 5.3.2 Covering: the product standards state, for each cable type, whether a filler is present or whether the sheath or the inner covering fills the space between the insulated cores. The filler shall fill the interstices between the insulated cores so as to form a practically circular assembly, and shall not stick to the insulated cores; the laid-up cores and the filler may be bound together with a film or with tapes.

5.4 Inner covering. 5.4.1 Material: unless otherwise specified in the product standards, an extruded inner covering shall consist of a non-vulcanized rubber or plastic compound; where non-vulcanized rubber is used its composition shall not interact harmfully with the insulation or the sheath, and compliance shall be checked by the test method specified in 8.1.4 of GB/T 2951.12-2008. 5.4.2 Extruded inner covering: the inner covering shall be extruded over the insulated cores and may fill the interstices between them so as to form a practically circular assembly; it shall not stick to the insulated cores. The product standards state, for each cable type, whether an extruded inner covering is present or whether the outer sheath may fill the interstices between the cores. 5.4.3 Thickness: unless otherwise specified in the product standards, the thickness of an extruded inner covering is not required to be measured.

5.5 Sheath. 5.5.1 Material: the sheath shall be one of the polyvinyl chloride compounds specified for each cable type in the product standards: type PVC/ST4 for cables for fixed installation, type PVC/ST5 for flexible cables, type PVC/ST9 for oil-resistant sheathed flexible cables and type PVC/ST10 for 90 °C polyvinyl chloride sheathed cables. The test requirements for the different types of compound are given in Table 2. 5.5.2 Extruded sheath: the sheath shall be applied in a single layer, extruded over the insulated core for a single-core cable and over the laid-up cores and the filler or the inner covering, where present, for other cables. The sheath shall not stick to the insulated cores; a separating layer of film or tape may be applied under the sheath. Where the product standards so specify, the sheath may fill the interstices between the laid-up cores. 5.5.3 Thickness: the mean value of the thickness of the sheath shall be not less than the value specified in the tables of the product standards for each type and size, but the thickness at any point may fall below the specified value provided it is not less than 85 % of that value minus 0.1 mm; compliance shall be checked by the test method specified in 1.10 of GB/T 5023.2-2008. 5.5.4 Mechanical properties before and after ageing: the sheath shall have adequate mechanical strength and elasticity over the normal range of service temperatures; compliance shall be checked by the tests specified in Table 2.

5.6 Tests on the completed cable. 5.6.1 Electrical performance: the cable shall have adequate dielectric strength and insulation resistance; compliance shall be checked by the tests specified in Table 3. 5.6.2 Overall dimensions: the mean overall dimensions of the cable shall lie within the range given in the tables of the product standards, and for a circular sheathed cable the difference between any two overall diameters measured on the same cross-section (ovality) shall not exceed 15 % of the specified upper limit of the mean overall diameter; compliance shall be checked by the test method specified in 1.11 of GB/T 5023.2-2008. 5.6.3 Mechanical strength of flexible cables: a flexible cable shall withstand the bending and the other mechanical stresses of normal use. Where the product standards so specify, compliance shall be checked by the test methods of Clause 3 of GB/T 5023.2-2008. 5.6.3.1 Flexing test for flexible cables: see 3.1 of GB/T 5023.2-2008; after 15 000 reciprocating movements, that is 30 000 single movements, the flexible cable shall show neither interruption of the current nor a short circuit between conductors, and the sample shall then withstand the voltage test of 2.2 of GB/T 5023.2-2008. 5.6.3.2 Flexing test for tinsel cords: see 3.2 of GB/T 5023.2-2008; after 60 000 bidirectional flexings, that is 120 000 single flexings, the tinsel cord shall show no interruption of the current, and the sample shall then withstand the voltage test of 2.2 of GB/T 5023.2-2008.