S. Rao

Second Edition Revised by

R.K. JainFirst Edition with the assistance of

Prof. H.L. Saluja

KP

KHANNA PUBLISHERS4575/15, ONKAR HOUSE, OPP. HAPPY SCHOOL

DARYAGANJ, NEW DELHI-110002Phone : 2324 30 42 ; Fax : 2324 30 43

e-mail : khannapublishers@yahoo.inWebsite : www.khannapublishers.in

ELECTRICAL SAFETY,FIRE SAFETY ENGINEERING

&

SAFETY MANAGEMENT[A Text-Book for Engineering Students]

Published by :Romesh Chander Khannafor KHANNA PUBLISHERSNai Sarak, Delhi-110006

All Rights Reserved

[This book or part thereof cannot be translated or reproduced in any form(except for review or criticism) without the written permission of the Authorsand the Publishers.]

ISBN No. : 978-81-7409-306-6

Second Edition : 2012

Price : ` 250.00

Typesetted at : Excellent Graphics, Delhi-110053.

Printed at : Bright Printers, Pahari Bhojala, Delhi-110006.

FOREWORD

The use of electricity is essential in various domestic, commer-cial, industrial and other activities. The incidents of electric shocksand fires are rising. Awareness, education and training, and effectivesafety management have become essential during every stage of projectinstallation, testing, commissioning, operation and maintenance ofelectrical plants and appliances. By adequate precautions, the risks ofelectrical accidents can be minimized and total safety can be ensured.

With ever-increasing use of electricity, the Education andHuman Research Development in Electrical Safety Management isgaining due attention. On academic front, courses on Electrical Safetyare being introduced in the curricula. On professional Managementfront, special training courses for power engineers and electricalinspectors are being organised. There is immediate need to acceleratetraining course on Technical and Management aspects of Safety. Thisbook will pave a way for introducing such courses.

This book covers the several technical and practical topics onelectrical and fire safety and safety management. Aspects associatedwith electric shocks, fire and other accidents at construction sites andplant sites have been covered in detail. The interface between electricaldiscipline and other branches of engineering have also been coveredsystematically.

The book has a very wide coverage and gives useful practicaldata and check lists for ready use at construction sites. Attention hasbeen focussed on the significance of Safety Management and need forperfection at every stage.

It is hoped that the book will be useful as a course-material forengineering polytechnics, degree colleges and professional HRDOrganizations in Electrical Power Sector, Industry Sector, SafetyOrganizations etc.

I acknowledge my long and useful association with the Authorsin the academic and HRD field. I thank the Authors and the publishersfor the opportunity of writing this Forward and I wish all success forthis useful book on Electrical Safety.

23-10-98 Dr. S.D. VarwandkarMumbai M.E. (Elect), Ph. D. (IIT, Kanpur)

Professor and Head,Electrical EngineeringVJTI, Mumbai, 19

( iv )

PREFACE

Electricity is essential in modern life, both at home and on thejob. Some engineers, electricians, technicians, and workers work withelectricity directly. Others work with it indirectly. Electricity hasbecome such a familiar part of our daily life, many of us don’t givemuch thought to how much our work depends on a reliable source ofelectricity. More importantly, we tend to over look the hazardselectricity poses and fail to treat it with the respect it deserves.

Electricity has long been recognized as a serious workplacehazard, exposing employees to electric shock, electrocution, burns,fires, and explosions.

Managements of Industrial and Electrical Plants and Consumersof electricity tend to neglect safety aspects at the risk personnel. Acasual glance at some electrical installation reveals need of essentialsafety measures such as a fence, a good earthing system, cleaninsulators, well dressed cables and clean surroundings.

With ever-increasing use of electricity by domestic, industrial,commercial, agricultural/rural and other consumers, the safety ofpersonnel, plant and equipment is gaining due attention.

Electricity is a very safe and easily controllable form of energyonly if the installations, plant and equipment are built with adequatesafety precautions and users are aware and follow safety rules in everyaction. Safety Principles, Rules and Acts, Procedures have beendocumented during the 20th century for use at Project Sites, Plant Sitesand in Consumers Premises.

Safety Management and Safety precautions are necessary atevery stage, (design of plant and equipment, manufacture ofequipment and components, testing, dispatch, site construction work,(Erection/testing/commissioning), operation and maintenance (O andM) of electrical plants/equipment and casual use of electricity).

The risks include Electric shocks, fires and explosions, fall ofobjects on head, fall of persons from height, flashovers and faultsin equipment and machines, etc. Accidents and fires result in injuries,loss of life and loss property.

The accidents occur due to unsafe conditions are unsafepractices and unsafe acts, lapse of management, unawareness ofindividuals, lack of training, lack of procedures and carelessness.Behind every accident there are several chance misses.

Accidents can be completely eliminated by following SafetyPrinciples and Procedures. Management, Supervisors and Technicianshave obligation towards safety and prevention of accidents and loss.Management should be committed to safety. Safety should beorganized and managed.

This book will be found useful for the Students of Final YearDiploma Courses and Post-Diploma Courses on Safety for variousdisciplines of Engineering. The book forms a single semester coursefor B.E. courses in Electrical/Electronics, Mechanical, Civil, Chemical,Energy and other disciplines. This book will also serve as a coursematerial for training courses for Electrical Supervisors and ElectricalInspectors.

This book will serve as a course material for HRD Coursesorganized by National Safety Council, Central Power ResearchInstitute, National Power Training Institute, Indian Bureau ofStandards, Power Grid Corporation, NTPC, NHPC and State andPrivate Electrical institutes.

The book is backed by field experience of the Authors with HighVoltage AC, EHV, AC, HVDC, Traction Substation, Rectifier PlantSites, Power Plants, High Voltage testing, Short Circuit Testing,Environmental Testing, First Aid, Fire Fighting Systems and InsuranceSurveys, Investigations of electrical accidents and fires, HRD courseson Electrical and Industrial Safety.

We express our sincere thanks and gratitude to organisationlike CEF, BHEL, NTPC, NPCL, PGCIL, Bangalore Electrical SupplyCo. Ltd, NDPL, etc. whose literature has been consulted in completingthe manuscript of this book. We thank Shri Vineet Khanna,M/s Khanna Publishers and their Staff for speedy release of thispublication.

Request to Readers. The comments and suggestions on subjectmatter and any facet of this new book are eagerly awaited. They willbe gratefully acknowledged.

—AUTHORS

( vi )

CONTENTS

Chapter Pages

1. Introduction to Electrical Safety andSafety Management 1—341.1. General Background of Electricity ............................................ 11.2. General Safety Provisions in Indian Electricity Rules .......... 31.3. OSHA Standards on Electrical Safety ...................................... 61.4. Basic Electrical Safety Rule as per OSHA ............................... 61.5. Terms and Definitions ................................................................. 71.6. Objectives of Safety and Security Measures ........................... 91.7. Hazards Associated with Electric Current and Voltage ...... 91.8. Protection against Electrical Hazards .................................... 111.9. Who is Exposed ? ....................................................................... 111.10. Three Types of Electrical Hazards .......................................... 131.11. Effect of Electrical Current on the Human Body ................ 131.12. What are Accidents ? ................................................................. 141.13. Immediate Action to Recover the Patient

in Case of Accidents .................................................................. 151.14. Principles of Electrical Safety .................................................. 161.15. Approaches to Prevent Accidents ........................................... 181.16. Scope of Subject ‘Electrical Safety’ ......................................... 201.17. Fire Prevention and Fire Fighting .......................................... 20

Summary ....................................................................................... 31Solved Questions ........................................................................... 31Questions ....................................................................................... 34

2. Electrical Shocks and their Prevention 35—622.1. Primary and Secondary Electric Shocks ................................ 352.2. Occurrence of Electric Shock ................................................... 352.3. Possibility of Getting Electric Shock ...................................... 37

2.3.1. Shocks from 3 Phase AC System ............................... 372.3.2. Shocks from Bipolar DC System ................................ 39

2.4. Severity of Electric Shock ......................................................... 392.5. Medical Analysis of Electric Shock and Its Effects ............. 432.6. AC Shocks Versus DC Shocks ................................................. 452.7. Effect of Impulse Discharge through Human Body ........... 46

( ix )

Chapter Pages

( x )

2.8. Shocks Due to Flashovers/Spark-overs ................................. 472.8.1. Dangers from Sparkover/Flashover ......................... 472.8.2. Internal and External Flashovers ............................... 482.8.3. Flash Burns ..................................................................... 482.8.4. Electrical Arc Blasts ...................................................... 48

2.9. Lightning Strokes on Overhead Transmission Linesand Outdoor Substations .......................................................... 50

2.10. Prevention of Shocks ................................................................. 512.11. Safety Precautions against Contact Shocks,

Flash Shocks and Burns ............................................................ 512.12. Safety Precautions in Small LV Installations,

Residential Buildings, Shops ................................................... 522.13. Safety Procedures in Electrical Plant ..................................... 522.14. Installation of Earthing System ............................................... 562.15. Sequence of Operation of Circuit-breaker, Isolator

and Earthing Switch .................................................................. 56Summary ....................................................................................... 58Solved Questions ........................................................................... 58Questions ....................................................................................... 61

3. First AID 63—783.1. Introduction ................................................................................. 633.2. Removal of Contact with Live Conductor ............................ 633.3. First Principles of Actions After Electric Shock ................... 633.4. Artificial Respiration ................................................................. 643.5. Schafer’s Prone Pressure Method ........................................... 653.6. Silvester’s Method ...................................................................... 663.7. Nielson’s Arm-lift Back-pressure Method ............................ 663.8. Mouth to Mouth Method .......................................................... 673.9. Use of Artificial Resuscitator ................................................... 683.10. External Cardiac Massage ........................................................ 693.11. Cardiac Pulmonary Resuscitation ........................................... 703.12. Chocking ...................................................................................... 703.13. Poisoning ..................................................................................... 713.14. Open Wounds ............................................................................. 713.15. Control of Bleeding .................................................................... 723.16. Heavy Bleeding .......................................................................... 723.17. Shock ............................................................................................. 723.18. Burns and Scalds ........................................................................ 72

Chapter Pages

( xi )

3.19. Fractures and Dislocations ....................................................... 743.20. Snake Bite .................................................................................... 753.21. Heat Exhaustion ......................................................................... 753.22. Heat Stroke .................................................................................. 763.23. Accident Management and Safety Management ................. 76

Summary ....................................................................................... 77Solved Questions ........................................................................... 77Questions ....................................................................................... 79

4. Equipment Earthing (Grounding) and SystemNeutral Earthing 80—1104.1. Introduction ................................................................................. 804.2. Distinction between System Grounding

(Neutral Grounding) and Equipment Grounding ............... 804.3. Associated Safety Systems in Electrical Installations ......... 814.4. Equipment Earthing (Body Earthing, Safety Earthing) ...... 834.5. Total Earthing System in Electrical

Substation/Electrical Plant ....................................................... 854.6. Functional Requirements of Earthing System ...................... 854.7. Description of an Earthing System ......................................... 884.8. Technical Consideration of Station Earthing System ......... 924.9. Procedure of Laying Earthing-Mat ......................................... 944.10. Step Potential And Touch Potential ....................................... 964.11. Neutral Grounding (System Grounding) .............................. 994.12. Stable Neutral Point Due to Neutral Earthing ................... 1024.13. Freedom From Arcing Ground/Repeated Overvoltages . 1034.14. Types of Grounding ................................................................ 1044.15. Methods of Earthing Generators Neutrals .......................... 1044.16. Circuit Protection Devices ...................................................... 1044.17. Protection against Energised Metal Parts ........................... 105

Summary ..................................................................................... 105Solved Questions ......................................................................... 105Questions ..................................................................................... 110

5. Safety—Clearances and Creepage Distances inElectrical Plant and Equipment 111—1235.1. Introduction ............................................................................... 1115.2. Some Terms and Definitions ................................................. 1125.3. Clearances (Insulating Distances) ......................................... 114

Electrical Safety, Fire Safety Engineeringand Safety Management

Publisher : KHANNAPUBLISHERS ISBN : 9788174090258 Author : S. Rao, R. K. Jain

and H. L. Saluja

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