Disclosure to Promote the Right To Information

Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public.

इंटरनेट मानक

“!ान $ एक न' भारत का +नम-ण”Satyanarayan Gangaram Pitroda

“Invent a New India Using Knowledge”

“प0रा1 को छोड न' 5 तरफ”Jawaharlal Nehru

“Step Out From the Old to the New”

“जान1 का अ+धकार, जी1 का अ+धकार”Mazdoor Kisan Shakti Sangathan

“The Right to Information, The Right to Live”

“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता है”Bhartṛhari—Nītiśatakam

“Knowledge is such a treasure which cannot be stolen”

“Invent a New India Using Knowledge”

है”ह”ह

IS 9409 (1980): Classification of electrical and electronicequipment with regard to protection against electric shock[ETD 1: Basic Electrotechnical Standards]

IS : 9409 - 1980

Indian Standard :: CLASSIFICATION OF

ELECTRICAL AND ELECTRONIC EQUIPMENT WITH REGARD TO PROTECTION

AGAINST ELECTRIC SHOCK

Electrotechnical Standards Sectional Committee, ETDC 1

Chairman Representing

SHRI J. S. ZAVERI Bharat Bijlee Ltd, Bombay; and Rotating Machi- nery Sectional Committee, ETDC 15, ISI

Members

SHRI H. V. BADRINATH Wireless Planning and Coordination Wing,

SHRI V. K. BATRA Ministry of,Communications, New Delhi

Natgee;;: PhysIcal Laboratory ( CSIR ), N~A

SHRI T. L. BHATIA Indian Posts and Te!egrsphs Department

SHR~ J. M. NEOOY ( Alternate ) ( Ministry of Communications ), New Delhi

SHRt V. S. BHATIA LOW Voltage Switchgear and Controlgear Sec-

&to N. DAYAL tional Committee, ETDC 57, IS1

COL K. V. KUDVA ( Alternate ) Ministry of Defence ( DGI ), New Delhi

DIRECTOR ( TED ) Central Electricity Authority ( Department of Power, Ministry of Energy ), New Delhi

DEPUTY DIRECTOR ( TED ) ( Alternate ) SHRI M. L. Do NGRE how;;* Cables Sectional Committee, ETDC 59,

SHRI R. D. JAIN Conductors and Accessories for Overhead Lines

SHRI K. C. KAUL Sectional Committee, ETDC 60, ISI

SHRI PRAKAYH SINGH ( Alternate ) Bharat Heavy Electricals Ltd, Bhopal

SHRt S. K. MUKHERJEE National Test House, Calcutta SHRI B. MUKH~PADHYAY ( Alternate )

PROF R. C. NARAYANAN General Nomenclature and Symbols Subcom-

SHRI D. V. NARKE mittee, ETDC 1 : 3, IS1

Transformers Sectional Committee, ETDC 16, IS1

( Continued on page 2 )

@ Copyright 1980 INDIAN STANDARDS INSTITUTION

This publication is protected under the Indian Copyright Act ( XIV of 1957 ) and

I

reproduction in nhole or in part by eny means except with written permission of the publisher shall be deemed to be an infringement of copyright under the said Act.

1s:9409-1980

( Continuedfrom page 1 )

hknberr

SHRi H. M. PAI

%RI R. RADHAKRISHNAN

Representing High Voltage Switchgear and Controlgear Sec.

tional Committee, ETDC 58, IS1 Central Electrochemical Research Institute

( &RI H, N. VENKOBARAO ( Alternate )

CSIR ), Karaikudi

SHRI T. S. M. RAO Relays Sectional Committee, ETDC 35, ISI SBRI V. L. SASTRY Electronics and Radar Development Establish*

meot ( Ministry of Defence ), Bangalore SHRI K. V. BHAT ( Attevriate )

DR S. M. SEN Institution of Engineers ( India ), Calcutta DR H. V. K. UD~JPA Secondary Cell8 and Batteriek Sectional Com-

mittee, ETDC II, ISI SI~RI M. P, WAGAH Indi;~m~a~ctricaI Manufacturers’ Association,

’ SHRI S. D. MED~~~KAR ( Alfernnate > SHRI S. P. SACHDEV, Director General, IS1 ( B-ofieio bciember )

Director ( Eleo tech ) ( SecrCraFy )

2

Indian Standard

IS :9409 - 1980

CLASSIFICATION OF ELECTRICAL AND ELECTRONIC EQUIPMENT

WITH REGARD TO PROTECTION AGAINST ELECTRIC SHOCK

I 0. FOREWORD

0.1 This Indian Standard was adopted by the Indian Standards Institution on 23 January 1980, after the draft finalized by the Electrotechnical Standards Sectional Committee had been approved by the Electrotechnical Division Council.

0.2 This standard marks an important step towards the unification of low- voltage ele%rical and electronic equipment and covers a wide range of applications in homes, offices, workshops, farms, etc, as well as for medical and dental purposes.

0.3 While laying down in a uniform way the different classes of protection against electric shock, this standard also gives the terms used in the descrip- tion of the classes.

0.4 This standard is intended to give guidance on the classification of low- voltage electrical and electronic equipment intended for connection to an external po.wer supply with regard to protection against electric shock in the event of an insulation failure. According to this classification, this protec- tion may be provided by the environment, by the equipment itself or by the system of supply, and these aspects are summarized in Appendix A.

0.5 Protection with regard to other aspects is covered in other Indian Standards, for example, degrees of protection by enclosures are given in IS : 2147- 1962” and IS :4691 - 1968t.

0.6 This standard is based upon experience with voltages up to 440 V rms and 250 V rms between phases and earth in equipment designed for the purposes detailed in 1. However, the possibility of using it for higher vol- tages and other purposes may be considered.

*Degrees of protection provided by enclosures for low-voltage switchgear and controlgear.

iDegrees of protection provided by enclosures for rotating electrical machinery.

3

IS: 9409 -1980

0.7 Attention is drawn to the fact that the classification and the related definitions have been carefully coordinated and although only parts may be necessary for a particular item of work, such parts as are used should not be altered in introducing them into other standards.

0.8 Tn the preparation of this standard, assistance has been derived from IEC Pub 536 ( 1976 ) Classification of electrical and electronic equipment with regard to protection against electric shock, issued by the International Electrotechnical Commission.

1. SCOPE

1.1 This standard describes classification with definitions for protection against electric shock in the event of failure of the insulation, It does not detail the requirements for design, construction and testing according to this system.

1.2 This classification applies to electrical and electronic equipment ( but not the components thereof ) intended for connection to an external power supply at system voltages not exceeding 440 V rms and 250 V rms between phases and earth, for use by the general public in homes, ofices, workshops, schools, farms and the like, and for medical and dental purposes.

1.3 Open-type equipment, that is to say, equipment which do not of them- selves provide the required degree of protection against contact with live parts are not covered.

2. DEFINITIONS

2;O For the purpose of this standard, the following definitions shall apply.

2.1 Basic Insulation - Insulation applied to live parts to provide basic prc* tection against electric shock.

NOTE - Basic insulation does not necessariIy include insulation used exclusive- ly for functional purposes.

2.2 Supplementary Insulation - Independent insulation applied in addition to basic insulation in order to provide protection against electric shock in the event of a failure of basic insulation.

2.3 Double Insulation - Insulation comprising both basic insulation and supplementary insulation.

4

IS :9409 -1980

2.4 Reinforced Insulation - A single insulation system applied to live parts, which provides a degree of protection against electric shock equiva- Il:nt to double insulation under, the conditions specified in the relevant standard.

NOTE - The term ‘ insulation system ’ does not imply that the insulation shall be one homogeneous piece. It may comprise several layers which may not be tested singly as supplementary or basic insulation.

2.5 Safety Impedance - An impedance connected between live parts and accessible conductive parts, of such value that the current, in normal use and under likely fault conditions in the equipment, is, limited to a safe value, and which is so constructed that the reliability is maintained through- out the life of the equipment.

NOTE - Details of the likely fault conditions, the safe current and tho require- ments for reliabijity are as given in the relevant standards.

2.6, Safety Extra-Law Voltage ( SELV ) - A voltage which does not exceed 50 V ac rms ( see Noie 1 ) between conductors, or betwe;en any conductor and earth,. in a circuit which is isolated from the supply mains by means of a safety isolating tr&fortier or converter with separate windings. .I NOTE 1 - The dc v&z is tinder donsideration. . . .’

* NQTEZ- Limitation to voltages lower than 50 V gq rms may be specified in the particular stabdard, especially whfn direct co*ttact with live palts 16 mvolycd.

NOTE 3 - The. ‘voltage lipit should not be exceeded. either .at full load or no-load, but it, is assumed, for the d&pose o i this d&nition,‘that any transformer oi converter’ is operated at its rated supply voltage,, . . .;

3; _CLASSES OF EQUIPMENT

3.0 The class numbers are not intended to reflect the safety level of the equipment, but ,only the means by which the safety is obtained.

, :s ’ I 1 3.1 Class 0 Equipment - Equipment in ‘which prote&n agwt elegtric shock relies upon basic insulation; this implies that there are no means for the cotinection of accessible condut%ive parts; if any, to’ the protectivF;con- ductor in the fixed wiring of the installation, reliance in the H&t of a failure of the basic insul,ation bein+ placed upon the environment.

‘. ,

3.2 Class I Eqiipment - Equip&&? in &c)h protection against electric shock does not rely on basic insuiation only, but #ich,includes an additio- naj ,:safety_ ,precautidh in ,such a way ‘that_ .means are provided for the connection of accehsi’ble conductive p&t& to thc.pmtcctilvc ( earthing ) con- ductor in the fixed wiring of the installation in such a way that accessible

5

IS :.9409 - 19801

conductive parts may not become live -in ,the*event of a failure of (he basic insylation. : ,,

3’ ._ NOTE I._ For eqtiipment intended for use%vith.a flexible-cord or cabi+e, this pie- vision includes a protective conductor as part of the flexible cord or cable. . ‘:

.~OTB 2-Where equipment designed .as..Clas$ &,is. allowed to be fitte$ with d $wo-core ‘flexible cord or ,cable provided that it is fitted with a plug yh,ich day ,n,ot bb infroduced ?nto a socket outlet wi,t,h darthi contact,, the protectlon 1s: th3n equivalent to that of Class 0. but’ tl% eirthing provlsl6ns oT the equipment in all other respects she@ fully comply wit,h the requirements of Class I.

.> a .s , : a . .

3.3 fiYrss II Eq&ment - Equipmknt in yvhicb prdtiction against eJectr$, s&k does not raly on basic iii@afion only% $ut in, whi,cb ad&t&al saTe{y precautions sutih’.as double insulation br reinforckd Insulation are proviE: ed, there being no provision for protective earthing or reliance upon instlliation donditions.

Nora 1 - In certaii’ dp&ial c&s, &h as’the signal terminals of electronic cc#pment. safety impedance may be used W Class .I1 equipment where it, has been

‘is&blished- that the safety impedance is necessary and that,, the technique may !%d >included. without ‘dettiment:to’the’$afety l_evel.

1: ?

NOTB 2 & Chss II equippent, may be,’ piovided Gjth means for maintaih& the contindtjr of protbctive ci’rc&ts: provided that such ineans are’withib the equipment and are insulated from,,accessible.surfaces according to the requirements of Claus II.

NOTE ‘3 -, In certpin cases, ‘it may be .riecessa& t? gistingtijsh. ,bet\n/een ‘$1 inru!ated’ and ‘metal-encased’ Class ?I &jui$ment.

NOTE 4 -Metal-encased C&s II equipment may be provided with means -for the connection of a potential equalization conductor to the enclosure only where such a need is recognized in the relevant standard.

/

Noms- Class II equipment may be prov’ ed with means .for conne+on_ to_ s, earth for functional ( as distinct from protect1

is recugniztd in the relevant standard. ) purposes only where such a need’

, ‘ ~ “I

3.4 Class IIF Equipment - Equipment in which proZtction agaitist electric shock relies on supply at safety extra-low voltage ( SELV) and in which voltages highcr;than%ho’se of.SBLV are not] ge&ated. ‘..I 4’ “ ’

i’ ,’ ,I!.I.! 4 1 I , ‘I ‘Nowi* + Class III equipment should not be’ provided with ame&ns for protective,, &thing. f .,

Nom 2’ “’ Meraf:enc!ased Cl&s’111 eqaivment’ may bb’ providsd’w%ti me&’ for the connection of a potential equalization cqnductor to the enclosure only where

‘such a necd?s recogbize&& the.&eyanr sta?&rd. i,” 1 g . ‘ ,, .o:

Ndh 3 Y-&&s III e&&mdnt ‘mldy”be’!&dilihe& ‘tiith means f& cb~nec~iori * to earth for fhnc’tional ( as distinct- ‘from protective’) purpo@’ ohl); wheie buch ‘a :’ mad is recdgnized in the relevant standard’ - I J i “I .‘. ,I:: Id*. )‘. _. .

‘6.‘. *‘I .I -.> .u

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IS :9409 - 1980

APPENDIX A

( Clause 0.4 )

PRINCIPAL CHARACTERISTICS OF EQUIPMENT AND PRECAUTIONS FOR SAFETY

A-l, EQUIPMENT CHARACTERISTICS AND SAFETY PRF CAUTIONS

A-1.1 - Table 1 gives the principal characteristics of equipment according to this classification and indicates the precautions necessary for safety in thr event of a failure of the basic insulation.

TABLE 1 EQUIPMENT CHARACTERISTICS AND %WETY PRECAUTIONS

CLASS 0 CLASS 1 CLASS 11 cuss III

Principal No. means Protective earth- A d d i t i o n a I character- for protec- ing means are insulation and

D$ndt for sup- safety

istics of tive earth- provided no means for extra-low voltage the equip- inp protective ment earthing

Precautions Earth-free Connection to None necessary Connection to for safety environ- the protective safety extra-low

ment earthing voltage

INDIAN STANDARDS

ON

ELECTROTECHNICAL STANDARDS

IS :

585-1962 Voltages and frequency for ac transmission and distribution systems ( revised )

3599-1966 Method of measurement of cooling medium temperature for electrical apparatus

3722-1966 Letter symbols and signs used in electrical technology

7691-1975 Frequencies for special power applications 8270 ( Part I )-1976 Guide for preparation of diagrams, charts and tables

for eIectrotechnoIogy: Part I Definitions and classification 8270 ( Part II )-1976 Guide for preparation of diagrams, charts and tables

for electrotechnology: Part II Item designation

8270 4 Part III )-I977 Guide for preparation of diagrams, charts and tables for electrotechnology: Part III General requirements for diagrams

8270 ( Part IV )-1977 Guide for preparation of diagrams, charts and tables for electrotechnology: Part IV Circuit diagrams

8270 ( Part V )-1976 Guide for preparation of diagrams, charts and tables for electrotechnology: Part V Interconnection diagrams and tables