The Wiring of Premises - Part 1: Low-voltage Installations

The wiring of premises

Part 1: Low-voltage installations

Warning

This standard references other documents normatively.

Foreword

With the first edition of this part of S.A.N.S 10142, the standard was subdivided and now consists of the following parts, under the general title The wiring of premises:

Part 1: Low-voltage installations.

Part 2: Medium-voltage installations above 1 kilovolts a.c. not exceeding 22 kilovolts a.c. and up to and including 3 M.V.A installed capacity.

Table 4.1 contains a list of the applicable standards for the components that may be installed in an electrical installation.

Table 4.1 summary: Applicable safety and performance standards for various electrical commodities. The majority of items are governed by safety standards, such as Aerial bundled conductors under SANS 1418-1 and most circuit-breakers under VC 8036 or SANS 556-1, depending on their rated current and breaking capacity. Some commodities are instead defined by recommended performance standards, including Busbars under SANS 1195, Cable glands under SANS 1213, Conduit under several SANS 61386 standards, and Earth rods under SANS 1063. For complex items like earth leakage circuit-breakers and switches, the applicable safety standards vary based on the rated leakage current and voltage, moving from VC 8035 for lower thresholds to SANS 60947-2 for higher thresholds.

Information on national legislation that applies only in South Africa is given in text boxes in the introduction (see page 3).

Introduction

In this edition an attempt has been made to move towards the I.E.C codes: extra low voltage (below 50 5) and d.c. applications (up to 1.5 kilovolts) have been introduced as new requirements owing to the extensive usage of, and increased fire risk that result from, high load currents. This part of S.A.N.S 10142 does not intend to cover the L.V control circuits of machinery or system components that are external circuits between separately installed parts of the machinery or system components.

This part of S.A.N.S 10142 includes certain provisions which are for information and guidance only. These provisions do not use the word "shall" and they can be found in the text, in the notes and in the informative annexes. Except in tables, notes are always for information only.

The aim of this part of S.A.N.S 10142 is to ensure that people, animals and property are protected from hazards that can arise from the operation of an electrical installation under both normal and fault conditions. An electrical installation has to provide protection against:

- – shock current.

- – overcurrent,

- – fault current.

- overvoltage.

- – undervoltage.

- – excessive temperatures, and

- – electric arcs.

If any of the above arises, the protection should automatically disconnect the supply or limit currents and voltages to safe values. In the case of undervoltage, the protection should ensure that dangerous situations, due to the loss and restoration of supply (for example, to a motor), or due to a drop in voltage, cannot occur.

This part of S.A.N.S 10142 is concerned with ensuring the basic safety of electrical installations. To ensure the protection of people, animals and property and the proper functioning of an installation, the designer of an electrical installation should be aware of:

a) the characteristics of the power supply.

b) the nature of the demand, and

c) the operating environment of each part of the installation.

It is especially important to be aware of the activities of occupants of a building. For example, the occupants might be engaged in wet processes or in the handling of flammable or explosive materials. These activities will influence the design of the installation. If a client wants more safety features for the installation than those prescribed in this part of S.A.N.S 10142, such features have to be included in the contract documentation.

The provisions of this part of S.A.N.S 10142 apply only to the selection and application of electrical equipment, appliances and accessories, which are part of the fixed electrical installation. They do not apply to the construction and safety of the equipment, appliances and accessories; those aspects are dealt with in other standards.

The Mine Health and Safety Act, 1996, which is administered by the Chief Inspector of Mines of the Department of Minerals and Energy, requires that certain prescribed electrical installations on mines comply with the requirements of S.A.N.S 10142 to 1. It also requires that a competent person, as defined, will be responsible to ensure that those prescribed electrical installations are in accordance with the standard.

The Occupational Health and Safety Act, 1993 (O.H.S Act), which is administered by the Chief Inspector of Occupational Health and Safety of the Department of Labour, requires that electrical installations comply with the requirements of S.A.N.S 10142 to 1. It also requires that a registered person, as defined (master installation electrician, installation electrician or electrical tester for single phase), will issue a Certificate of Compliance together with a test report. The certificate shall be in the form of the Certificate of Compliance published in the Electrical Installation Regulations, 2012, and the test report shall be in the form of the test report in this part of S.A.N.S 10142 (see 8.7).

In terms of the O.H.S Act, the provisions of this part of S.A.N.S 10142 apply only from the point of control to the point of consumption.

Because this part of S.A.N.S 10142 is continually updated, problems can arise on which version of the standard will be applicable when a contract is signed. The date of approval of the latest revision or amendment of this part of S.A.N.S 10142 will be the implementation date of the revision or amendment. The applicable version of this part of S.A.N.S 10142 is the one with the latest implementation date before the contract date. So contracts signed before the approval of an amendment shall be carried out in accordance with the provisions of the unamended standard. If an existing installation is extended or altered, such extension or alteration shall comply with the provisions of this part of S.A.N.S 10142 that were applicable at the time of the erection of the extension or alteration.

The edition of the standard that was applicable at the date of erection of an electrical installation is to be considered the edition defining the requirements applicable to that particular electrical installation.

Contents

S.A.N.S 10142 to 1:2017 Edition 2

S.A.N.S 10142 to 1:2017 Edition 2

S.A.N.S 10142 to 1:2017 Edition 2

S.A.N.S 10142 to 1:2017 Edition 2

S.A.N.S 10142 to 1:2017 Edition 2

S.A.N.S 10142 to 1:2017 Edition 2

S.A.N.S 10142 to 1:2017 Edition 2

S.A.N.S 10142 to 1:2017 Edition 2

Contents (concluded)

The wiring of premises

Part 1: Low-voltage installations

1 Scope

1.1 Application of This Part of S.A.N.S 10142

This part of S.A.N.S 10142 applies to electrical installations of a) residential premises.

b) commercial premises.

c) public premises,

d) industrial premises,

e) prefabricated buildings.

f) fixed surface installations on mining properties.

g) construction and demolition site installations.

h) agricultural and horticultural premises.

1) caravan sites and similar sites.

j) marinas, pleasure craft and house boats,

k) medical locations.

1) exhibitions, fairs and other temporary installations.

m) extra low voltage lighting installations.

n) electrical installations for street lighting and street furniture, and

o) equipment enclosures (structures that provide physical and environmental protection for telecommunication equipment).

1.2 Aspects Covered by This Part of S.A.N.S 10142

This part of S.A.N.S 10142 covers a) circuits supplied at nominal voltages up to and including 1 000 V a.c. or 1 500 V d.c. The standard frequency for a.c. is 50 Hz. The use of other frequencies for special purposes is not excluded.

b) circuits, other than the internal wiring of apparatus, that operate at voltages exceeding 1 000 V and are derived from an installation that has a voltage not exceeding 1 000 V a.c.,

c) any wiring systems and cables not specifically covered by the standards for appliances.

d) all consumer installations external to buildings.

e) fixed wiring in the power supply circuits for telecommunication equipment, signalling equipment, control equipment and the like (excluding internal wiring of apparatus),

f) the extension or alteration of the installation and also parts of the existing installation affected by the existing extension or alteration.

g) fixed wiring needed to connect the various units of complex machinery that are installed in separate locations.

h) equipment for which no standard is referenced.

1) replacement or maintenance of components, and

j) earthing arrangements.

1.3 Where this part of S.A.N.S 10142 is not applicable

This part of S.A.N.S 10142 does not apply to a) electric traction equipment.

b) automotive electrical equipment excluding the caravan part of a roving vehicle.

c) electrical installations on board ships. d) electrical installations in aircraft.

e) electrical installations for underground and open cast mining operations.

f) telecommunication, television and radio circuits (excluding the power supply to such equipment),

g) lightning protection of buildings and structures, and

Note The installation of surge protection is not compulsory, but where it is installed, compliance with annex I is required.

h) extra low voltage control circuits between different parts of machinery or system components, forming a unit, that are separately installed and derived from an independent source or an isolating transformer (excluding E.L.V lighting circuits).

1.4 Electrical equipment

Electrical equipment is dealt with only as far as its selection and application in the installation are concerned. This also applies to assemblies of electrical equipment that comply with the relevant standards.

2 Normative references

The following referenced documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. Information on currently valid national and international standards can be obtained from the S.A.B.S Standards Division.

- I.E.C 60664 to 1, Insulation coordination for equipment within low-voltage systems – Part 1: Principles, requirements and tests.

- I.E.C 60695-2-10, Fire hazard testing – Part 2 to 10: Glowing/hot-wire based test methods – Glow-wire apparatus and common test procedure.

- I.E.C 61557 to 8, Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. – Equipment for testing, measuring or monitoring of protective measures – Part 8: Insulation monitoring devices for I.T systems.

I.E.C 62116, Utility-interconnected photovoltaic inverters – Test procedure of islanding prevention measures.

S.A.N.S 164 to 0, Plug and socket-outlet systems for household and similar purposes for use in South Africa – Part 0: General and safety requirements.

S.A.N.S 164 to 1, Plug and socket-outlet systems for household and similar purposes for use in South Africa – Part 1: Conventional system, 16 A 250 V a.c.

S.A.N.S 164 to 2, Plug and socket-outlet systems for household and similar purposes for use in South Africa – Part 2: I.E.C system, 16 A 250 V a.c.

S.A.N.S 164-2-1, Plug and socket-outlet systems for household and similar purposes for use in South Africa – Part 2 to 1: Partially dedicated system, 16 A 250 V a.c.

S.A.N.S 164-2-2, Plug and socket-outlet systems for household and similar purposes for use in South Africa – Part 2 to 2: Fully dedicated system, 16 A 250 V a.c.

S.A.N.S 164 to 3, Plug and socket-outlet systems for household and similar purposes for use in South Africa – Part 3: Conventional system, 6 A 250 V a.c.

S.A.N.S 164 to 4, Plug and socket-outlet systems for household and similar purposes for use in South Africa – Part 4: Dedicated system, 16 A 250 V a.c.

S.A.N.S 164 to 5, Plug and socket-outlet systems for household and similar purposes for use in South Africa – Part 5: Two-pole, non-rewirable plugs, 2.5 A 250 V a.c., with cord, for connection of class 2 equipment.

S.A.N.S 164 to 6, Plug and socket-outlet systems for household and similar purposes for use in South Africa – Part 6: Two-pole systems, 16 A 250 V a.c., for connection of class 2 equipment.

S.A.N.S 337, Plugs and sockets outlets for use in the fixed installation of stoves.

S.A.N.S 529. Heat-resisting wiring cables.

S.A.N.S 556 to 1. Low-voltage switchgear – Part 1: Circuit-breakers.

S.A.N.S 556-2-2. Low-voltage switchgear Part 2 to 2: Earth leakage switches

S.A.N.S 780. Distribution transformers.

S.A.N.S 950, Unplasticized polyvinyl chloride rigid conduit and fittings for use in electrical installations.

S.A.N.S 1012. Electric light dimmers.

S.A.N.S 1019, Standard voltages, currents and insulation levels for electricity supply.

S.A.N.S 1063. Earth rods, couplers and connections.

S.A.N.S 1085. Wall outlet boxes for the enclosure of electrical accessories.

S.A.N.S 1195, Busbars.

S.A.N.S 1213, Mechanical cable glands.

S.A.N.S 1411 to 1, Materials of insulated electric cables and flexible cords—Part 1: Conductors.

S.A.N.S 1418 to 1, Aerial bundled conductor systems – Part 1: Cores.

S.A.N.S 1433 to 1, Electrical terminals and connectors – Part 1: Terminal blocks having screw and screwless terminals.

S.A.N.S 1433 to 2, Electrical terminals and connectors – Part 2: Flat push-on connectors.

S.A.N.S 1507 to 1, Electric cables with extruded solid dielectric insulation for fixed installations (300/500 V to 1 900/3 300 5) – Part 1: General.

S.A.N.S 1507 to 2, Electric cables with extruded solid dielectric insulation for fixed installations (300/500 V to 1 900/3 300 5) – Part 2: Wiring cables.

S.A.N.S 1507 to 3, Electric cables with extruded solid dielectric insulation for fixed installations (300/500 V to 1 900/3 300 5) – Part 3: P.V.C distribution cables.

S.A.N.S 1507 to 4, Electric cables with extruded solid dielectric insulation for fixed installations (300/500 V to 1 900/3 300 5) – Part 4: X.L.P.E distribution cables.

S.A.N.S 1507 to 5, Electric cables with extruded solid dielectric insulation for fixed installations (300/500 V to 1 900/3 300 5) – Part 5: Halogen-free distribution cables.

S.A.N.S 1507 to 6, Electric cables with extruded solid dielectric insulation for fixed installations (300/500 V to 1 900/3 300 5) – Part 6: Service cables.

S.A.N.S 1524 to 1, Electricity payment systems – Part 1: Payment meters.

S.A.N.S 1574 to 3, Electric flexible cables with solid extruded dielectric insulation – Part 3: P.V.C-insulated cables for industrial use.

S.A.N.S 1574 to 5, Electric flexible cables with solid extruded dielectric insulation – Part 5: Rubber-insulated cables for industrial use.

S.A.N.S 1619, Small power distribution units (ready-boards) for single-phase 230 5 service connections.

S.A.N.S 1777. Photoelectric control units for lighting (P.E.C.U's).

S.A.N.S 1799, Watt-hour meters – A.C electronic meters for active energy.

S.A.N.S 1973 to 1, Low-voltage switchgear and controlgear Assemblies – Part 1: Type-tested Assemblies with stated deviations and a rated short-circuit withstand strength above 10 kiloamperes.

S.A.N.S 1973 to 3, Low-voltage switchgear and controlgear Assemblies – Part 3: Safety of Assemblies with a rated prospective short-circuit current of up to and including 10 kiloamperes.

S.A.N.S 1973 to 8, Low-voltage switchgear and controlgear Assemblies – Part 8: Safety of minimally tested Assemblies (M.T.A) with a rated short-circuit current above 10 kiloamperes and a rated busbar current of up to and including 1 600 a.c. and d.c.

S.A.N.S 10086 to 1, The installation, inspection and maintenance of equipment used in explosives atmospheres – Part 1: Installations including surface installations on mines.

S.A.N.S 10089 to 2, The petroleum industry – Part 2: Electrical and other installations in the distribution and marketing sector.

S.A.N.S 10108, The classification of hazardous locations and the selection of equipment for use in such locations.

S.A.N.S 10198 to 4, The selection, handling and installation of electric power cables of rating not exceeding 33 kilovolts – Part 4: Current ratings.

S.A.N.S 10198 to 10, The selection, handling and installation of electric power cables of rating not exceeding 33 kilovolts – Part 10: Jointing and termination of paper-insulated cables.

S.A.N.S 10198 to 11, The selection, handling and installation of electric power cables of rating not exceeding 33 kilovolts – Part 11: Jointing and termination of screened polymeric-insulated cables.

S.A.N.S 10198 to 14, The selection, handling and installation of electric power cables of rating not exceeding 33 kilovolts – Part 14: Installation of aerial bundled conductor (A.B.C) cables.

S.A.N.S 10199. The design and installation of earth electrodes.

S.A.N.S 10222 to 3, Electrical security installations – Part 3: Electric security fences (non-lethal).

S.A.N.S 10292. Earthing of low-voltage (55) distribution systems.

S.A.N.S 10313, Protection against lightning – Physical damage to structures and life hazard.

S.A.N.S 60079 to 0/I.E.C 60079 to 0, Explosive atmospheres – Part 0: Equipment - General requirements.

S.A.N.S 60079 to 1/I.E.C 60079 to 1, Explosive atmospheres – Part 1: Equipment protection by flameproof enclosures "d".

S.A.N.S 60079 to 14/I.E.C 60079 to 14, Explosive atmospheres – Part 14: Electrical installations design, selection and erection.

S.A.N.S 60079 to 17/I.E.C 60079 to 17, Explosive atmospheres Part – 17: Electrical installations inspection and maintenance.

S.A.N.S 60269 to 1/I.E.C 60269 to 1, Low-voltage fuses – Part 1: General requirements.

S.A.N.S 60309 to 1/I.E.C 60309 to 1, Plugs, socket-outlets and couplers for industrial purposes – Part 1: General requirements.

S.A.N.S 60309 to 2/I.E.C 60309 to 2, Plugs, socket-outlets and couplers for industrial purposes – Part 2: Dimensional interchangeability requirements for pin and contact-tube accessories.

S.A.N.S 60364-7-712/I.E.C 60364-7-712, Electrical installations of buildings – Part 7 to 712: Requirements for special installations or locations – Solar photovoltaic (P.V) power supply systems.

S.A.N.S 60439 to 1/I.E.C 60439 to 1, Low-voltage switchgear and controlgear assemblies – Part 1: Type-tested and partially type-tested assemblies.

S.A.N.S 60439 to 2/I.E.C 60439 to 2, Low-voltage switchgear and controlgear assemblies – Part 2: Particular requirements for busbar trunking systems (busways).

S.A.N.S 60439 to 4/I.E.C 60439 to 4, Low-voltage switchgear and controlgear assemblies – Part 4: Particular requirements for assemblies for construction sites (A.C.S).

S.A.N.S 60439 to 5/I.E.C 60439 to 5, Low-voltage switchgear and controlgear assemblies – Part 5: Particular requirements for assemblies for power distribution in public networks.

S.A.N.S 60529/I.E.C 60529, Degrees of protection provided by enclosures (I.P Code).

S.A.N.S 60570/I.E.C 60570, Electrical supply track systems for luminaires.

S.A.N.S 60598-2-18/I.E.C 60598-2-18, Luminaires – Part 2: Particular requirements – Section 18: Luminaires for swimming pools and similar applications.

S.A.N.S 60598-2-23/I.E.C 60598-2-23, Luminaires – Part 2 to 23: Particular requirements – Extra low voltage lighting systems for filament lamps.

S.A.N.S 60669 to 1/I.E.C 60669 to 1, Switches for household and similar fixed-electrical installations – Part 1: General requirements.

S.A.N.S 60669-2-1/I.E.C 60669-2-1, Switches for household and similar fixed electrical installations – Part 2 to 1: Particular requirements – Electronic switches.

S.A.N.S 60730-2-7/I.E.C 60730-2-7, Automatic electrical controls for household and similar use – Part 2 to 7: Particular requirements for timers and time switches.

S.A.N.S 60906 to 3/I.E.C 60906 to 3, I.E.C system of plugs and socket-outlets for household and similar purposes – Part 3: S.E.L.V plugs and socket-outlets, 16 A 6 V, 12 V, 24 V, 48 V, a.c. and d.c.

S.A.N.S 60947 to 2/I.E.C 60947 to 2, Low-voltage switchgear and controlgear – Part 2: Circuit-breakers.

S.A.N.S 60947 to 3/I.E.C 60947 to 3, Low-voltage switchgear and controlgear – Part 3: Switches, disconnectors, switch-disconnectors and fuse-combination units.

S.A.N.S 60947-4-1/I.E.C 60947-4-1, Low-voltage switchgear and controlgear – Part 4 to 1: Contactors and motor-starters – Electromechanical contactors and motor-starters.

S.A.N.S 60947-4-2/I.E.C 60947-4-2, Low-voltage switchgear and controlgear – Part 4 to 2: Contactors and motor-starters – A.C semiconductor motor controllers and starters.

S.A.N.S 60947-4-3/I.E.C 60947-4-3, Low-voltage switchgear and controlgear – Part 4 to 3: Contactors and motor-starters – A.C semi-conductor controllers and contactors for non-motor loads.

S.A.N.S 60947-5-1/I.E.C 60947-5-1, Low-voltage switchgear and controlgear – Part 5 to 1: Control circuit devices and switching elements – Electromechanical control circuit devices.

S.A.N.S 60947-5-2/I.E.C 60947-5-2, Low-voltage switchgear and controlgear – Part 5 to 2: Control circuit devices and switching elements – Proximity switches.

S.A.N.S 60947-5-5/I.E.C 60947-5-5, Low-voltage switchgear and controlgear – Part 5 to 5: Control circuit devices and switching elements – Electrical emergency stop device with mechanical latching function.

S.A.N.S 60947-6-1/I.E.C 60947-6-1, Low-voltage switchgear and controlgear – Part 6 to 1: Multiple function equipment – Transfer switching equipment.

S.A.N.S 60998-2-1/I.E.C 60998-2-1, Connecting devices for low-voltage circuits for household and similar purposes – Part 2 to 1: Particular requirements for connecting devices as separate entities with screw-type clamping units.

S.A.N.S 60998-2-2/I.E.C 60998-2-2, Connecting devices for low-voltage circuits for household and similar purposes – Part 2 to 2: Particular requirements for connecting devices as separate entities with screwless-type clamping units.

S.A.N.S 61000-4-5/I.E.C 61000-4-5, Electromagnetic compatibility (E.M.C) – Part 4 to 5: Testing and measurement techniques – Surge immunity test.

S.A.N.S 61000-4-7/I.E.C 61000-4-7, Electromagnetic compatibility (E.M.C) – Part 4 to 7: Testing and measurement techniques – General guide on harmonics and interharmonics measurements and instrumentation, for power supply systems and equipment connected thereto.

S.A.N.S 61084 to 1/I.E.C 61084 to 1, Cable trunking and ducting systems for electrical installations – Part 1: General requirements.

S.A.N.S 61215/I.E.C 61215, Crystalline silicon terrestrial photovoltaic (P.V) modules – Design qualification and type approval.

S.A.N.S 61238 to 1/I.E.C 61238 to 1, Compression and mechanical connectors for power cables for rated voltages up to 30 kilovolts (U m = 36 kilovolts) – Part 1: Test methods and requirements.

S.A.N.S 61347-2-2/I.E.C 61347-2-2, Lamp controlgear – Part 2 to 2: Particular requirements for d.c. or a.c. supplied electronic step-down convertors for filament lamps.

S.A.N.S 61386 to 1/I.E.C 61386 to 1, Conduit systems for cable management – Part 1: General requirements.

S.A.N.S 61386 to 21/I.E.C 61386 to 21, Conduit systems for cable management – Part 21: Particular requirements – Rigid conduit systems.

S.A.N.S 61386 to 22/I.E.C 61386 to 22, Conduit systems for cable management – Part 22: Particular requirements – Pliable conduit systems.

S.A.N.S 61386 to 23/I.E.C 61386 to 23, Conduit systems for cable management – Part 23: Particular requirements – Flexible conduit systems.

S.A.N.S 61558 to 1/I.E.C 61558 to 1, Safety of power transformers, power supplies, reactors and similar products – Part 1: General requirements and tests.

S.A.N.S 61558-2-2/I.E.C 61558-2-2, Safety of power transformers, power supplies, reactors and similar products – Part 2 to 2: Particular requirements and tests for control transformers and power supplies incorporating control transformers.

S.A.N.S 61558-2-4/I.E.C 61558-2-4, Safety of transformers, reactors, power supply units and similar products for supply voltages up to 1100 V Part - 2 to 4: Particular requirements and tests for isolating transformers and power supply units incorporating isolating transformers.

S.A.N.S 61558-2-5/I.E.C 61558-2-5, Safety of transformers, reactors, power supply units and combinations thereof – Part 2 to 5: Particular requirements and test for transformers for shavers, power supply units for shavers and shaver supply units.

S.A.N.S 61558-2-6/I.E.C 61558-2-6, Safety of transformers, reactors, power supply units and similar products for supply voltages up to 1 100 V – Part 2 to 6: Particular requirements and tests for safety isolating transformers and power supply units incorporating safety isolating transformers.

S.A.N.S 61558-2-15/I.E.C 61558-2-15, Safety of transformers, reactors, power supply units and combinations thereof – Part 2 to 15: Particular requirements and tests for isolating transformers for the supply of medical locations.

S.A.N.S 61643 to 11/I.E.C 61643 to 11, Low-voltage surge protective devices – Part 11: Surge protective devices connected to low-voltage power distribution systems – Requirements and test methods.

S.A.N.S 61643 to 12/I.E.C 61643 to 12, Low-voltage surge protective devices – Part 12: Surge protective devices connected to low-voltage power distribution systems – Selection and application principles.

S.A.N.S 61646, Thin-film terrestrial photovoltaic (P.V) modules – Design qualification and type approval.

S.A.N.S 62040 to 1/I.E.C 62040 to 1, Uninterruptible power systems (U.P.S) – Part 1: General and safety requirements for U.P.S.

S.A.N.S 62053 to 11/I.E.C 62053 to 11, Electricity metering equipment (a.c.) – Particular requirements – Part 11: Electromechanical meters for active energy (classes 0, 5, 1 and 2).

S.A.N.S 62053 to 21/I.E.C 62053 to 21, Electricity metering equipment (a.c.) – Particular requirements – Part 21: Static meters for active energy (classes 1 and 2).

S.A.N.S 62103/I.E.C 62103, Electronic equipment for use in power installations.

S.A.N.S 62305 to 1/I.E.C 62305 to 1, Protection against lightning – Part 1: General principles.

S.A.N.S 62305 to 2/I.E.C 62305 to 2, Protection against lightning – Part 2: Risk management.

S.A.N.S 62305 to 3/I.E.C 62305 to 3, Protection against lightning – Part 3: Physical damage to structures and life hazard.

S.A.N.S 62305 to 4/I.E.C 62305 to 4, Protection against lightning – Part 4: Electrical and electronic systems within structures.

V.C 8003, Compulsory specification for manually operated switches for fixed installations.

V.C 8006, Compulsory specification for safety of flexible cords for electrical appliances.

V.C 8008, Compulsory specification for plugs, socket-outlets and socket-outlet adaptors.

V.C 8035, Compulsory specification for earth leakage protection units.

V.C 8036, Compulsory specification for circuit-breakers.

V.C 8075, Compulsory specification for the safety of electric cables with extruded solid dielectric insulation for fixed installations.

Note 1 Table 4.1 lists the standards applicable in this part of S.A.N.S 10142.

Note 2 When a standard has been amended or replaced, the superseded standard will remain in force.

a) for a period of one year from the date of publication of the amended or substitution standard, or

b) as determined in the amended or substitution standard, or

c) as provided for in a compulsory standard.

3 Definitions

For the purposes of this part of S.A.N.S 10142, the following definitions apply.

3.1

acceptable

acceptable to the regulator

3.2

accessible

not permanently closed in by the structure or surface(s) of the premises

3.3

appliance

3.3.1

class I appliance

appliance that has at least basic insulation throughout, and that is provided with an earthing terminal or earthing contact and is designed (in the case of single phase) for connection by means of a three-core flexible cord

3.3.2

Class 2 Appliance

appliance that has double insulation or reinforced insulation (or both) throughout, and that is without provision for earthing

3.3.3

fixed appliance

appliance that is fastened or otherwise secured at a specific location, and that would require the use of tools to be moved to another location

3.3.4

portable appliance

appliance that is moved in the course of normal operation

3.3.5

stationary appliance

appliance that is normally not moved or cannot easily be moved while in operation

3.4

arm's reach

volume that is limited by the relevant of the following distances measured from a surface expected to be occupied by persons (see annex A):

a) 2.5 m vertically upwards;

b) 1,25 m vertically downwards from the outer edge of the surface;

c) 1,25 m horizontally outwards from the outer edges of the surface; and

d) 0.75 m horizontally inwards from the outer edges of the surface and underneath the surface

3.5

authorized

authorized by the relevant Regulator

3.6

bathroom

room or part of a room that contains a bath, shower or spa (or any combination of these), each installed as a fixture (see figures 7.1.1 to 7.1.5)

3.7

building element

part of a premises such as a wall, floor, ceiling or partition

3.8

cable

3.8.1

armoured cable

cable that has a covering of metallic wires or galvanized steel wires or steeftape as a protection against mechanical damage

3.8.2

flexible cable

cable of which the conductors consist of strands of diameter not exceeding 0.51 millimeters and of which the insulation and covering are such that they afford flexibility and in which the nominal cross-sectional area of each conductor exceeds 4 millimeters

3.8.3

flexible cord cable of which a) the nominal cross-sectional area of each conductor does not exceed 4 millimeters squared , and

b) each conductor consists of strands of diameter less than 0.31 millimeters

3.9

3.8.4

mineral-insulated metal-sheathed cable

cable in which the conductors are insulated by a highly compressed, refractory, mineral insulating material, such as magnesia, and are contained in a solid-drawn hard-metal sheath

3.8.5

multicore cable cable that contains at least two cores

3.8.6

unarmoured metal-sheathed cable

cable that has a sheath of metal to exclude moisture from the conductors and their insulation

Certificate of Compliance

CoC

certificate that is issued by a registered person in respect of an electrical installation or part of an electrical installation

3.10

Chief Inspector

Chief Inspector in terms of the relevant Health and Safety legislation

3.11

circuit

3.11.1

Protected Extra Low Voltage (P.E.L.V) Circuit

extra low voltage (E.L.V) circuit with protective separation from other circuits and which, for functional reasons, may be earthed and/or the exposed conductive parts of which may be earthed

Note 1 P.E.L.V circuits are used where the circuits are earthed and S.E.L.V is not required.

Note 2 See 7.14.2 for additional safety precautions when S.E.L.V and P.E.L.V circuits are used in hazardous locations.

3.11.2

Safety Extra Low Voltage (S.E.L.V) Circuit

extra low voltage (E.L.V) circuit with protective separation from other circuits, and which has no provision for earthing of the circuit or of the exposed conductive parts

3.12

circuit-breaker

mechanical switching device that is capable of making, carrying and breaking currents under normal circuit conditions and of making, carrying for a specified time, and automatically breaking currents under specified abnormal circuit conditions such as those of overcurrent (see also S.A.N.S 556 to 1)

Note See also multipole circuit-breaker (3.50).

3.13

conductive part

3.13.1

exposed conductive part conductive part that a) can easily be touched, and

b) is not a live part under normal conditions, but can become live under fault conditions

3.13.2

extraneous conductive part

conductive part that does not form part of the electrical installation

Note Examples of extraneous conductive parts are a) structural metalwork of a building.

b) items such as heating tubes and non-electrical apparatus electrically connected to them such as radiators and gas-fired or coal-fired cooking appliances, and

c) floors or walls made of conductive material.

3.14

conductor

3.14.1

aerial conductor

conductor that is supported above the ground and that is (or its insulation is) exposed direct to the open air. (see also S.A.N.S 1418 to 1)

3.14.2

bonding conductor

conductor, including any clamp or terminal, that connects together exposed conductive parts (see 3.13.1), extraneous conductive parts (see 3.13.2) or both exposed and extraneous conductive parts, with the object of bringing such parts to the same electrical potential

3.14.3

core

single insulated conductor without protective covering

3.14.4

earth continuity conductor

earthing conductor conductor, including any clamp or terminal, that connects the consumer's earth terminal to the exposed conductive parts of an installation for the purpose of earthing such parts and carrying fault currents

3.14.5

functional bonding conductor

conductor provided for functional equipotential bonding

3.14.6

functional earthing conductor

earthing conductor provided for functional earthing

3.14.7

protective bonding conductor

protective conductor (P.E) provided for protective equipotential bonding

3.14.8

protective conductor

P.E

conductor provided for purposes of safety (protection against electric shock) and that also connects the supply earth to the consumer's earth terminal

3.14.9

protective earth and neutral conductor

P.E.N conductor

conductor that forms part of a supply combining the functions of both protective earthing conductor and neutral conductor. The conductor is also connected to the other earth electrodes and exposed conductive parts of the low-voltage supply

3.14.10

protective earthing conductor

protective conductor provided for protective earthing

3.15

conduit

pipe, usually of diameter not exceeding 50 millimeters, that allows conductors and cables in electrical installations to be drawn in and to be replaced

3.16

consumer

person who is supplied (or who is to be supplied) with electricity by a supplier (see 3.77); or a person who supplies his own electricity

3.17

consumer's earth terminal

terminal that is effectively and permanently earthed and to which the earth continuity conductor of an installation is permanently connected

3.18

contactor

remote-controlled switching device that is capable of making, carrying and breaking currents under normal operating conditions, including overload

3.19

convertor

machine or device for converting one form of electrical power to a different form of electrical power

3.20

cord see flexible cord (3.8.3)

3.21

current

3.21.1

conditional short-circuit current

the value of prospective current, which the equipment (when protected by a short-circuit protective device, as specified by the manufacturer) can withstand for the operating time of the device, under specified test conditions

3.21.2

earth fault current

fault current that flows to earth

3.21.3

earth leakage current

current that flows to earth in an electrically undamaged circuit

3.21.4

fault current

current that results from an insulation failure or from the bridging of insulation

3.21.5

overcurrent

current that exceeds the rated current

Note 1 Depending on its magnitude and duration, an overcurrent might or might not be harmful.

Note 2 In the case of conductors, the current-carrying capacity is deemed to be the rated current.

3.21.6

overload current

overcurrent that occurs in an electrically undamaged circuit

3.21.7

prospective short-circuit current

value of overcurrent at a given point in a circuit, which results from a fault of negligible impedance between live conductors that have a difference of potential under normal operating conditions, or between a live conductor and an exposed conductive part

3.21.8

shock current

current that passes through the body of a person or an animal and that has such a value (depending on frequency, harmonics and duration) that injury is likely to occur

3.21.9

short-circuit current

overcurrent that results from a fault of negligible impedance in a circuit

3.22

discharge lamp

lamp in which light (or radiant energy at a wavelength near that of the visible spectrum) is produced by the passage of an electric current through a vapour or gas

3.23

discharge lighting

lighting that is provided by luminaires in which discharge lamps are used

3.24

disconnector mechanical switching device that a) for reasons of safety, provides, in the open position, an isolating distance in accordance with specified requirements.

b) is capable of opening and closing a circuit either when negligible current is broken or made, or when no significant change in the voltage across the poles of the disconnector occurs, and

c) is capable of carrying currents under normal circuit conditions and of carrying, for a specified time, currents under specified abnormal circuit conditions such as those of short-circuit

Note A disconnector was known as an "off-load isolator".

3.25

distribution board switchboard switchgear and controlgear assembly enclosure that contains electrical equipment for the distribution or control of electrical power from one or more incoming circuits to one or more outgoing circuits

3.26

earthed

so connected to the general mass of earth as to ensure, at all times, an immediate discharge of electrical energy without danger

3.27

earth electrode

one or more conductive parts that are embedded in the earth for the purpose of making effective electrical contact with the general mass of the earth

3.28

earthing arrangement

3.28.1

earthing conductor

conductor, including any clamp or terminal, by which the connection of the consumer's earth terminal or conductor to an earth electrode, or to the supplier's protective conductor, is made

3.28.2

earthing terminal

terminal fitted to equipment or to a device and intended for the electric connection with the earthing arrangement

3.28.3

functional earthing

earthing of a point or points in a system or in an installation or in equipment, which is necessary for purposes other than safety

3.28.4

main earthing terminal

busbar

terminal (or busbar) that is part of the earthing arrangement of an installation that enables the electric connection of a number of conductors for earthing purposes (see also 3.78)

3.28.5

protective earthing

earthing of a point or points in a system or in an installation or in equipment for purposes of safety

3.29

earth leakage protection

form of protection in which an earth leakage unit is used

3.30

earth leakage unit

device that is capable of detecting the flow of a specified or predetermined current from a circuit to earth, and of disconnecting, automatically and reliably, the affected circuit within a specified time when such current exceeds the specified or pre-determined value

3.31

electrical consultant

person who is registered in terms of the Engineering Profession Act, 2000

3.32

electrical equipment

item or any combination of items, including wireways, which is used for the generation, conversion (such as of voltage or frequency), transmission or distribution of electrical energy

3.33

electrical installation

machinery, in or on any premises, that is used for the transmission of electrical energy from a point of control (see 3.56) to a point of consumption (see 3.55) anywhere on the premises, including any article that forms part of such an installation, irrespective of whether or not it is part of the electrical circuit, but excluding a) any machinery of the supplier that is related to the supply of electricity on the premises,

b) any machinery that is used for the transmission of electricity of which the voltage does not exceed 50 V, where such electricity is not derived from the main supply of a supplier, and

c) any machinery that transmits electrical energy in telecommunication, television or radio circuits

3.34

electrode water heater

device that is designed to heat water or other liquid by passing electricity between electrodes immersed in the water or liquid. The device may convert water to steam

Note A resistor that is in contact with liquid is, in effect, an electrode.

3.35

enclosure

part that provides protection of equipment against certain external influences and, in any direction, protection against direct contact

3.36

equipotential bonding

3.36.1

equipotential bonding terminal

terminal fitted to equipment or to a device and intended for the electric connection with the equipotential bonding system

3.36.2

functional equipotential bonding

equipotential bonding for purposes other than safety

3.36.3

protective equipotential bonding equipotential bonding for purposes of safety

3.37

fault free

arrangement of conductors for which, under normal operating conditions, the occurrence of a short-circuit fault between phases or between phases and earth is only a remote possibility

3.38

fire officer

officer (or any person to whom such power has been duly delegated) who is appointed by a local authority to administer its bylaws (and any relevant statutory regulations) relating to fire protection

3.39

flammable

descriptive of a material that, when heated for 5 min in an oven at 300 °C (in the manner set out in an appropriate standard such as S.A.N.S 556 to 1), is capable of burning or of giving off vapours in sufficient quantity to ignite at a pilot flame

3.40

flexible conduit

tubing that is intended to house and to protect electric wiring and that is so designed that it is flexible

3.41

flexible cord see 3.9.3

3.42

fuse

device that, by the melting of one or more of its specifically designed and dimensioned elements, opens the circuit in which it is inserted if the current that flows through it exceeds the rated current for a specified time (see also S.A.N.S 60269 to 1)

Note A fuse comprises all the parts that form the complete device.

3.43

hazardous location

location in which fire or explosion may occur owing to the presence of gases, vapours, dusts or fibres that, in the presence of air and in certain concentrations, are flammable or explosive

Note See S.A.N.S 10108 for the classification of hazardous locations.

3.44

insulation

3.44.1

basic insulation

insulation applied to live parts to provide basic protection against electric shock

Note Basic insulation does not include insulation used for functional purposes, for example, wire enamel.

3.44.2

double insulation

insulation that comprises both basic insulation and supplementary insulation. Usually indicated by the symbol ☐

3.44.3

reinforced insulation

single insulation system applied to live parts, which provides a degree of protection against electric shock equivalent to double insulation

Note The term "insulation system" does not imply that the insulation is one homo-jee-nee-us piece. It may comprise several layers that cannot be tested singly as supplementary or basic insulation.

3.44.4

supplementary insulation

independent insulation applied in addition to basic insulation in order to provide protection against electric shock in the event of failure of the basic insulation

3.45

lighting system

3.45.1

emergency lighting

system that provides sufficient illumination to replace the existing safety and normal lighting system in the event of a power failure, so that people can evacuate a place of assembly

3.45.2

normal lighting

system that provides general illumination but does not necessarily provide illumination of exit routes

3.45.3

safety lighting

system that provides sufficient illumination to allow all the occupants of a place of assembly to see clearly enough during a performance to move around or to leave. Such a system includes illuminated exit signs that indicate the exit routes for all the occupants of a place of assembly (including areas such as projector rooms, control rooms and orchestra pits)

3.46

live alive at an electrical potential to earth

Note Live parts include the neutral conductor and conductive parts connected to it.

3.47

local authority

municipal council, borough council, town council, village council, village management board, town board, health board or any such institution

3.48

luminaire

appliance that distributes, filters or transforms the light transmitted from one or more lamps and that includes all the parts necessary for supporting, fixing and protecting the lamps but not the lamps themselves, and, when necessary, circuit auxiliaries together with the means for connecting them to the supply

Note A batten lamp holder or a lamp holder suspended by a flexible cord is a luminaire.

3.49

marina

fixed wharf, jetty, pier or floating pontoon arrangement capable of berthing or mooring more than one pleasure craft

3.50

multipole circuit-breaker

circuit-breaker in which all poles are mechanically connected together and that is suitable for making, carrying and breaking the currents in all the phase conductors or, if so required, in all the live conductors of a circuit

3.51

new

innovative descriptive of a technique or item of equipment for use in an electrical installation where such technique or item of equipment does not fall within the scope of a standard (see 3.75).

3.52

overcurrent protection (of a circuit)

means of interrupting the current in a circuit when that current exceeds its rated value

Note See 6.10.1 for the use of fuses not being permitted as overcurrent protection in residential installations. 3.53

place of assembly

theatre, cinema, church and any other place where people gather and where natural lighting is inadequate to allow for safe evacuation

Note Adjacent areas are treated as separate places of assembly.

3.54

plug device that a) has two or more metallic contacts in the form of pins.

b) is arranged for attachment to a flexible cord or cable, and

c) is intended for engagement with a socket-outlet (see 3.72)

3.55

point of consumption

point of outlet, or the supply terminal of machinery that is not connected to a point of outlet and that converts electrical energy to another form of energy, provided that in the case of machinery that has been installed for any specific purpose as a complete unit, the point of consumption is the supply terminals that have been provided on the unit of machinery for that purpose

3.56

point of control

point at which a consumer can, on or in any premises, switch off the electrical installation from the electricity supplied from the point of supply

3.57

point of outlet

termination of an electrical installation, which has been provided for connecting any electrical machinery without the use of a tool, provided that no connection to a busbar is deemed to be a point of outlet (see socket-outlet, 3.72)

3.58

point of supply

point at which a supplier supplies electricity to any premises

3.59

pole

portion of a switching device associated exclusively with one electrically separated conducting path of its main circuit and excluding those portions that provide a means for mounting and operating all poles together

Note A switching device is called single pole if it has only one pole. If it has more than one pole, it may be called multipole (two pole, three pole, etcetera), provided that the poles are or can be coupled in such a manner as to operate together.

3.60

portable water pump

pump that can be easily moved from one place to another while connected to the supply

3.61

premises

place such as a site, building or structure, whether stationary or mobile, that can be electrically wired

3.62

protected socket-outlet

socket-outlet combined with, or adjacent to and protected by, a device that has either overload protection or overcurrent protection

3.63

protective device

unit that comprises one or more fuses or circuit-breakers

3.64

protective screening

separation from live parts by means of an interposed conductive screen, connected to earth by means of an external protective conductor

3.65

protective separation

separation between circuits by means of basic and supplementary protection (basic insulation plus supplementary insulation or protective screening) or by provision of equivalent protection (for example, reinforced insulation)

3.66

residential installation

electrical installation in a private dwelling or in an individual dwelling unit, including installations in flats, hotels, boarding houses or other residential institutions

3.67

safety supply

supply of electricity that is obtained from a) the unearthed secondary circuit of an isolating transformer with limited output voltage, specified by the manufacturer, or

b) any other isolating device that provides equivalent safety and the same degree of separation between the primary and secondary circuits, or

c) an isolated generator or a battery that provides a non-earthed supply

3.68

sauna

enclosure in which heat is generated for therapeutic or recreational purposes and that is designed to accommodate one or more persons

3.69

series-connected system

cascaded system protection system that allows for the installation of circuit-breakers that cannot necessarily be rated to handle the full prospective short-circuit current at their point of installation, provided that they are backed up by another fully rated circuit-breaker in a predetermined and tested coordination

3.70

shaver supply unit

accessory that embodies an isolating transformer with limited output and one or more socket-outlets that allow the use of only one plug at a time

3.71

short-circuit protective device

S.C.P.D

device intended to protect a circuit or parts of a circuit against short-circuit currents by interrupting the current

3.72

socket-outlet device that a) has two or more metallic spring contacts designed to accept the corresponding pins of a plug (see 3.54), b) is designed for fixing onto or into a building element (see 3.7) or other flat surface, and c) is arranged for connection to the wiring of an installation

Note Single-phase socket-outlets that are rated in accordance with S.A.N.S 164 to 6 are used in residential and similar installations may be regarded as equivalent for the purposes of this part of S.A.N.S 10142 but, because it is intended that the standard rating will in due course be 16 A only, the use of socket-outlets rated at any value other than 16 A is not recommended, with the exception of two-contact socket-outlets (see 3.57).

3.73

spa

container a) in which water may be heated electrically or agitated electromechanically, or both,

b) that is designed to accommodate at least one person, and

c) the electrical equipment of which is permanently connected to the electricity supply

3.74

specialized electrical installation

electrical installation such as in a) a hazardous location, as described in S.A.N.S 10108.

b) an explosive atmosphere, as described in S.A.N.S 10086 to 1.

c) the petroleum industry, as described in S.A.N.S 10089 to 2, and

d) a medical location, as described in 7.7 of this part of S.A.N.S 10142

3.75

standard

applicable compulsory standard or an applicable standard published by Standards South Africa, or by another standards body whose standards have been referred to in this part of S.A.N.S 10142

3.76

stove coupler

stove connection that complies with the requirements of S.A.N.S 60309 to 1, and of the dimensions as given in S.A.N.S 337

3.77

supplier

in relation to a particular installation, any local authority (see 3.47), statutory body or person who supplies, contracts or agrees to supply, electricity to that electrical installation

3.78

supply earth terminal

clamp or terminal at the point of supply to which the supply protective conductor is connected (see 3.28)

3.79

switch

Note A switch may also be capable of making, but not breaking, short-circuit currents.

3.79.1

multipole switch

switch in which all poles are mechanically coupled together and that is suitable for making, carrying and breaking the currents in all the phase conductors or, if so required, all the live conductors of a circuit

3.79.2

switch-disconnector

switch that, in the open position, satisfies the isolating requirements specified for a disconnector

Note A switch-disconnector was known as an "on-load isolator".

3.80

terminal

device in or on which conductors can be terminated and that provides substantial electrical connections and supports the terminations sturdily and safely, with a suitable cover, if necessary, to render it safe (see also S.A.N.S 1433 to 1 and S.A.N.S 1433 to 2)

3.81

test report

report (see 8.7) that is issued by a registered person in respect of an electrical installation or part of an electrical installation

3.82

touch voltage

U

voltage which, during an insulation fault, appears between simultaneously accessible parts

Note By convention, the term is used only in connection with protection against indirect contact.

3.83

transformers

3.83.1

class I transformer

transformer in which protection against electric shock does not rely on basic insulation only, but which includes an additional safety precaution in such a way that means, such as an earthing terminal, are provided for the connection of accessible conductive parts to the protective earthing conductor in the fixed wiring of the installation, so that accessible conductive parts cannot become live in the event of failure of the basic insulation.

Note A class I transformer may have parts with double or reinforced insulation.

3.83.2

Class 2 Transformer

transformer in which protection against electric shock does not rely on basic insulation only, but in which additional safety precautions such as double insulation or reinforced insulation are provided, there being no provision for protective earthing or reliance upon installation conditions

3.83.3

isolating transformer

transformer with protective separation between the input and output windings, which are electrically separated in order to limit hazards due to accidental simultaneous contact with earth and live parts or with earth and metal parts that can become live in the event of an insulation fault

Note A class 2 isolating transformer has additional safety precautions such as double insulation or reinforced insulation and has no provision for earthing.

3.83.4

safety isolating transformer

3.84

isolating transformer designed to supply safety extra low voltage (S.E.L.V) or protected extra low voltage (P.E.L.V) circuits

voltage

3.84.1

extra low voltage

E.L.V

voltage that does not exceed 50 V a.c. or 120 V d.c.

3.84.2

safety extra low voltage

S.E.L.V

voltage that does not exceed 50 V a.c. or 120 V ripple-free d.c. between conductors, or between any conductor and earth, in a circuit which is isolated from the supply mains by means such as a safety isolating transformer

Note 1 Maximum voltage lower than 50 V a.c. or 120 V ripple-free d.c. may be specified in particular requirements, especially when direct contact with live parts is allowed.

Note 2 The voltage limit should not be exceeded at any load between full load and no load when the source is a safety isolating transformer.

Note 3 "Ripple-free" is conventionally defined as an r.m.s. ripple voltage that does not exceed 10 % of the d.c. component; the maximum peak value does not exceed 140 V for a nominal 120 V ripple-free d.c. system and 70 V for a nominal 60 V ripple-free d.c. system.

3.84.3

low voltage

L.V voltage that does not exceed 1 000 V a.c. or 1 500 V d.c, including E.L.V

3.85

wireway

Note A wireway can consist of one or more separate wireway channels, each of which is intended for different services such as installation wiring and telecommunication wiring.

3.85.1

conduit see 3.15

3.85.2

ducting

closed enclosure that allows insulated conductors and cables in electrical installations to be drawn in and to be replaced.

3.85.3

flexible conduit see 3.40

3.85.4

trunking

closed enclosure that comprises a base with a removable cover that is intended to completely surround insulated conductors and cables in electrical installations and accommodate other electrical equipment, for example, in the case of power skirting

4 Compliance

4.1 Applicable standards

4.1.1 Table 4.1 gives a list of commodities and the applicable standards. The commodities given in column 1 shall comply with the applicable standards given in column 3.

4.1.2 Each component used in a d.c. installation shall comply with the requirements for d.c. operation stipulated in the relevant standard.

4.2 Notices, labels and rating plates

Any notices, labels or rating plates that are required in terms of this part of S.A.N.S 10142 shall be durable and not removable except by determined and deliberate action. The inscriptions shall be legible and indelible. Details on the topics given in column 2 of table 4.2 can be found in the relevant subclauses in column 1.

Table 4.2 summary: A detailed list of regulatory notices, labels, and rating plates mapped to specific subclauses. These requirements cover a wide range of electrical installations, including distribution board labels for incoming and outgoing circuits in subclause 6.6.1.20, warning labels on distribution boards in subclause 6.6.1.21, and high-voltage signs in subclause 7.13.3.2. Other examples include requirements for identifying ring circuits in subclause 6.6.1.13, marking load and line on circuit-breakers in subclause 6.8.2.3(b), and specifications for the fireman's switch in subclause 7.13.10.5(g), (h).

5 Fundamental requirements

5.1 General

All commodities in an electrical installation shall be installed in accordance with the requirements in this part of S.A.N.S 10142 and with the manufacturer's instructions, where applicable.

Note 1 This clause contains the general safety principles applicable to electrical installations.

Note 2 The manufacturer's instructions may contain more stringent requirements.

5.2 Safety

5.2.1 Live parts

It shall not be possible to touch any live part within arm's reach with the standard test finger (see S.A.N.S 60529)

a) during normal operation, or

b) when a cover is removed, unless the cover is removed with the use of a tool or a key.

5.2.2 Temperature

5.2.2.1 Unless otherwise permitted by an applicable standard (see 4.1 and table 4.1), electrical equipment shall be so designed, positioned and protected that accessible parts under normal operating conditions do not reach a temperature (safe touch temperature) that exceeds a) 70 degrees Celsius in the case of metallic parts, and

b) 90 degrees Celsius in the case of non-metallic parts.

5.2.2.2 If electrical equipment has to be mounted in a fire risk area or adjacent to flammable material, the equipment shall be a) of, or enclosed by, thermally non-conductive non-flammable material, or

b) so designed or positioned (or both) that the flammable material is not subjected to any hazardous heating, or

c) so designed or positioned (or both) that any arc or sparks are contained within the enclosure.

5.2.3 Earth fault current protection

5.2.3.1 A new electrical installation shall not be connected to the supply unless the supply includes a protective conductor. (See also 6.11 and 8.5.3.)

5.2.3.2 People, animals and property shall be protected against harmful earth fault currents by protective measures such as a) earthing and bonding.

b) electrical separation of circuits.

Note The expression "electrical separation of a circuit" means that the circuit is electrically isolated from other circuits in an installation. If an electrically separate circuit is short and is well protected against damage (for example, as in a shaver unit), it is unlikely that there will be faults on the circuit. However, if the circuit is long, the risk of one conductor faulting to earth increases. One fault will reduce the effectiveness of "electrical separation of a circuit" as a protective measure; a second fault can be dangerous. To be able to rely on "electrical separation of a circuit" as a protective measure for a long circuit, a specially designed device should be used to monitor the circuit, and, if a fault occurs, the device should disconnect the circuit or give an audible or a visible warning of the fault.

c) the use of an isolating transformer with an output of 50 V or less.

d) the use of electrical equipment that is double insulated, or

Note Electrical equipment that complies with an applicable standard (see 4.1 and table 4.1) and that bears the symbol ☐ is deemed to be double insulated.

e) the use of earth leakage protection for socket-outlet circuits.

5.2.3.3. The rated earth leakage tripping current (rated residual current) I Delta n required to activate an earth leakage protection device shall not exceed 30 milliamperes.

5.2.3.4 Earth leakage protection shall not be used as an alternative protective measure to those given in 5.2.3.2(a) and 5.2.3.2(b). Earth leakage protection shall be considered an additional protective measure. (see also 6.7.5.)

5.2.3.5 The protective measures described in 5.2.3.2(a) to 5.2.3.2(e) may be applied to a a) complete installation.

b) part of an installation.

c) circuit, or

d) locality.

No protective measure shall interfere with the operation of any other protective measure.

5.2.4 Positioning of equipment

Electrical equipment which, under normal conditions will be a) exposed to flammable or explosive gas, vapour, dust or liquid, or to external influences such as direct sunlight, corrosive vapour or oil, or

b) in a hazardous location.

shall be so selected or enclosed that it is protected against harmful effects or it shall comply with the requirements of an applicable standard (or both).

5.2.5 Marking of equipment

All equipment and circuits shall be labelled as required by this part of S.A.N.S 10142. (See also 4.2.).

5.3 Basic provisions

5.3.1 Estimated load

The load of an installation shall be estimated to determine the type and capacity of the required electricity supply.

Note 1 Annex C gives an example of estimating the load for residential installations but the method is not to be regarded as an exact method.

Note 2 The supplier may have special requirements for large installations and for installations that need special consideration.

5.3.2 Voltage drop

5.3.2.1 When all conductors of an a.c. installation are carrying their maximum estimated load, the difference in voltage (the voltage drop) between the point of supply and any point of outlet or terminals of fixed appliances shall not exceed 5% of the standard voltage or of the declared phase-to-neutral voltage (see also 6.2.7). In the case where reticulation is part of the electrical installation after the point of supply, the 5% voltage drop shall be calculated to include the reticulation part of the installation (for example, in the case of a housing scheme where further submetering with a further point of control is installed for individual consumers).

5.3.2.2 When all conductors of a d.c. installation are carrying their maximum estimated load, the difference in voltage (the voltage drop) between any point of supply and any point of consumption shall not exceed 5% of the circuit nominal voltage or as determined by the specific equipment requirements.

5.3.3 Nominal cross-sectional area of conductors

The nominal cross-sectional area of a conductor shall be determined in accordance with the following safety considerations:

a) the conductor's maximum permissible continuous temperature;

b) the permissible voltage drop of an installation:

c) the electromechanical stresses and thermal effects that are likely to occur as a result of short-circuits;

d) the maximum impedance of the conductor with respect to the functioning of the short-circuit protection; and

e) mechanical stresses.

Note Nominal cross-sectional areas exceeding those necessary for safety may be required for practical operation.

5.3.4 Type of wiring and methods of installation

The type of wiring and methods of installation shall be determined after consideration of the following:

a) the location (also consider intentional or inadvertent damage);

b) the nature of the building elements for supporting the wiring;

c) the accessibility of the wiring to persons and livestock;

d) the voltage;

e) the electromechanical stresses and thermal effects likely to occur as a result of short-circuits; and

f) stresses imposed on the wiring during installation and in service.

5.3.5 Protective equipment

Protective devices shall operate at currents and voltages and within periods of time that are related to the characteristics of the circuit that they serve. The type of protective device needed shall be determined in accordance with its respective function, that is to protect the circuit against one or more of the following:

a) overcurrent:

1) overload current; and

2) short-circuit current:

b) single phasing;

c) earth fault current:

d) overvoltage;

e) undervoltage:

f) incorrect phase rotation; and

g) fire risk.

5.3.6 Emergency control

If, in dangerous situations, it is necessary to immediately interrupt the power supply, the interrupting device or devices in case of mains and alternative supplies, shall be installed such that all the devices shall a) easily be recognized, and

b) effectively and quickly operated.

5.3.7 Disconnecting devices

An installation shall have disconnecting devices that allow the installation to be disconnected for maintenance, testing, fault detection or repair. In the case of circuits or items of equipment, additional disconnecting devices could be required to allow disconnection for maintenance, testing, fault detection or repair of such circuits or equipment.

5.3.8 Positioning and accessibility of electrical equipment

Electrical equipment shall be so positioned that a) it does not impair the functioning or safety of other equipment.

b) it is readily accessible for installation, replacement, operation, testing, inspection, maintenance and repair (see 6.6.1.9 and 6.9.4 for the main switch). All parts of the installation shall be accessible without the need to enter any adjoining premises (for example, in an apartment building),

Note Common areas (such as passages and entrance halls) are not regarded as adjoining areas.

c) there is easy access to its location.

d) it is not likely to be physically damaged.

e) dust or moisture is not likely to accumulate on live or other parts and cause flashover, and

f) where the distribution board is concealed by a cupboard or other covering, the notice for live electrical apparatus referred to in annex N shall be in a conspicuous place indicating the position of the distribution board.

5.4 Characteristics

5.4.1 General

The characteristics of the selected equipment shall be appropriate to the conditions and parameters on which the design of an installation is based.

5.4.2 Voltage

The equipment shall be suitable for operation on the maximum steady (r.m.s.) voltage and overvoltage to which it is likely to be subjected. Equipment shall be rated in accordance with the intended application for use on one of the following voltages used in South Africa:

a) A.C. circuits:

1) standard voltages of

1) 230 V single-phase, 2) 230/400 V three-phase four-wire, and

a tolerance of plus or minus 10 percent on these voltages.

Note For certain equipment it may be necessary to consider the lowest voltage that is likely to occur.

2) declared voltages of 525 V three-phase three-wire is a commonly used voltage and the tolerance is plus or minus 5% .

Note Declared voltage is the voltage declared by the manufacturer up to the maximum of 1 000 V.

b) D.C. circuits:

1) preferred voltages of 1) 12 V, 2) 24 V, 3) 48 V,

2) other voltages of 1) 60 V, 2) 80 V, 3) 110 V, 4) 220 V, 5) 250 V, 6) 500 V, and

the tolerances on the above d.c. voltages are determined by the application.

c) Voltages on control circuits should preferably not exceed 230 V a.c. or 110 V d.c.

5.4.3 Current

The equipment shall be suitable for operation at the maximum steady (r.m.s.) current to which it is likely to be subjected. It shall also be able to carry the current that is likely to flow under abnormal conditions and for the period that the current is likely to flow.

Note The period that an abnormal current will flow is equal to the operating time of any protective device.

5.4.4 Frequency

If the operation of the equipment is sensitive to frequency variations, the rated frequency of the equipment shall be such that the equipment operates safely when it is subjected to the frequency variations that are likely to occur in the circuit.

5.4.5 Power

If the equipment is selected on the basis of its power characteristics, it shall be suitable for the duty demanded of it.

5.5 Prevention of harmful effects

5.5.1 Prevention of mutually detrimental influence

An electrical installation shall be so arranged that there is minimal mutually detrimental influence between it and any other installation (including non-electrical installations) on the premises.

5.5.2 Harmful effects by electrical equipment

Electrical equipment shall be so designed and arranged that any damage as a result of a fault be localized as much as possible. The equipment shall not have harmful effects on other equipment or on the power supply during normal service (including switching operations). Factors that can lead to harmful effects include a) the power factor,

b) inrush current.

c) asymmetrical load, and

d) harmonics.

5.5.3 Surge protection

Where a surge protection device is installed, it shall be installed after the main switch (see annex 1).

5.6 Environmental conditions

5.6.1 Electrical equipment shall be able to withstand the environmental conditions of the location in which it is installed. However, electrical equipment may be protected to allow its use in a particular environment for which it is not designed, provided that the environment shall allow for the normal heating and cooling of the equipment.

5.6.2 This part of S.A.N.S 10142 applies to electrical installations located at altitudes not exceeding 2 000 m. In the absence of specific product information with regard to application at high altitudes, products should be derated as follows:

a) 1% of the thermal current rating for every 500 m, or part thereof, exceeding an altitude of 2 000 m;

b) 1% of the maximum voltage rating for every 100 m, or part thereof, exceeding an altitude of 2 000 m.

5.7 Medical locations

In medical locations it is necessary to ensure the safety of patients who could be subject to the application of medical electrical equipment. For every activity and function in a medical location, the particular requirements for safety have to be considered. In the majority of cases, safety can be achieved by ensuring the safety of the installation. The use of medical electrical equipment on patients while under intensive care (of clinical importance) has called for enhanced reliability and safety of electrical installations in hospitals by improving the safety and continuity of supplies (see 7.7).

5.8 Extra Low Voltage Systems (S.E.L.V and P.E.L.V)

5.8.1 Shock hazard protection by extra low voltage

5.8.1.1 Protection by extra low voltage is a protective measure that consists of the following two different extra low voltage systems:

a) S.E.L.V (safety extra low voltage), an unearthed system; and

b) P.E.L.V (protected extra low voltage), an earthed system.

5.8.1.2 The use of a S.E.L.V or P.E.L.V system is considered as a protective measure in all situations and the protection is provided by a) the limitation of the voltage in the system to 50 V a.c. r.m.s. or 120 V ripple-free d.c.,

b) protective separation of the S.E.L.V or the P.E.L.V system from all circuits other than S.E.L.V and P.E.L.V circuits, and basic insulation between the S.E.L.V or the P.E.L.V system and other S.E.L.V or P.E.L.V systems, and

c) basic insulation between the S.E.L.V system and earth for the S.E.L.V systems only

Note 1 Typical applications are E.L.V lighting and emergency buttons in a bathroom.

Note 2 Additional safety precautions are required when S.E.L.V and P.E.L.V circuits are used in hazardous locations (see 7.14.2).

5.8.2 Requirements for basic protection and fault protection

5.8.2.1 Basic protection and fault protection are deemed to be provided when a) the nominal voltage cannot exceed the upper limit of 50 V a.c. or 120 V d.c.,

b) the source of supply is one of the sources listed in 5.8.3, and

c) the conditions of 5.8.4 are fulfilled.

5.8.2.2 If the system is supplied from a higher voltage system by equipment which does not provide at least simple separation between that system and the extra low voltage system, such as in auto-transformers, potentiometers, semiconductor devices, etcetera, the output circuit is deemed to be an extension of the input circuit and shall be protected by the protective measure applied to the input circuit.

Note In a d.c. system with batteries, the battery charging and floating voltages exceed the battery nominal voltage, depending on the type of battery. This does not require any protective provisions in addition to those specified in this clause. The charging voltage would normally not exceed a maximum value of 75 V a.c. or 150 V d.c.

5.8.3 Sources for S.E.L.V and P.E.L.V

5.8.3.1 General sources

General sources that provide S.E.L.V and P.E.L.V are the following:

a) safety isolating transformers that comply with the requirements of S.A.N.S 61558-2-6;

b) sources that provide a degree of safety equivalent to that of the safety isolating transformer specified in (a) (for example, a motor generator with windings that provide equivalent isolation);

c) electrochemical sources (for example, a battery) or other sources independent of a higher voltage circuit (for example, a diesel-driven generator); and

d) certain electronic devices that comply with appropriate standards where provisions have been taken to ensure that, even in the case of an internal fault, the voltages at the outgoing terminals cannot exceed the values specified in 5.8.2. Higher voltages at the outgoing terminals are, however, permitted if it is ensured that, in the case of contact with a live part or in the event of a fault between a live part and an exposed conductive part, the voltages at the output terminals are immediately reduced to the values in 5.8.2 or less.

Note 1 Examples of such electronic devices include insulation testing equipment.

Note 2 Where higher voltages exist at the outgoing terminals, compliance with this clause may be assumed if the voltages at the outgoing terminals are within the limits specified in 5.8.2 when measured with a voltmeter that has an internal resistance of at least 3 000 Ω.

5.8.3.2 Mobile sources

Mobile sources that provide S.E.L.V and P.E.L.V, for example, safety isolating transformers or motor generators, shall be selected or erected in accordance with the requirements for protection by using double or reinforced insulation.

5.8.4 Requirements for S.E.L.V and P.E.L.V Circuits

5.8.4.1 S.E.L.V and P.E.L.V circuits shall have

a) protective separation of live parts from the live parts of other circuits (except for other S.E.L.V and P.E.L.V circuits), which shall be provided by

1) double insulation, or

2) reinforced insulation for the highest voltage present, or

3) basic insulation and protective screening according to the highest voltage present, and

b) basic insulation between live parts and the live parts of other S.E.L.V or P.E.L.V circuits.

5.8.4.2 S.E.L.V circuits shall have basic insulation between live parts and earth not less than that provided between the input and the output windings of a safety isolating transformer.

Note The earthing of P.E.L.V circuits can be achieved by an appropriate connection to earth within the source itself.

5.8.4.3 Protective separation of the wiring systems of S.E.L.V and P.E.L.V circuits from the live parts of other circuits can be achieved by one of the following arrangements:

a) S.E.L.V and P.E.L.V circuit conductors shall be enclosed in a non-metallic sheath or non-metallic enclosure in addition to basic insulation; or

b) S.E.L.V and P.E.L.V circuit conductors shall be separated from conductors of circuits at different voltages by an earthed metallic sheath or earthed metallic screen; or

c) circuits at different voltages can be contained in a multiconductor cable or other grouping of conductors if the S.E.L.V and P.E.L.V conductors are insulated for the highest voltage present.

5.8.4.4 Plugs and socket-outlets for S.E.L.V and P.E.L.V systems shall comply with the following requirements:

a) plugs shall not be able to enter socket-outlets of other voltage systems;

b) socket-outlets shall not admit plugs of other voltage systems; and

c) socket-outlets in S.E.L.V systems shall not have a protective conductor.

5.8.4.5 Live parts of S.E.L.V circuits shall not be connected to a) earth, or

b) live parts that form part of other circuits, or

c) protective conductors that form part of other circuits.

5.8.4.6 Exposed Conductive Parts of S.E.L.V Circuits Shall Not Be Connected To

a) earth, or

b) protective conductors, or

c) exposed conductive parts of another circuit.

Note If the exposed conductive parts of S.E.L.V circuits are liable to come into contact, either fortuitously or intentionally, with the exposed conductive parts of other circuits, protection against electric shock no longer depends solely on protection by S.E.L.V, but also on the protective provisions to which the latter exposed conductive parts are subject.

5.8.4.7 If the nominal voltage exceeds 25 V a.c. r.m.s. or 60 V ripple-free d.c. or if the equipment is immersed in a conductive liquid, basic protection shall be provided for S.E.L.V and P.E.L.V circuits by a) insulation, or

b) barriers, or

c) enclosures.

5.8.4.8 If the nominal voltage does not exceed 25 V a.c. r.m.s. or 60 V ripple-free d.c.

a) for S.E.L.V circuits, basic protection is generally not necessary under normal dry conditions, and

b) for P.E.L.V circuits, the exposed conductive parts or the live parts or both are connected by a protective conductor to the main earthing terminal.

5.8.4.9 If the nominal voltage of the S.E.L.V or P.E.L.V system does not exceed 12 V a.c. r.m.s or 30 V ripple-free d.c., basic protection in all other cases is not necessary.

Note "Ripple-free" is conventionally defined for sinusoidal ripple voltage as a ripple content of not more than 10 % r.m.s.: the maximum peak value does not exceed 140 V for a nominal 120 V ripple-free d.c. system and 70 V for a nominal 60 V ripple-free d.c. system.

6 Installation requirements

6.1 General circuit arrangements

6.1.1 In a multiphase installation, the circuits shall be so arranged that the total load is, as nearly as is practicable, balanced between the phases of the supply.

6.1.2 A three-phase four-wire circuit that supplies only single-phase items of electrical equipment (that are connected between a phase conductor and the neutral conductor) may supply any number of points if a) the circuit is protected by

1) a multipole circuit-breaker, or

2) single-phase protective devices with a multipole switch-disconnector on the supply side,

b) throughout the circuit, the neutral conductor has the same nominal cross-sectional area as the associated phase conductors.

c) tee-joints are accessible and the main neutral conductor remains unbroken when tee-joints are removed, and

d) the total load is, as nearly as is practicable, balanced over the three phases.

6.1.3 Where it is required to separately control a part of an installation (such as fire services or emergency equipment), it shall be supplied by a separate dedicated circuit.

6.1.4 All the conductors of any circuit shall originate at the same distribution board.

6.1.5 A maximum of three conductors may be connected to any one terminal provided that the terminal has the correct rating.

6.1.6 The neutral conductor shall not be connected direct to earth or to the earth continuity conductor on the load side of the point of control except as allowed in 7.16.4.

6.1.7 If conductors that operate at different voltages run in the same wireway, the insulation of each conductor shall be able to withstand the highest conductor voltage in the wireway. Alternatively, the conductors shall be separated by a continuous barrier of insulating material or earthed metal.

6.1.8 If a luminaire is used as a wireway (through-wiring), a) there shall be a heat-resistant barrier between the ballast or transformer and the conductor; or

b) heat-resistant cable that complies with S.A.N.S 529 shall be used.

6.1.9 The continuity of neutral and earth circuits shall be ensured at all times, and, except where the luminaire is used as a wireway for through-wiring, the continuity shall not be disturbed during repair, replacement or removal of any appliance.

6.1.10 Conductors that form part of a d.c. installation shall not be run in the same wireway as conductors that form part of an a.c. installation.

6.1.11 Flexible cords shall not be used as part of the electrical installation, except where a) required by the relevant product solely for termination or connection of moving parts.

b) specified in the product standard.

c) used as single cores in conduits.

d) used in an authorized wiring system (see 3.5), or

e) needed for the connection of luminaires, provided that each connection is limited to one luminaire and to a maximum length of 3 m.

6.1.12 Where flexible cords are used, the strands of the conductors shall be protected to prevent the strands from being cut off in terminations.

6.2 Current-carrying capacity of conductors and cables

6.2.1 General applications

Note The required size of conductor is determined by considering the required current-carrying capacity of the cable, the permitted voltage drop, requirements for overcurrent protection and short-time overcurrent rating.

6.2.1.1 The nominal cross-sectional area of the conductors of a cable shall be such that the maximum estimated load to be carried by the conductors does not exceed their current-carrying capacity.

6.2.1.2 The current-carrying capacity of each conductor in a circuit that comes from a distribution board shall be the same at each point in the circuit, but if the conductors of lowest current-carrying capacity are protected against overcurrent in accordance with 6.2.1.1, a) the current-carrying capacity of conductors at one or more points in the circuit may be reduced;

b) one or more spurs that have conductors of reduced current-carrying capacity may be teed into a circuit; and

c) at one point only, a circuit may be split into two or more branches, each having conductors of reduced current-carrying capacity.

6.2.1.3 Except in the case of a ring circuit, there shall be no branches, tee-offs or socket-outlets along parallel conductors and, where two or more conductors are connected in parallel, the conductors shall a) have the same characteristics in respect of conductor material, nominal cross-sectional area, length and, where applicable, insulation and cable construction, and

b) follow the same route and have the same installation method(s).

6.2.2 Particular applications

6.2.2.1 Motors

6.2.2.1.1 The current-carrying capacity of the circuit conductors for a motor shall be at least equal to the full-load rated current of the motor. Possible increases in temperature owing to long or frequent starting shall be taken into consideration.

6.2.2.1.2 In the case of a circuit that supplies two or more motors, the current-carrying capacity of the conductors shall be at least equal to the sum of the full-load rated current of the motors, but a lower current-carrying capacity may be used if there is cyclic loading.

6.2.2.2 Discharge lighting

The nominal cross-sectional area of the neutral conductor in a three-phase circuit that supplies discharge lighting shall be at least equal to the nominal cross-sectional area of the associated phase conductor.

Note Without power-factor correction, a discharge lamp luminaire with magnetic ballast might have a current as much as 64% higher than a power-factor corrected luminaire and would require bigger conductors and protection.

6.2.3 Basis of tabulated current-carrying capacity

6.2.3.1 The current-carrying capacity of conductors and cables set out in this clause takes account of I.E.C standards, where applicable. For types of cable not covered in the relevant I.E.C publication (for example, armoured cables) the current-carrying capacity given in this clause is based on data provided by the Association of Electric Cable Manufacturers of South Africa.

6.2.3.2 The tabulated current-carrying capacity (given in tables 6.2(a) to 6.9(b)) relates to continuous loading and is also known as the "full thermal current rating" of the cable, corresponding to the conductor operating temperature indicated in the headings to the tables concerned. This current-carrying capacity is intended to provide for a satisfactory life of conductors and insulation subject to the thermal effects of carrying current for sustained periods in normal service. A cable can be seriously damaged, leading to early failure, or its service life can be significantly reduced, if it is operated for any prolonged period at a temperature higher than the indicated value.

6.2.3.3 In addition, there are other considerations that affect the choice of cross-sectional area of a conductor, such as the requirements for protection against electric shock, protection against thermal effects, overcurrent protection, voltage drop and limiting temperatures for terminals of equipment to which the conductors are connected.

6.2.3.4 The tabulated current-carrying capacity (given in tables 6.2(a) to 6.9(b)) relates to a single circuit in the installation methods (shown in table 6.1), in an ambient air temperature of 30 ^{circle}C . The current-carrying capacity (given in the said tables) for a.c. operation applies only to frequencies in the range 49 Hz to 61 Hz.

Table 6.1 summary: A classification system that assigns installation method numbers to various cable placement scenarios. Method 1 is used for cables in conduit within thermally insulating walls and certain building voids, as well as sheathed cables in building structure ducts with small diameters or perimeters. Method 2 applies to cables in conduit on walls or ceilings, those embedded in non-insulating masonry, and various trunking applications including flush floor and skirting trunking. Method 3 covers cables clipped direct to non-metallic surfaces and those embedded direct in non-insulating building materials. Method 4 is specified for bunched, unenclosed sheathed cables on perforated cable trays. Method 5 and 6 pertain to cables in free air on cleats, brackets, or ladders, depending on the cable type and spacing; for example, Method 5 is for certain single-core configurations and trefoil arrangements, while Method 6 is for multicore cables with separation exceeding two times the cable diameter. These methods also apply to cables supported on the walls of open or ventilated trenches. Method 7, 8, and 9 are reserved for cables in enclosed trenches of increasing minimum dimensions, ranging from 450 by 300 millimeters up to 600 by 760 millimeters. Finally, cables buried directly in the ground are not assigned a method number here but instead refer to specific ratings and correction factors in tables 6.8, 6.11, and 6.12.

6.2.3.5 In extreme cases, notably for large multicore cables, the reduction in current-carrying capacity of the cables (for example, balanced 400 Hz a.c. compared with the current-carrying capacity at 50 Hz), may be as much as 50%.

6.2.3.6 For small cables and flexible cords, such as may be used to supply individual tools, the difference between 50 Hz and the 400 Hz current-carrying capacities may be negligible.

6.2.4 Methods of cable installation

Table 6.1 lists the descriptions and the numbers of installation methods to be used for the determination of the current-carrying capacities of conductors in the selection of the appropriate cable size. The use of other methods is not precluded where a suitably qualified person has specified it.

For other conditions, appropriate correction factors shall be applied as described in 6.2.5.

6.2.5 Application of tables and correction factors for current-carrying capacity

6.2.5.1 To determine the current-carrying capacity of a cable for a particular method of installation, multiply the value of current-carrying capacity obtained from tables 6.2(a) to 6.9(b) by the correction factors for each of the following, where applicable:

a) ambient temperature (see table 6.10);

b) grouping and number of cables on racks or trays (see table 6.14);

c) grouping and number of cables in a trench (see table 6.15);

d) grouping and number of cables buried directly in the ground (see tables 6.11, 6.12, 6.13 and 6.16);

e) neutral imbalance (see table 6.17);

f) harmonics (see table 6.18); and

g) direct solar radiation (see table 6.19).

Table 6.10 summary: Correction factors for ambient temperature based on insulation type and operating temperature. As ambient temperature increases, the correction factor decreases. For General purpose PVC at 70 degrees Celsius, factors range from 1,22 at 10 degrees down to 0,50 at 60 degrees, with no values listed above 65 degrees. For Rubber at 85 degrees Celsius, factors range from 1,18 at 10 degrees down to 0,30 at 80 degrees. For Rubber at 150 degrees Celsius, the factor remains constant at 1,0 from 10 to 85 degrees, then decreases from 0,96 at 90 degrees down to 0,28 at 145 degrees.

: Table 6.11 summary: Correction factors for cables buried directly or in pipes in the ground based on soil temperature, assuming a maximum conductor temperature of 70 degrees Celsius. As the soil temperature increases, the correction factor decreases. For example, at 10 degrees Celsius, the factor is 1,15, which drops to 1,00 at 25 degrees Celsius, and continues down to 0,82 when the soil temperature reaches 40 degrees Celsius.

: Correction factors for grouping of cables buried in the ground. As the number of cables in a group increases or the center-line spacing decreases, the correction factors generally decrease, indicating a greater reduction in current-carrying capacity. For cables buried directly in the ground, factors range from 0.44 for 12 cables that are touching, up to 0.94 for 2 cables with 600 millimeter spacing. Cables installed in pipes generally maintain higher correction factors than those buried directly; for example, with 12 cables touching, the factor for pipes is 0.65 compared to 0.44 for direct burial.

: Correction factors for groups of single-core or multicore cables based on the installation method and the number of circuits or cables. As the number of circuits increases from 2 up to 20, the correction factors generally decrease, indicating a greater reduction in current-carrying capacity. The highest correction factors are found in spaced configurations, such as cables clipped to a non-metallic surface (method 3), where the factor remains constant at 0,90 for 3 or more circuits. In contrast, touching cables see a more significant drop; for example, method 3 touching cables drop from 0,85 for 2 circuits to 0,70 for 10 circuits. Similar trends appear across other methods, including those on perforated metal cable racks or trays (method 4) and ladder supports (method 6), where factors for touching cables typically range from roughly 0,86 down to 0,66 or 0,70 depending on the number of racks and circuits.

Table 6.15 summary: Correction factors for cables in enclosed trenches across installation methods 7, 8, and 9. As the conductor cross-sectional area increases from 4 square millimeters up to 630 square millimeters, the correction factors consistently decrease across all installation methods and cable configurations. Higher cable counts lead to lower correction factors; for instance, at a cross-sectional area of 4 square millimeters, the factor is 0.93 for two single-core cables in installation method 7, but drops to 0.69 for twenty-four single-core cables in installation method 9. This trend continues for larger conductors, where a 630 square millimeter cable has a factor of 0.77 for the simplest configuration in method 7, falling to 0.41 for the most complex configuration in method 9.

Table 6.16 summary: Correction factors for cable burial depth decrease as the depth increases, with cables buried directly in the ground experiencing a steeper decline in their factor than those installed in pipes. For a depth of 0.5 meters, both installation methods have a correction factor of 1.0. At the deepest listed point of 1.5 meters, the factor for cables buried directly in the ground drops to 0.9, while the factor for cables in pipes is higher at 0.94.

Table 6.17 summary: Correction factors for neutral imbalance decrease as the neutral current increases relative to the phase current. When the neutral current is 0 percent, the correction factor is 1,00, and it drops steadily to 0,90 when the neutral current reaches 75 percent of the phase current.

Table 6.18 summary: Correction factors for harmonic currents in multiphase circuits depend on the third harmonic content percentage and the basis for size selection. For circuits with 0 to 15 percent third harmonic content, a correction factor of 1.0 is applied when sizing based on phase current. For 15 to 33 percent content, a factor of 0.86 is used for both phase current and zero sequence current in the neutral. For 33 to 45 percent content, the factor is 1.0 when sizing based on zero sequence current in the neutral. When CFL or LED lighting is installed, conductor ratings must be based on double the sum of the rated input current or double the total lamp load in watts to account for harmonic currents.

Table 6.19 summary: Correction factors for direct solar radiation decrease as both the conductor's cross-sectional area and the intensity of solar radiation increase. For a coastal area with 1,000 watts per square meter, factors range from 0.70 for small conductors of 1.5 to 10 square millimeters down to 0.59 for larger conductors of 240 to 400 square millimeters. In highveld areas with higher radiation at 1,250 watts per square meter, the factors are lower across all sizes, starting at 0.62 for the smallest conductors and dropping to 0.44 for the largest.

6.2.5.2 Once the current-carrying capacity has been determined, after all correction factors had been considered, carry out the load power factor and voltage drop calculations to determine whether the voltage drop will be within the allowed 5%.

6.2.6 Effective current-carrying capacity

6.2.6.1 The current-carrying capacity of a cable corresponds to the maximum current that can be carried in specified conditions without the conductors exceeding the permissible limit of steady state temperature for the type of insulation concerned.

6.2.6.2 The value of a tabulated current represents the effective current-carrying capacity only where no correction factor is applicable. Otherwise the current-carrying capacity of a cable corresponds to the tabulated value multiplied by the appropriate correction factor or factors for ambient temperature, grouping, neutral imbalance, harmonics, thermal insulation and solar radiation, as applicable.

6.2.6.3 Irrespective of the type of overcurrent protective device associated with the conductors concerned, the ambient temperature correction factors to be used when calculating current-carrying capacity (as opposed to those used when selecting cable sizes) are given in table 6.10.

6.2.6.4 For the size and construction of a cable and for the conditions of use, other than those covered in this clause and the following tables, the current-carrying capacity shall be taken as that specified by the manufacturer or as given in S.A.N.S 10198 to 4.

6.2.6.5 Conditions of installation for cables buried in the ground are given in tables 6.8, 6.11, 6.12, 6.13 and 6.16. For cables not covered, see S.A.N.S 10198 to 4.

Table 6.8 summary: Current-carrying capacities for multicore PVC insulated armoured cables buried directly in the ground according to SANS 1507. The current rating increases consistently with the nominal conductor size for both copper and aluminium cables. In all configurations, two-core cables have the highest capacity, while three-core or four-core cables have the lowest. Additionally, cables buried directly in the ground are rated higher than those installed in pipes or ducts. For copper cables, ratings range from 20 amperes for a 1.5 square millimeter three-core cable in a duct up to 624 amperes for a 400 square millimeter two-core cable buried directly. Aluminium cables start at a conductor size of 25 square millimeters, with capacities ranging from 73 amperes for three-core cables in a duct up to 225 amperes for two-core cables buried directly. These ratings assume a burial depth of 0.5 meters, a soil thermal resistivity of 1.2 Kelvin meters per watt, and that each cable is thermally independent.

6.2.6.6 Where C.F.L (compact fluorescent lamp) lighting is installed, the rating of the conductors shall be based on double the sum of the lamp load, in watts (see also 6.2.11.2.3 and 6.14).

Ambient temperature: 30 °C Conductor operating temperature: 70 °C

Conductor operating temperature: 70 °C

Ambient temperature: 30 °C Conductor operating temperature: 70 °C

Conductor operating temperature: $ 70\,^{\circ}C $

Ambient temperature: $ 30\ °C $

Ambient temperature: 30 °C Conductor operating temperature: 70 °C

Ambient temperature: 30 °C

Conductor operating temperature: 70 °C

Ambient temperature: $ 30\ °C $

Conductor operating temperature: 70 °C

Conductor operating temperature: 70 °C

Soil temperature: 25 °C Maximum conductor temperature: 70 °C

Ambient temperature: 30 °C Conductor operating temperature: 85 °C or 150 °C

Table 6.2(a) summary: Current-carrying capacity in amperes for single-core copper PVC insulated unarmoured cables with conductor cross-sectional areas ranging from 1 square millimeter to 1,000 square millimeters. Current capacity increases with the conductor cross-sectional area and the effectiveness of the installation method for heat dissipation. For any given conductor size, the highest current capacities are achieved using Installation method 5 in free air, with the maximum value of 1,420 amperes for a 1,000 square millimeter conductor under the condition of two cables, single-phase a.c. or d.c. or three cables, three-phase a.c. Conversely, the lowest capacities occur in Installation method 1, where cables are enclosed in conduit in a thermally insulating wall; for example, a 1 square millimeter conductor is limited to 10.5 amperes for three or four cables, three-phase a.c. Other installation methods, including clipped direct (method 3) and perforated cable trays (method 4), provide intermediate current capacities.

: Voltage drop per ampere per metre for single-core PVC insulated, unarmoured copper conductors of various cross-sectional areas. The primary trend is that voltage drop decreases significantly as the conductor cross-sectional area increases. For example, with two cables in a dc configuration, the voltage drop falls from 44 millivolts per ampere per metre at 1 square millimetre to 0.042 millivolts per ampere per metre at 1,000 square millimetres. The data differentiates between single-phase and three-phase alternating current across various installation methods. Generally, higher conductor areas result in lower voltage drop regardless of the installation method, such as being enclosed in a conduit, clipped direct, or arranged in trefoil. For larger cables, such as those at 120 square millimetres and above, the table provides detailed resistance, reactance, and impedance values for each installation method, showing that voltage drop is influenced by both the physical layout of the cables and the chosen installation method.

Table 6.3(a) summary: Current-carrying capacity for unarmoured multicore PVC insulated copper conductors according to SANS 1507. Current capacity increases as conductor cross-sectional area increases, ranging from 1 square millimeter up to 400 square millimeters. Capacity is highest for Installation method 4 or 6 (perforated cable tray or free air) and lowest for Installation method 1 (enclosed in an insulating wall). For a 16 square millimeter conductor, capacity ranges from 52 to 57 amps under Installation method 1, increasing to 94 amps under Installation method 4 or 6. For a 120 square millimeter conductor, the capacity ranges from 172 to 192 amps under Installation method 1, reaching up to 328 amps under Installation method 4 or 6. Across all installation methods, larger cables for three-phase a.c. typically have lower current capacities than those for single-phase a.c. or d.c.

: Voltage drop for copper conductors in unarmoured multicore PVC insulated cables per ampere per metre. Voltage drop decreases consistently as the conductor cross-sectional area increases. For smaller conductors from 1 to 16 square millimetres, the voltage drop for two-core cables in both d.c. and single-phase a.c. is identical, ranging from 44 millivolts per ampere per metre for the 1 square millimetre cable down to 2,8 millivolts per ampere per metre for the 16 square millimetre cable. For these same sizes, three-core or four-core three-phase a.c. cables show slightly lower voltage drops, starting at 38 and ending at 2,4 millivolts per ampere per metre. For larger conductors from 25 to 400 square millimetres, all three configurations show a continuing decline. For example, the 400 square millimetre cable has the lowest voltage drops, with 0,105 millivolts per ampere per metre for two-core d.c., 0,155 for two-core single-phase a.c., and 0,160 for three-phase a.c.

Table 6.4(a) summary: Current-carrying capacities for copper conductors in multicore PVC insulated armoured cables according to SANS 1507. Current capacity increases as the conductor cross-sectional area grows, ranging from 1.5 square millimeters to 400 square millimeters. For any given cable size, Installation method 4 or 6, involving free air or perforated trays, allows for higher currents than Installation method 3, which is clipped direct. Additionally, single-phase a.c. or d.c. two-core cables consistently support more current than three-phase a.c. three-core or four-core cables of the same size. For example, at a cross-sectional area of 120 square millimeters, the capacity is 336 amperes for a two-core cable in free air, compared to 310 amperes for the same cable clipped direct, and 290 amperes for a three-phase cable in free air.

Table 6.4(b) summary: Voltage drop for copper conductors in multicore PVC insulated armoured cables according to SANS 1507. The voltage drop, measured in millivolts per ampere per metre, decreases significantly as the conductor cross-sectional area increases. For small cables, such as 1.5 square millimetres, the drop is 29 millivolts for two-core d.c. and single-phase a.c. cables, and 25 millivolts for three- or four-core three-phase a.c. cables. At the largest size shown, 400 square millimetres, these values drop to 0.105 millivolts for two-core d.c., 0.115 millivolts for single-phase a.c., and 0.160 millivolts for three-phase a.c. cables.

Table 6.5(a) summary: Current-carrying capacities for single-core PVC insulated aluminium cables, categorized by conductor cross-sectional area and five distinct installation methods. Capacity generally increases with the conductor size, which ranges from 50 to 1,200 square millimeters. The installation methods vary from enclosed in conduit in thermally insulating walls to free air configurations. For a 50 square millimeter conductor, capacity ranges from 84 amperes for three-phase cables in thermally insulating walls to 163 amperes for horizontal flat spaced cables in free air. As conductor size increases to 1,200 square millimeters, capacity reaches up to 1,293 amperes for horizontal flat spaced cables in free air, while installation methods like enclosed in conduit are not applicable for these larger sizes. The data reflects performance differences based on cable arrangement, such as flat, touching, or trefoil configurations.

Table 6.5(b) summary: Voltage drop per ampere per metre for unarmoured, single-core PVC insulated aluminium conductors of various cross-sectional areas, ranging from 50 to 1,200 square millimetres. Across all installation methods, the voltage drop consistently decreases as the conductor cross-sectional area increases. For example, in two-cable d.c. installations, the voltage drop falls from 1.55 millivolts per ampere per metre at 50 square millimetres to 0.060 millivolts per ampere per metre at 1,200 square millimetres. The table compares three main configurations: two-cable d.c., two-cable single-phase a.c., and three or four-cable three-phase a.c. Within these, it contrasts different installation methods, such as cables enclosed in conduit (methods 1 and 2), cables clipped direct or on trays (methods 3 and 4), and spaced installations (method 5). For three-phase a.c., it further differentiates between trefoil and flat formations, both touching and spaced.

Table 6.6(a) summary: Current-carrying capacity in amperes for unarmoured multicolore PVC insulated aluminium conductors according to SANS 1507. Current capacity increases as the conductor cross-sectional area increases from 16 to 300 square millimeters and improves as installation methods move from restricted to free air. For a 16 square millimeter conductor, the capacity ranges from 41 amperes for three-phase cables in an insulating wall to 61 amperes for single-phase cables in free air. At the largest listed size of 300 square millimeters, the capacity for three-phase cables ranges from 237 amperes in an insulating wall to 381 amperes in free air. Generally, single-phase cables support higher currents than three-phase cables of the same cross-sectional area within the same installation method.

Table 6.6(b) summary: Voltage drop specifications for unarmoured multicore PVC insulated cables with a conductor operating temperature of 70 degrees Celsius. As the conductor cross-sectional area increases from 16 to 300 square millimeters, the voltage drop in millivolts per ampere per meter generally decreases across all cable types. For example, at a cross-sectional area of 16 square millimeters, the two-core cable d.c. and single-phase a.c. values are 4.5, while the three- or four-core cable three-phase a.c. value is 3.9. At the largest size of 300 square millimeters, values are only provided for three-phase a.c. cables, showing a resistance of 0.21 and a total impedance of 0.25.

: Current-carrying capacity in amperes for multicore PVC insulated armoured cables with aluminium conductors. The capacity increases steadily as the conductor cross-sectional area grows from 16 up to 300 square millimeters. For example, at a cross-sectional area of 16 square millimeters, capacities range from 58 to 71 amperes depending on the installation method and cable core count. At the largest listed area of 300 square millimeters, the capacity reaches 360 amperes for a three-core or four-core cable under installation method 3, and 399 amperes for the same cable type under installation methods 4 or 6. Generally, three-core or four-core cables for three-phase a.c. have higher current-carrying capacities than two-core cables for single-phase a.c. or d.c. across the same cross-sectional areas and installation methods.

><?Table 6.7(b) summary: Voltage drop values per ampere per metre for aluminium conductors in multicore PVC insulated armoured cables per SANS 1507. The voltage drop generally decreases as the conductor cross-sectional area increases. For example, in three-phase a.c. cables, the value drops from 3,9 millivolts per ampere per metre at a 16 square millimetre cross-section down to 0,21 at 300 square millimetres. The table provides data for two-core cable d.c., two-core cable single-phase a.c., and three-core or four-core cable three-phase a.c., with the latter providing the most comprehensive range of conductor sizes from 16 to 300 square millimetres.

Table 6.9(a) summary: Current-carrying capacities for copper conductors in 85 degree Celsius or 150 degree Celsius rubber-insulated and silicon-rubber-insulated flexible cables. Capacity increases as conductor cross-sectional area increases. For the smallest area of 4 square millimeters, capacities range from 36 amps for three-phase alternating current to 41 amps for direct current or single-phase alternating current. At the upper end of the scale, for a cross-sectional area of 630 square millimeters, the capacity for two touching single-core cables is 1 190 amps. The ratings are for cables in free air or resting on a surface, but must be reduced if the cable is covered or wound on a drum. For example, cables on a radial type drum are reduced by a factor of 0.85 if ventilated and 0.75 if non-ventilated, while ventilated cylindrical type drums see further reductions as layers increase, falling from 0.85 for one layer down to 0.35 for four layers.

Table 6.9(b) summary: Voltage drop for copper conductors in rubber-insulated and silicon-rubber-insulated flexible cables, measured in millivolts per ampere per metre. As the conductor cross-sectional area increases from 4 square millimetres to 630 square millimetres, the voltage drop consistently decreases across all cable configurations. For an area of 4 square millimetres, the voltage drop is 13 millivolts per ampere per metre for d.c. and single-phase a.c. two-core cables, and 11 for three-phase a.c. cables. At the largest area of 630 square millimetres, the d.c. voltage drop falls to 0.073, while the two single-core cables touching configuration shows a drop of 0.19 for the z component. The values provided are based on an operating temperature of 85 degrees Celsius; for 150 degrees Celsius cables operating at that temperature, resistive values should be increased by a factor of 1.2.

6.2.7 Voltage drop

6.2.7.1 Difference in voltage (voltage drop)

6.2.7.1.1 When all conductors of an a.c. installation are carrying their design load, the difference in voltage (the voltage drop) between the point of supply and any point of outlet or terminals of fixed appliances shall not exceed 5% of the standard or declared voltage. (See 5.3.2 and 5.4.2.)

In the case of a 230/400 V system, the voltage drop for single-phase circuits shall not exceed 11.5 V (5% of 230 5) and the voltage drop for three-phase circuits shall not exceed 20 V (5% of 400 5).

In the case of single-phase circuits derived from three-phase supplies with balanced loading, the phase-to-neutral voltage drop is calculated from three-phase values divided by square root of 3 .

Note 1 If the phase-to-neutral voltage is not declared, the value can be calculated by dividing the phase-to-phase voltage by 1.73.

Note 2 In the case where reticulation is part of the electrical installation after the point of supply, the 5% voltage drop should be calculated to include the reticulation part of the installation (for example, in the case of a housing scheme where submetering with a further point of control is installed for individual consumers) (see 5.3.2.1).

6.2.7.1.2 When all conductors of a d.c. installation are carrying their maximum estimated load, the difference in voltage (the voltage drop) between any point of supply and any point of consumption shall not exceed 5% of the circuit nominal voltage or shall comply with the requirements of the manufacturer of the equipment connected to the circuit.

6.2.7.2 Tables of voltage drop

Note The values in the tables for a.c. operation apply only to frequencies in the range 49 Hz to 61 Hz. The values of voltage drop for cables that operate at higher frequencies may be substantially greater.

6.2.7.2.1 In tables 6.2(b) to 6.9(b), values of voltage drop are given for a current of one ampere for a distance of 1 m along the route taken by the cables and represent the result of voltage drop in all the circuit conductors. The values of the voltage drop assume that the conductors are at their maximum permitted normal operating temperatures.

6.2.7.2.2 For a given run of cable, to calculate the voltage drop (in millivolts), the tabulated value of voltage drop per ampere per metre for the cable concerned has to be multiplied by the length of the run in metres and by the current the cable is intended to carry, that is the design current of the circuit, in amperes. In the case of three-phase circuits, the tabulated millivolts/A/m values relate to the line voltage and balanced conditions have been assumed.

6.2.7.2.3 In the case of cables that have conductors of cross-sectional area exceeding 16 millimeters squared, the impedance values are given as (millivolts/A/m)₂, together with the resistive component (millivolts/A/m)₁ and the reactive component (millivolts/A/m)ₓ. In the case of cables that have conductors of cross-sectional area 16 millimeters squared or less, their inductances can be ignored and (millivolts/A/m)₁ values only are tabulated.

6.2.7.2.4 The direct use of the tabulated (millivolts/A/m) _{r} values or (millivolts/A/m) _{z} values, as appropriate, can lead to pessimistically high calculated values of voltage drop or, in other words, to unnecessarily low values of permitted circuit lengths.

6.2.7.2.5 For example, where the design current of a circuit is significantly less than the effective current-carrying capacity of the cable chosen, the actual voltage drop would be less than the calculated value because the conductor temperature (and hence its resistance) will be less than that on which the tabulated values were based.

6.2.7.2.6 As regards power factor in a.c. circuits, the use of the tabulated millivolts/A/m values (for the larger cable sizes, the tabulated (millivolts/A/m) _{2} values), to calculate the voltage drop is correct only when the phase angle of the cable equals that of the load. When the phase angle of the cable does not equal that of the load, the direct use of the tabulated millivolts/A/m values or (millivolts/A/m) _{2} values leads to a calculated value of voltage drop higher than the actual value. In some cases it might be advantageous to take account of the power factor of the load when voltage drop is being calculated.

Note The voltage drop can also be calculated by using the alternate method given in D.2 Values in tables D.1 to D.3 are average values for the purpose of easy calculation and can differ from cable manufacturer's data.

6.2.7.3 Power factor corrections

6.2.7.3.1 In the case of cables that have conductors of cross-sectional area 16 square millimeters or less, the approximate design value of millivolts per ampere per meter is obtained by multiplying the tabulated value by the power factor of the load, cosine phi.

6.2.7.3.2 In the case of cables that have conductors of cross-sectional area exceeding 16 millimeters, the approximate design value of millivolts/A/m is calculated by the following equation:

millivolts/A/m = cos ϕ (tabulated (millivolts/A/m)ₜ) + sin ϑ (tabulated (millivolts/A/m)ₓ)

6.2.7.3.3 In the case of single-core cables in flat formation, the tabulated values apply to the outer cables and could underestimate the voltage drop between an outer cable and the centre cable for cross-sectional areas above 240 millimeters and power factors exceeding 0.8.

6.2.8 Correction factors for ambient temperature

6.2.8.1 The ambient temperature of a cable shall be taken as the temperature of the air that surrounds the cable under normal operating conditions. Allowances for heating caused by other heat sources within the building shall be included, but heating of the cable itself shall be ignored.

6.2.8.2 If the ambient temperature varies along the cable route, the correction factor selected shall be the one appropriate to the part of the route where the most adverse conditions are created. From table 6.10, select the correction factor appropriate to the ambient temperature and to the type of cable.

6.2.8.3 Where wiring systems are surrounded by thermal insulation, for example, above ceilings and wall cavities, the correction factor that corresponds to an ambient temperature of 60 degrees Celsius shall be used (see table 6.10).

6.2.8.4 Cables spaced up to 600 millimeters apart still have a thermal influence on one another when buried direct or in pipes in the ground. The soil temperature, thermal resistivity of the soil and the grouping of cables also affect the sustained current-carrying capacity of a cable (see tables 6.11, 6.12 and 6.13).

Table 6.12 summary: Correction factors for thermal resistivity of soil, measured in K dot m per W, decrease as the soil's thermal resistivity increases. For cables buried directly in the ground, the factor drops from 1.17 at a resistivity of 0.7 to 0.61 at a resistivity of 4.0. For cables installed in pipes buried in the ground, the factor is generally higher but follows a similar downward trend, moving from 1.07 at a resistivity of 0.7 down to 0.77 at 4.0. Both installation methods reach a neutral correction factor of 1.00 when the thermal resistivity is 1.2. These values are averaged over various conductor sizes.

Note 1 The current-carrying capacity of a cable that is exposed to the direct rays of the sun could be considerably less than that determined in accordance with the above. (See also table 6.19.)

Note 2 The very high ambient temperatures that can occur in a roof space should be taken into consideration when the current-carrying capacity of a cable installed in such a situation is being determined.

6.2.8.5 The sustained current-carrying capacity I(A) of a cable buried directly in the ground can be calculated by the following equation:

Math summary: This expression calculates the sustained current-carrying capacity of a cable buried directly in the ground. The result is determined by multiplying a base current value by four separate scaling factors.

where

I s is the standard rating, in amperes (A);

F 1 is the rating factor for depth of burial, given in table 6.16;

F 2 is the rating factor for soil temperature at depth of burial, given in table 6.11;

F 3 is the rating factor for thermal resistivity of soil, given in table 6.12;

F 4 is the rating factor for grouping of directly buried cables that are thermally interdependent, given in table 6.13.

6.2.9 Correction factors for grouping and number of cables

6.2.9.1 Groups that contain cables of the same size and load

The correction factors for grouping, as given in tables 6.14 or 6.15, are applicable to adjacent cables that are a) in uniform groups (that is groups in which the cables are all single-core or all multicore), and

b) equally loaded (that is all the cables are loaded to their respective current-carrying capacities).

Note When the spacing between cables exceeds twice the overall diameter of the cables, no correction factor for grouping need be applied except for cables buried directly in the ground.

6.2.9.2 Correction factors for number of cables on racks or trays

Note Only the number of conductors that carry load current shall be considered in a circuit. Where it can be assumed that conductors in multiphase circuits carry balanced currents, the associated neutral conductor need not be taken into consideration. Therefore the tabulated current-carrying capacities for three conductors apply to conductors in a balanced three-phase and neutral circuit; under these conditions, a four-core cable is taken as having the same current-carrying capacity as a three-core cable, each phase conductor having the same nominal cross-sectional area.

6.2.9.2.1 Where two or more conductors are connected in parallel in the same phase or pole of the system, measures shall be taken to ensure that the load current is shared equally between them.

6.2.9.2.2 From table 6.1, select the installation method appropriate to the installation arrangement.

The correction factors tabulated below relate to the disposition of cables illustrated in table 6.1 (cables in trenches) and are applicable to the current-carrying capacities of cables installed in accordance with installation methods 5 or 6 of table 6.1, as given in the relevant tables.

(To be applied to the corresponding current-carrying capacity for a single circuit in tables 6.1 to 6.6.) $ ^{a} $

6.2.9.3 Groups that contain cables of different sizes

Tabulated group correction factors are applicable to groups that consist of similar, equally loaded cables. The calculation of correction factors for groups that contain different sizes of equally loaded insulated conductors or cables is dependent on the total number of cables and the different sizes in the group. Such factors cannot be tabulated but shall be calculated separately for each group.

The method of calculation of such factors is beyond the scope of this standard. Examples of where such calculations might be advisable are given below.

The group correction factor F for a group that contains different sizes of insulated conductors or cables in conduits, cable trunking or cable ducting can be calculated as follows:

Math summary: This expression calculates the group correction factor for insulated conductors or cables in conduits, trunking, or ducting. The factor is determined by taking the reciprocal of the square root of the number of conductors.

where

- F is the group correction factor;

- n is the number of multicore cables or circuits in the group.

Note 1 A group that contains sizes of conductor that cover a range of more than three adjacent standard sizes can be considered a group that contains cables of different sizes. A group of similar cables where the range of conductor sizes in the group covers not more than three adjacent standard sizes, is taken to be a group that consists of cables of the same sizes and loads where the current-carrying capacity of all the cables is based on the same maximum permissible conductor temperature.

Note 2 Table 6.15 gives the correction factors to be applied to the tabulated current-carrying capacities of cables or circuits where the cables (circuits) are installed in enclosed trenches.

6.2.9.4 Groups of cables buried directly or installed in pipes buried in the ground

The number of cables, the grouping of the cables and the depth of the cables in the ground have a direct influence on the operating temperature of a cable (see tables 6.11, 6.12, 6.13 and 6.16).

6.2.10 Correction factors for neutral currents

6.2.10.1 Where the neutral conductor carries current without a corresponding reduction in the load of the phase conductor, the current that flows in the neutral conductor shall be taken into account in ascertaining the rating of the circuit.

Select the appropriate correction factor from table 6.17.

Note Neutral current can be caused, for example, by a) unbalanced circuit conditions, and

b) harmonic current in three-phase circuits.

6.2.10.2 Irrespective of 6.2.10.1, the current-carrying capacity of a neutral conductor shall a) in a single-phase circuit, be at least equal to that of the phase conductor.

b) in a multiphase circuit (when single-pole protective devices are used), be at least equal to that of the phase conductor,

c) in a multiphase circuit that uses a multipole protective device, be such that the neutral conductor can carry the maximum predictable out-of-balance current under normal operating conditions, and

d) in a three-phase circuit that supplies discharge lighting, the nominal cross-sectional area of the neutral shall be at least equal to the nominal cross-sectional area of the associated phase conductor.

6.2.11 Correction factors for harmonic currents

6.2.11.1 Effects of harmonic currents on balanced three-phase systems

6.2.11.1.1 In the situation where current flows in the neutral of a balanced three-phase system, such neutral currents are due to the line current having a harmonic content that does not cancel in the neutral. The most significant harmonic which does not cancel in the neutral is usually the third harmonic. The magnitude of the neutral current due to the third harmonic may exceed the magnitude of power frequency phase current. The neutral current will then have a significant effect on the current-carrying capacity of cables in the circuit.

6.2.11.1.2 The correction factors apply to balanced three-phase circuits; it is recognized that the situation is more onerous if only two of the three phases are loaded. In this situation the neutral conductor will carry the harmonic currents in addition to the unbalanced current; such a situation can lead to overloading of the neutral conductor.

6.2.11.1.3 Equipment likely to cause significant harmonic currents is, for example, fluorescent lighting banks and d.c. power supplies such as those found in computers.

6.2.11.1.4 The tabulated correction factors, when applied to the current-carrying capacity of the cable with three loaded conductors, will give the current-carrying capacity of a cable with four loaded conductors where the current in the fourth conductor is due to harmonics. The correction factors also take the heating effect of the harmonic current in the phase conductors into account.

6.2.11.1.5 Further information on harmonic disturbances can be found in S.A.N.S 61000-4-7.

6.2.11.2 Harmonic currents in four-core and five-core cables with four cores that carry current

6.2.11.2.1 Where the neutral conductor carries current without a corresponding reduction in the load of the phase conductor, the current that flows in the neutral conductor shall be taken into account in ascertaining the current-carrying capacity of the circuit.

6.2.11.2.2 The correction factors given in table 6.18 only apply to cables where the neutral conductor is in a multicore cable and is of the same material and cross-sectional area as the phase conductor. The correction factors calculated were based on third harmonic currents. If more than 10 % of higher harmonics (9th, 12th, etcetera), are experienced, the lower correction factors are applicable. Where there is an unbalance between phases of more than 50 %, the lower correction factors may be applicable.

6.2.11.2.3 Where the neutral current is expected to be higher than the phase current, the cable size shall be selected based on the neutral current (see 6.2.6.6).

6.2.11.2.4 Where the cable size selection is based on a neutral current, which is not significantly higher than the phase current, it is necessary to reduce the tabulated current-carrying capacity for the three loaded conductors.

6.2.11.2.5 If the neutral current is more than 135 % of the phase current and the cable size is selected based on the neutral current, the three phase conductors will not be fully loaded. The reduction in heat generated by the phase conductors offsets the heat generated by the neutral conductor to the extent that it is not necessary to apply any correction factor to the current-carrying capacity for three loaded conductors.

6.2.12 Correction factors for direct solar radiation

Select the appropriate correction factor from table 6.19.

6.2.13 Single-phase concentric cables for aerial service connections

6.2.13.1 Concentric and split concentric cables are single-phase X.L.P.E insulated copper cables available in sizes 4 millimeters ^2 , 10 millimeters ^2 and 16 millimeters ^2 and are designed for aerial application, but may also be used underground. These cables are primarily used for the provision of an electricity supply from a distribution main or aerial bundled conductor (A.B.C) system to individual houses. For current ratings, see table 6.20.

: Table 6.20 summary: The current ratings for concentric cables at 30 degrees Celsius increase as conductor size increases, with significantly higher ratings for cables in the ground than those in air under direct sunlight. For a conductor size of 4 square millimeters, the rating is 30 amps in air and 60 amps in ground. As the size increases to 16 square millimeters, the ratings rise to 70 amps in air and 130 amps in ground.

6.2.13.2 Split concentric cables are provided with an integral earthing conductor and can be used in single-phase circuits in an electrical installation.

6.2.13.3 Concentric cables only contain a phase and concentric conductor to be used in combined neutral earth systems which does not make it suitable for circuits in an electrical installation except where a separate earthing conductor is installed.

6.2.14 Aerial Bundled Conductors (A.B.C)

A.B.C cables consist of one to three X.L.P.E insulated aluminium conductors wound around a central supporting core, which is also insulated.

These cables are intended for reticulation systems from which individual houses can be fed by concentric or split concentric service cables.

For current ratings see table 6.21 and for installation see S.A.N.S 10198 to 14.

: Specifications for Aerial bundled conductors according to SANS 1418-1, applicable for still air at 35 degrees Celsius. As the conductor cross-section increases from 35 square millimeters up to 120 square millimeters, the current rating rises from 144 to 322 amps, the short-circuit rating increases from 3.2 to 11.0 kA, and the voltage drop at full load decreases from 1.93 down to 0.58 mV/A/m. For example, the 35 by 3 plus 54.6 conductor has a 50 Hz resistance of 1.113 ohms per kilometer, while the 120 by 3 plus 54.6 conductor reduces this to 0.325 ohms per kilometer. The insulated neutral nominal diameter remains constant at 12.65 mm for most models, increasing to 14.2 mm for the 120 by 3 plus 70 variant. All listed conductors are rated for a maximum continuous temperature of 90 degrees Celsius and a maximum 1-second temperature of 250 degrees Celsius.

A.B.C cables are intended to be suspended between structures and shall not be buried directly in the ground.

6.3 Installation of conductors and cables

6.3.1 Materials

All conductors of nominal cross-sectional area less than 16 millimeters ^2 shall be of annealed copper. In the following cases alternative material may also be used:

a) earth continuity conductors (see 6.12.1.9);

b) bonding conductors (see 6.13.1); and

c) aerial conductors (see 6.3.4).

6.3.2 Construction

6.3.2.1 Conductors of nominal cross-sectional area exceeding 2.5 millimeters ^2 shall be stranded, except in the following cases, where solid conductors may be used:

a) conductors of mineral-insulated metal-sheathed cables;

b) internal connections of distribution boards, switchgear and industrial controlgear;

c) busbars;

d) aerial conductors:

e) aluminium conductors of nominal cross-sectional area 16 square millimeters or more; and

f) copper conductors of nominal cross-sectional area 16 millimeters ^2 or less that are used in multicore cables.

6.3.2.2 Conductors shall be so insulated as to withstand the highest temperature and voltage to which they are likely to be exposed.

6.3.3 Identification

6.3.3.1 A conductor shall be identifiable at its terminations unless its purpose is obvious.

6.3.3.2 The means of identification for an a.c. circuit may be by colours or by numbers, as follows:

a) where colours are used

1) a neutral conductor shall be identified by black only.

2) an earth continuity conductor shall be identified by the bi-colour green/yellow only, or by being bare. Green/yellow insulated conductors shall not be used as live conductors under any circumstances.

3) a phase conductor shall be identified by a colour other than green/yellow, green or black, and

Note Welding cable manufactured to S.A.N.S 1576 should not be used in circuits above 100 V.

4) the colours may be applied at the ends of the conductor (of a multicore cable) by means of durable colour marking (for example insulating sleeves or by electrical insulating tape wound more than once around the conductor), and

b) where numbers are used, "0" shall indicate the neutral conductor.

Note Where the purpose or the function of a conductor is apparent, marking is not required.

6.3.3.3 The means of identification for a d.c. circuit may be by colours or by symbols, as follows:

a) All equipotential bonding, earth continuity and protective earthing conductors shall be identified by the bi-colour green/yellow only, or by being bare.

b) Where colours are used

1) the polarity of the positive conductor shall be identified by red only.

2) the polarity of the negative conductor shall be identified by black or blue, and

3) the colours may be applied at the ends of a conductor by means of durable colour marking (for example insulating sleeves or by electrical insulating tape wound more than once around the conductor).

c) Where symbols are used

1) the polarity of the positive conductor shall be identified by the + symbol.

2) the polarity of the negative conductor shall be identified by the - symbol, and

3) the symbols shall be applied at the ends of the conductor. The symbols may be applied by means of printed adhesive tape or cable markers.

d) In an earthed d.c. installation, either the positive or the negative conductor may be earthed. The earthing system used in the installation shall be indicated by means of a notice placed at the d.c. supply.

e) Where an installation contains both a.c. and d.c. circuits and colour is used to identify the polarity of the d.c. conductors, polarity symbols described in (c) above shall be added at both ends of the d.c. conductors to distinguish them from the a.c. conductors.

6.3.4 Aerial conductors

6.3.4.1 An aerial conductor shall be of a) hard-drawn copper.

b) stranded aluminium, or

c) composite construction, such as steel-cored aluminium.

6.3.4.2 A surge arrester should be installed at each end of each aerial conductor circuit in an installation (see 6.7.6).

The arrangement, support and, where required, insulation of an aerial conductor shall comply with the relevant statutory requirements.

6.3.5 Prefabricated wiring

6.3.5.1 A prefabricated wiring system that is not wired on site shall allow for variation in building dimensions in such a way that the system, including the cables, is not subjected to any strain.

6.3.5.2 A prefabricated wiring system, especially any exposed cable ends, shall be protected against damage both during and after installation.

6.3.6 P.V.C insulated multicore cables with a bare earthing conductor and round cable with metal stiffening

6.3.6.1 The cables may be installed

a) on the surface,

b) under plaster,

c) under a raised floor,

d) in hollows (such as in walls and partitions) (no additional protection being needed),

e) in roof spaces.

f) direct in the ground (see 6.4.4.2, unarmoured buried cables).

g) outdoors or exposed to water (but unless the manufacturer proves that the cables can withstand ultraviolet radiation, the cable shall be out of sight of the sky), and

h) under screed if protected by an earth leakage protection device with a rated earth leakage tripping current (rated residual current) l Delta n not exceeding 30 milliamperes.

6.3.6.2 These cables shall not be buried direct in concrete.

6.3.7 Joints and terminations

6.3.7.1 Joints and terminations of cables, cores and conductors shall be made in accordance with manufacturers' instructions or the appropriate part of S.A.N.S 10198. Flexible cables shall only be joined using termination boxes, cable couplers or manufacturers' jointing kits. All joints shall be accessible, protected against strain, and protected in accordance with 5.2.1, except for joints made and sealed permanently and intended to be maintenance free.

6.3.7.2 Joints and terminations shall not

a) adversely affect the current-carrying capacity, the insulation resistance or the earth continuity of the cable, core or conductor in which they are made,

b) be made in any connector, bend, elbow or tee-piece of a conduit.

c) allow the strands of a stranded conductor to spread, or

d) require strands of a stranded conductor to be cut away to allow connection of the conductors (for example, to terminals).

6.3.7.3 Any armouring or sheathing shall be terminated in or on equipment. Armour wires shall be terminated by a clamp or gland in such a way that a) pressure is not applied to insulating material, and

b) there is an earth tag washer (or similar) for connecting to the earth continuity conductor.

6.4 Positioning and fixing of cables

6.4.1 Positioning

A cable shall not be run a) in the same trench or wireway as a supplier's cable, except with the supplier's permission.

b) in the same wireway as the cables or wires of telecommunication, radio and signalling circuits that are not covered by this part of S.A.N.S 10142.

c) where it is likely to be damaged by liquids such as oil, acid, acetone and alkali or by gases such as sulfur dioxide.

d) within 150 millimeters of hot services such as hot pipes and flues if the heat is likely to damage the cable, unless the cable is cooled or shielded from heat, or

e) in a position where it is likely to be damaged, unless it is mechanically protected.

6.4.2 Separation

Where cables and wiring have to be kept separate, as in 6.4.1(b), barriers shall be used at cross-overs, junctions and terminations. In service tunnels and large wireways, barriers need not be used if the circuits can be kept separate, even when the wiring is being worked on.

6.4.3 Fixing

6.4.3.1 To avoid damage to the sheath of a cable, only appropriate cleats, saddles and clamps shall be used to fix a cable.

6.4.3.2 Cables shall be fixed in such a way as to prevent strain on terminals or connectors.

6.4.3.3 A cable shall not be bent more than is recommended by the cable manufacturer.

Note See annex E for information about bends in cables.

6.4.3.4 If a cable is not run on racks or in pipes or ducts, it shall be firmly fixed to prevent sagging or creeping.

Note 1 P.V.C insulated multicore cables with a bare earthing conductor may be fixed using adhesives recommended by the cable manufacturer.

Note 2 A cable installed in the space above a ceiling and that runs on the ceiling need not be fixed except at the ends to prevent strain on the conductors or terminations.

Note 3 A cable can be damaged if it sags under its own weight.

6.4.3.5 Each a. c. circuit shall be so arranged that

a) all live cores are in the same wireway.

b) when live single-core conductors go through electrically conductive material, measures shall be taken to minimize eddy current heating, and

c) when live single-core conductors go through magnetic material, measures shall be taken to avoid hysteresis losses.