QUICK OVERVIEW Practical Electricity Made Easy

This guide provides assistance to electrical trainers and trainees in need of quick access to

information on the electrical subject. Simplified user-friendly advice and explanations are

presented with colour diagrams and photographs. Sections and text are laid out in a logical order

and sequence that facilitates learning and to ensure an electrically safe installation.

Electrical systems and equipment must be installed and maintained in accordance with the

manufacturer's instructions and have to comply with the requirements of the South African

National Bureau of Standards.

Treat electricity with respect, as it can be harmful or fatal when used incorrectly. Always think

safety first and test before you touch.

ELECTRICIAN STATUS

There are pre-requisites to comply with,

prior to qualify as an Electrician.

One of these requirements is that a

person has to be assessed

(Trade Tested) at an Accredited

Trade Test Centre and be declared

competent as an Electrician.

“Practical Electricity Made Easy”

can be used as a guide during training

and during the Trade Test preparation

phase.

The following

indicates the

Contents of

each Section

Section 1Graphical symbols for

electrical wiring diagrams

CONTENTS

➢ Foreword

➢ Preface & Disclaimer

➢ SECTION 1: GRAPHICAL SYMBOLS FOR ELECTRICAL WIRING DIAGRAMS

1.1 Symbols and descriptions

1.2 Application in the circuit

Section 2Electrical measuring and

test instruments

CONTENTS

➢ SECTION 2: ELECTRICAL MEASURING AND TEST INSTRUMENTS

2.1 General meters (Ammeter and voltmeter in high-and low voltage circuits)

2.2 Probe tester

2.3 Multi-meter (Amps, volts, ohms and audible) Continuity

2.4 Clamp-on meter

2.5 Insulation resistance tester

2.6 Earth leakage relay/polarity tester (Combined)

2.7 Earth resistance tester

2.8 PSC and earth loop impedance tester (Combined)

2.9 kWh energy meter (Single and three-phase)

Section 3Simple circuits, diagrams

and controlling devices

CONTENTS

➢ SECTION 3: SIMPLE CIRCUITS, DIAGRAMS AND CONTROLLING DEVICES

3.1 Design and wire a circuit

3.2 One-way, two-way and intermediate switching

3.3 Three-heat and five-heat stove switches

3.4 The basic contactor and relay unit (Operations, features & application as

switching devices)

3.5 Timing relays and time switches

3.6 Overload relays

Section 4

Resistance circuit

calculations and load

balancing

CONTENTS

➢ SECTION 4: RESISTANCE CIRCUIT CALCULATIONS AND LOAD BALANCING

4.1 Current and voltage in a circuit (Kirchhoff’s first and second law)

4.2 Resistors (Series, parallel and series-parallel)

4.3 Resistors/heating elements (Balanced and unbalanced)

4.4 Three-heat stove switch with resistors

4.5 Energy metering: (Supply authority/consumer)

4.6 Energy metering: (Connect different consumer loads)

4.7 Thermostat controlled load (Blast furnace)

Section 5 Electrical motors

CONTENTS

➢ SECTION 5: ELECTRICAL MOTORS

5.1 Induction motors

5.2 Rated specifications

5.3 Name plates and terminal connections

5.4 Motor protection and overload setting

5.5 Standard three-phase motor failures

Section 6 Panel wiring (contactor control)

CONTENTS

➢ SECTION 6: PANEL WIRING (CONTACTOR CONTROL)

6.1 Single-phase motor control (Forward/reverse)

6.2 Three-phase motor control (Forward/reverse)

6.3 Three-phase motor control (Sequence start)

6.4 Three-phase motor control (Star-Delta)

Section 7Wiring of circuits

(rotary switch control)

CONTENTS

➢ SECTION 7: WIRING OF CIRCUITS (ROTARY SWITCH CONTROL)

7.1 Single-phase motor control (Forward/reverse)

7.2 Three-phase motor control (Forward/reverse)

7.3 Dual speed motor control (Separate wound arrangement)

7.4 Dual speed motor control (Pole change)

Section 8 Motor starters

CONTENTS

➢ SECTION 8: MOTOR STARTERS

8.1 Direct on line (D.O.L)

8.2 Star-Delta (Manual)

8.3 Star-Delta (Semi-automatic)

8.4 Star-Delta (Automatic)

8.5 Dual speed (Pole change)

8.6 Auto-transformer

8.7 Slip ring (Resistors as resistance)

8.8 Slip ring (Liquid as resistance)

8.9 Forward/reverse Star-Delta

8.10 Electronic soft starters

8.11 Variable speed drives

Section 9 Transformers

CONTENTS

➢ SECTION 9: TRANSFORMERS

9.1 Distribution transformer (Single-phase)

9.2 Distribution transformer (Three-phase)

9.3 Transformer calculations

9.4 Neutral earth resistor and compensator (NER/NEC)

9.5 Auto-transformer

9.6 Current transformer (CT)

9.7 Voltage transformer (VT)

9.8 CTs and VTs combined in a circuit

Section 10 Installation work

CONTENTS

➢ SECTION 10: INSTALLATION WORK

10.1 Connected and estimated load

10.2 Distribution boards, accessories and components

10.3 Bending methods for electrical conduit (Bendable metallic and non-metallic)

10.4 Conduit and wiring accessories

10.5 Wiring of different electrical circuits

10.6 Wiring of a distribution board

Section 11 Electrical tests

CONTENTS

➢ SECTION 11: ELECTRICAL TESTS

11.1 Unknown resistor circuits (‘Mystery’ box)

11.2 Single and three-phase induction motors

11.3 Phasing of a three-phase induction motor

11.4 Installation inspections and tests (To comply with the Wiring Code SANS 10142-1)

11.5 Appliance inspections and tests

Section 12Fault finding &

trouble shooting

CONTENTS

➢ SECTION 12: FAULT FINDING AND TROUBLESHOOTING

12.1 Fault finding procedure

12.2 Troubleshooting on miniature circuit breakers and earth leakage units

12.3 Troubleshooting on electrical motors

Section 13 Useful information

CONTENTS

➢ SECTION 13: USEFUL INFORMATION

13.1 Tips for trade test

13.2 Quantities, symbols and SI units

13.3 SI Prefixes

13.4 Underground cables

13.5 Select and install cable glands

13.6 Select and install earth tags

13.7 Electricity consumption table

13.8 Industrial fasteners (Standard bolts, nuts, washers & screws)

13.9 SANS symbolic safety signs

13.10 Major first aid techniques

Section 14 Summary

CONTENTS

➢ SECTION 14: SUMMARY

14.1 Formulas

14.2 General

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We hope that this South African product will bring

“electrical light” in the lives of those having a

PASSION for the electrical engineering subject!