Unit Standard 91761 Electrical Phase 1 hlayiso.com

MR TSHABALALA T.V. ELECTRICAL FACILITATOR Downloaded from hlayiso.com

PHASE 01 OF QCTO,UNIT STANDARD 91761 • MODULE:WIRE,FAULT FIND AND REPAIR FINAL DISTRIBUTION OF INDUSTRIAL,OFFICE AND DOMESTIC INSTALLATION. • TOPIC: INTRODUCTION, WIRING CONDUIT,DETERMINE THE CONDUCTOR’S SIZES AND ACCEPTABLE CIRCUIT CONDUCTOR SIZES. • PRESENTATION: WILL ASSIST YOU TO SELECT, DETERMINE AND USE OF ACCEPTABLE CONDUCTORS. • LEARNING OUTCOME: WIRE,FAULT FIND AND REPAIR FINAL DISTRIBUTION OF INDUSTRIAL, OFFICE AND DOMESTIC USE. Downloaded from hlayiso.com

INTRODUCTION • Conduit is normally installed prior to the walls being plastered. All openings such as wall boxes for light and plug sockets are protected by paper wadding to stop the ingress of plaster. • We have two types of installing wire ways, which internally and externally. • In most of the cases you have to use the Galvanised Boxes to prevent them from rust for internal use. • For external use we use what we call Extension Box with either surfix cable or conduit. Downloaded from hlayiso.com

CHASSED WALL Downloaded from hlayiso.com

CONDUIT INSIDE CHASSED WALL Downloaded from hlayiso.com

CONDUIT PLASTERED Downloaded from hlayiso.com

GALVANISED WALL BOX FOR INTERNAL USE Downloaded from hlayiso.com

EXTENSION BOX FOR EXTERNAL USE Downloaded from hlayiso.com

WIRING CONDUIT • Before commencing with the drawing conductors, it will be necessary to do the following: • Remove all paper wadding. • Check that wall boxes are accessible. • Check that wall boxes are square. • Check that draw boxes are open and free of plaster. • Check that no conduit protrudes from plaster. • Check that metal conduit ends are bushed and free of sharp edges and are tagged. • Check that PVC conduits are free of sharp edges and burrs. Downloaded from hlayiso.com

CONDUIT INSTALLED Downloaded from hlayiso.com

FLEXIBLE CONDUIT WITH JUNCTION BOX Downloaded from hlayiso.com

METAL CONDUIT PAINTED IN GREEN WITH JUCTION BOX Downloaded from hlayiso.com

DETERMINE THE CONDUCTOR SIZE • The following extracts from SABS 0142 Clause 6.27 apply: • CURRENT CARRYING CAPACITY OF CONDUCTORS • 6.27.1 GENERAL APPLICATION. NOTE: The required size of conductors is determined by considering the required current carrying capacity, the permitted voltage, the requirement for over current protection and short-time current rating. 6.27.1.1 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. Downloaded from hlayiso.com

6.27.1.2 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. • (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 once point only, a circuit may be split into two or more branches, each having conductors of reduced current- carrying capacity. Downloaded from hlayiso.com

6.27.1.3 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, •(B) follow the same route and have the same installation. Downloaded from hlayiso.com

6.27.1.4 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 protection devices are used), be at least equal that of the phase conductor, and • (C) in a multiphase circuit that uses a multipole protection device, be such that the neutral conductor can carry the maximum predictable out-of-balance current under normal operating condition. Downloaded from hlayiso.com

6.27.1.5 Flexible cords shall not be used as part of the electrical installation, except where • Amdt 3, Jan. 1996 • Require by the relevant product solely for termination or connection of moving parts. • Specified in the product standard. • Used as single cores in conduit, or • Used in an authorised wiring system. Amdt 5, Mar. 1997 • In learning guide/module of DS-01 & COCA – 01 you will learn about an electrical schematic layout plan prepared for the placing and sizing of the conduits. Downloaded from hlayiso.com

This electrical layout needs to be referred to when pulling in the conductors to make sure that the right size conductors is drawn in to the right circuit conduit. • NOTE: PVC INSULATED WIRE IS SUPPLIED IN UNSPOOLED COILS AND CARE MUST BE TAKEN DURING THE UNSPOOLING PROCESS AS FOLLOWS: • LEAVE THE WRAPPER ON THE AND MAKE A SMALL HOLE IN THE CENTRE OF THE COIL’S WRAPPER. • CAREFULLY PULL THE INNER END OF THE COIL OUT THROUGH THE HOLE (THIS WILL HELP PREVENT THE WIRE FROM BECOMING TANGLED DURING THE UNWINDING AND DRAWING IN PROCESS. Downloaded from hlayiso.com

ACCEPTABLE CIRCUIT CONDUCTOR SIZES The conductors that have been discussed in these notes are those that are used for wiring domestic houses, shops, and block of flats. • The following sizes are generally accepted for the wiring of the given circuits. BELL CIRCUITS – 1,0mm² LIGHT CIRCUITS – 1,5mm² PLUG (SOCKET OUTLET) CIRCUITS – 2,5mm² GEYSER CIRCUITS – 4,0mm² ELECTRIC STOVE CIRCUITS – 6,0mm² DISTRIBUTION BOARDS WIRING – 10mm² SUPPLY FROM METER TO D/B – 16mm² Downloaded from hlayiso.com

CONDUCTOR SIZES FOR LOW VOLTAGE Downloaded from hlayiso.com

CONDUCTOR SIZES FOR MEDIUM VOLTAGE Downloaded from hlayiso.com

QUICK CLASSWORK • QUESTION 1 : What procedures and checks must be performed before conductors are drawn through their respective conduits? • QUESTION 2: State the procedure which must be followed when unspooling coil of PVC insulated wire. • QUESTION 3: State the requirements of the current-carrying capacity of a neutral conductor. • QUESTION 4: State the size of conductors used for the wiring of the following circuits: Bell circuits, Lights circuits, geyser, electrical stove, socket outlet, distribution board wiring and main supply to D/B. Downloaded from hlayiso.com

ANSWERS • 1. Remove all paper wadding. • Check that wall boxes are accessible. • Check that wall boxes are square. • Check that draw boxes are open and free of plaster. • Check that no conduit protrudes from plaster. • Check that metal conduit ends are bushed and free of sharp edges and are tagged. • Check that PVC conduits are free of sharp edges and burrs. Downloaded from hlayiso.com

QUESTION 2 • LEAVE THE WRAPPER ON THE AND MAKE A SMALL HOLE IN THE CENTRE OF THE COIL’S WRAPPER. • CAREFULLY PULL THE INNER END OF THE COIL OUT THROUGH THE HOLE (THIS WILL HELP PREVENT THE WIRE FROM BECOMING TANGLED DURING THE UNWINDING AND DRAWING IN PROCESS. Downloaded from hlayiso.com

QUESTION 3 • (A) in a single-phase circuit, be at least equal to that of the phase conductor. • (B) In a multiphase circuit (when single-pole protection devices are used), be at least equal that of the phase conductor, and • (C) in a multiphase circuit that uses a multipole protection device, be such that the neutral conductor can carry the maximum predictable out-of-balance current under normal operating condition. Downloaded from hlayiso.com

QUESTION 4 BELL CIRCUITS – 1,0mm² LIGHT CIRCUITS – 1,5mm² PLUG (SOCKET OUTLET) CIRCUITS – 2,5mm² GEYSER CIRCUITS – 4,0mm² ELECTRIC STOVE CIRCUITS – 6,0mm² DISTRIBUTION BOARDS WIRING – 10mm² SUPPLY FROM METER TO D/B – 16mm² Downloaded from hlayiso.com

THE PRESENTATION WAS ALL ABOUT INTRO , WIRING CONDUIT, DETERMINING OF CONDUCTOR SIZES AND ACCEPTABLE CIRCUIT CONDUCTOR SIZES. • THE NEXT PRESENTATION WILL BE ON PREFABRICATED WIREWAYS, PREPAERATION FOR DRAWING IN THE CONDUCTORS, DRAW IN THE CONDUCTORS, WIRE SOCKET OUTLETS CIRCUITS, WIRE LIGHTS CIRCUITS, CONNECT STOVE CIRCUIT WITH ISOLATOR, CONNECT GEYSER CIRCUIT AND CONNECTION OF A DOORBELL. THANK YOU!!! Downloaded from hlayiso.com