AS/NZS 3008.1.2:1998

1 - AS/NZS 3008.1.2:1998 ELECTRICAL INSTALLATIONS - SELECTION OF CABLES - CABLE FOR ALTERNATING VOLTAGES UP TO AND INCLUDING 0.6/1 K
4 - PREFACE
5 - CONTENTS
10 - FOREWORD
11 - SECTION 1 SCOPE AND GENERAL
11 - 1.1 SCOPE AND APPLICATION
11 - 1.1.1 Scope
11 - 1.1.2 Application
11 - 1.2 ALTERNATIVE SPECIFICATIONS
12 - 1.3 REFERENCED AND RELATED DOCUMENTS
12 - 1.3.1 Referenced documents
12 - 1.3.2 Related documents
13 - 1.4 DEFINITIONS
13 - 1.4.1 Ambient temperature
13 - 1.4.2 Continuous loading
13 - 1.4.3 Ladder support
13 - 1.4.4 Perforated tray
13 - 1.4.5 Route length
14 - SECTION 2 CABLE SELECTION PROCEDURE
14 - 2.1 GENERAL
14 - 2.2 SELECTION PROCESS
14 - 2.3 DETERMINATION OF MINIMUM CABLE SIZE BASED ON CURRENT-CARRYING CAPACITY CONSIDERATIONS
15 - 2.4 DETERMINATION OF MINIMUM CABLE SIZE BASED ON VOLTAGE DROP CONSIDERATIONS
16 - 2.5 DETERMINATION OF MINIMUM CABLE SIZE BASED ON THE SHORT-CIRCUIT TEMPERATURE CONSIDERATIONS
17 - SECTION 3 CURRENT-CARRYING CAPACITY
17 - 3.1 RATINGS
17 - 3.1.1 General
17 - 3.1.2 Basis
17 - 3.2 TYPES OF CONDUCTORS
17 - 3.2.1 Conductor material
17 - 3.2.2 Insulation material operating temperatures
18 - 3.3 TYPES OF CABLE
18 - 3.3.1 Sheathed and unsheathed thermoplastic, elastomer and XLPE cables
18 - 3.3.2 Flexible cords and cables
19 - 3.3.3 Mineral-insulated metal-sheathed (MIMS) cables
19 - 3.3.4 Aerial cables
19 - 3.3.5 Neutral-screened cables
20 - 3.3.6 High temperature elastomer, polymeric or fibrous cables and flexible cords
20 - 3.3.7 Other cable types
20 - 3.4 INSTALLATION CONDITIONS
20 - 3.4.1 General
20 - 3.4.2 Cables installed in air
21 - 3.4.3 Cables installed in thermal insulation
22 - 3.4.4 Cables buried direct in the ground
22 - 3.4.5 Cables installed in underground wiring enclosures
23 - 3.4.6 Variation of installation conditions along cable run
23 - 3.5 EXTERNAL INFLUENCES ON CABLES
23 - 3.5.1 Application of rating factors
23 - 3.5.2 Effect of grouping of cables
25 - 3.5.3 Effect of ambient temperature
26 - 3.5.4 Effect of depth of laying
26 - 3.5.5 Effect of thermal resistivity of soil
26 - 3.5.6 Effect of varying loads
26 - 3.5.7 Effect of thermal insulation
27 - 3.5.8 Effect of direct sunlight
66 - SECTION 4 VOLTAGE DROP
66 - 4.1 GENERAL
66 - 4.2 DETERMINATION OF VOLTAGE DROP FROM MILLIVOLTS PER AMPERE METRE
67 - 4.3 DETERMINATION OF VOLTAGE DROP FROM CIRCUIT IMPEDANCE
67 - 4.3.1 General
67 - 4.3.2 Single-phase, two-wire supply system
68 - 4.3.3 Three-phase, three-wire or four-wire supply system
68 - 4.3.4 Two-phase, three-wire, earthed neutral 120-degree supply system
68 - 4.3.5 Single-phase, three-wire, earthed centre-tapped 180-degree supply system
68 - 4.4 DETERMINATION OF VOLTAGE DROP FROM CABLE OPERATING TEMPERATURE
69 - 4.5 DETERMINATION OF VOLTAGE DROP FROM LOAD POWER FACTOR
70 - 4.6 DETERMINATION OF VOLTAGE DROP IN UNBALANCED MULTIPHASE CIRCUITS
90 - SECTION 5 SHORT-CIRCUIT PERFORMANCE
90 - 5.1 GENERAL
90 - 5.2 FACTORS GOVERNING THE APPLICATION OF THE TEMPERATURE LIMITS
91 - 5.3 CALCULATION OF PERMISSIBLE SHORT-CIRCUIT CURRENTS
91 - 5.4 INFLUENCE OF METHOD OF INSTALLATION
92 - 5.5 MAXIMUM PERMISSIBLE SHORT-CIRCUIT TEMPERATURES
92 - 5.5.1 General
92 - 5.5.2 Insulating materials
92 - 5.5.3 Outer sheath and bedding materials
93 - 5.5.4 Conductor and metallic sheath materials and components
94 - APPENDIX A - EXAMPLES OF THE SELECTION OF CABLES TO SATISFY CURRENT-CARRYING CAPACITY, VOLTAGE DROP AND SHORT-CIRCUIT PERFORMANC
94 - A1 EXAMPLE 1
94 - A1.1 Problem
94 - A1.2 Solution
95 - A1.3 Comparison of different methods
96 - A2 EXAMPLE 2
96 - A2.1 Problem
96 - A2.2 Solution
96 - A3 EXAMPLE 3
96 - A3.1 Problem
96 - A3.2 Solution
97 - A4 EXAMPLE 4
97 - A4.1 Problem
97 - A4.2 Solution
98 - A5 EXAMPLE 5
98 - A5.1 Problem
98 - A5.2 Solution
99 - A6 EXAMPLE 6
99 - A6.1 Problem
99 - A6.2 Solution
100 - A7 EXAMPLE 7
100 - A7.1 Problem
100 - A7.2 Solution
101 - A8 EXAMPLE 8
101 - A8.1 Problem
101 - A8.2 Solution
103 - APPENDIX B - RECOMMENDED CIRCUIT CONFIGURATIONS FOR THE INSTALLATION OF SINGLE-CORE CABLES IN PARALLEL

Sets out the procedures to be followed for the selection of cables to satisfy typical New Zealand installation conditions where the ambient air temperature is 30 degrees Celsius and ambient soil temperature is 15 degrees Celsius. Criteria given are current-carrying capacity, voltage drop and short-circuit temperature rise.

This Standard sets out a method for cable selection for those types of electrical cables and methods of installation which are in common use at working voltages up to and including 0.6/1 kV at 50 Hz a.c.Three criteria are given for cable selection, as follows:(a) Current-carrying capacity.(b) Voltage drop.(c) Short-circuit temperature rise.This Standard provides sustained current-carrying capacities and voltage drop values for those types of electrical cable and installation practices in common use in New Zealand. A significant amount of explanatory material is also provided on the application of rating factors which arise from the particular installation conditions of a single circuit or groups of circuits. Also, provided in Section 5 is information on cable selection based on short-circuit temperature limits.NOTE: A number of worked examples on cable selection are included in Appendix A.This Standard does not take into account the effects that may occur owing to temperature rise at the terminals of equipment and reference is necessary to NZS 3000 and the individual equipment Standards.ApplicationThis Standard is intended to apply to installations made or carried out after the date of publication, but it is recommended that it not be applied on a mandatory basis until 6 months after the date of publication. However, if work on an installation is commenced before publication of this edition, the inspecting authority may grant permission for the installation to be carried out in accordance with the superseded edition.

First published as AS/NZS 3608.1.2:1998.