Basic Electrical Installation Calculations

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Basic Electrical Installation Calculations

Introduction

Basic Electrical Installation Calculations

    Being able to carry out mathematical calculations is a vital part of electrical installation courses and indeed electrical installation work. 

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    The structure of electrical installation courses continually changes as do the course titles and numbers; however, electrical science remains the same and, like it or not, anyone wanting to become an electrician will need to have a good understanding of how to carry out electrical calculations.

    The calculations which need to be performed vary from those which an electrician needs almost on a daily basis, such as cable calculation or the amount of energy required to run a particular piece of equipment, to more complex calculations such as those required for electromagnetism.

DESIGN OF ROTATING ELECTRICAL MACHINES

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Table Of Contents

1 Use of Calculators 1

2 Simple Transposition of Formulae 3

3 SI Units 5

• SI derived units (used in Book 1 & 2) 6
• SI unit prefixes 7

4 Conductor Color Identification 9

5 Circuit Calculations 11

• Ohm’s law 11
• Resistors in series 14
• Resistors in parallel 18
• Calculation of total resistance of resistors in parallel 20
• Resistances in parallel using product over sum method 21
• Series and parallel resistors 26

6 Voltage Drop 29

• Conductor resistance and voltage drop using
• Ohm’s law 29
• Voltage drop using tables from BS 7671

7 Areas, Perimeters and Volume 33

• Calculation of perimeters 33
• Areas and Perimeters 34
• Volumes 36

8 Space Factors 41

9 Coulombs and Current Flow 53

10 Internal Resistance 55

• Resistivity 55

11 Power in a d.c. and Purely Resistive a.c. Circuit 67

• Mechanics 78
• Mass, force and weight 80
• Efficiency 92

12 Power Factor 99

• kVA, kVAr and kW 99

13 Transformers 103

• Transformer calculations 103

14 Electromagnetic Effect 107

• Magnetic flux and flux density 107
• Force on a current carrying conductor within a magnetic field 108

15 Induced e.m.f.

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