BS-5733-1979.pdf

BRITISH STANDARD BS 5733:1979 (Reprinted, incorporating Amendments No. 1 to No. 3 inclusive) Specification for General requirements for electrical accessories UDC 621.316.08:621.316.172 Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 15:00:07 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5733:1979 This British Standard, having been prepared under the direction of the Power Electrical Engineering Standards Committee was published under the authority of the Executive Board and comes into effect on 30 April 1979 © BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference PEL/4 Draft for comment 74/25539 DC ISBN 0 580 10739 6 Cooperating organizations The Power Electrical Engineering Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Associated Offices Technical Committee Association of Short Circuit Testing Authorities* British Electrical and Allied Manufacturers Association (BEAMA) British Railways Board British Steel Corporation Department of Energy (Electricity) Electrical Contractors Association* Electrical Contractors Association of Scotland Electrical Research Association* Electricity Supply Industry in England and Wales* Engineering Equipment Users Association Institute of Purchasing and Supply Institution of Electrical Engineers* Ministry of Defence National Coal Board National Economic Development Office* Trades Union Congress The organizations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard: Association of Consulting Engineers Association of Supervisory and Executive Engineers British Electrical Systems Association (BEAMA) British Plastics Federation Consumer Standards Advisory Committee of BSI Department of Prices and Consumer Protection Electrical Association For Women Department of the Environment (PSA) Electrical Installation Equipment Manufacturers Association (BEAMA) Electrical Power Engineers Association Electricity Consultative Councils Fire Offices Committee Lighting Industry Federation Limited National Inspection Council For Electrical Installation Contracting Amendments issued since publication Amd. No.Date of issueComments 3661October 1981 4197July 1983 5107June 1986Indicated by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 15:00:07 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5733:1979 © BSI 08-1999i Contents Page Cooperating organizationsInside front cover Forewordiii Section 1. General 1Scope1 2References1 3Definitions1 4Service conditions2 5General requirements2 6Marking3 Section 2. Specific requirements 7Materials4 8Enclosures4 9Creepage distances and clearances5 10Precautions against electric shock5 11Precautions against reversal of polarity6 12Separation of terminals and conductors6 13Provision for earthing6 14Connections between current carrying parts7 15Terminals7 16Flexible cords or cables8 17Switch action8 18Resistance to abnormal heat and to fire8 19Mechanical strength8 20Insulation strength9 21Current rating9 22Resistance to moisture9 Section 3. Methods of test 23General conditions for the tests9 24Type tests9 25Insulation resistance test9 26Electric strength test10 27Temperature rise and voltage drop at rated current test10 28Moisture resistance test11 29Resistance to heat test11 30Cord grip test12 31Socket contacts and shutters test12 32Resistance to abnormal heat and to fire test13 33Mechanical strength test14 34Resistance to rusting test15 Appendix A Principles for test of insulating parts of accessories22 Figure 1 Glow-wire with thermocouple16 Figure 2 Glow-wire test apparatus17 Figure 3 Pendulum impact test apparatus18 Figure 4 Constructional details of striking element18 Figure 5 Mounting support for test samples19 Figure 6 Ball pressure test apparatus19 Figure 7 Apparatus for pressure test on plugs and portable socket-outlets20 Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 15:00:07 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5733:1979 ii © BSI 08-1999 Page Figure 8 Tumbling barrel21 Table 1 Creepage distances and clearances6 Table 2 Terminal screws: size and torque7 Table 3 Cross-sectional areas of cable conductors for tests of temperature rise and voltage drop10 Table 4 Cross-sectional areas of conductors in flexible cords for tests of temperature rise and voltage drop11 Table 5 Torque for test of cord grip12 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 15:00:07 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5733:1979 © BSI 08-1999iii Foreword This British Standard has been prepared under the direction of the Power Electrical Engineering Standards Committee. Previously requirements for accessories were specified together with requirements for appliances, in BS 816. However, appliances are now covered by BS 3456 “Specification for safety of household electrical appliances”. Similarly, lighting fittings have now been covered by BS 4533 “Electric luminaires (lighting fittings)” and other British Standards. Since the publication of BS 816 in 1952, various tests have been developed in order to assess more completely the suitability of an item of electrical equipment for its purpose, and it became necessary to prepare a new standard to include these tests but with its scope limited to accessories. This has now been done in this standard. This new standard comes into force immediately but, to allow manufacturers time to design and introduce any necessary changes, BS 816 will not be withdrawn until twelve months from the date of publication of this standard. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 22, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 15:00:07 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 15:00:07 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5733:1979 © BSI 08-19991 Section 1. General 1 Scope This British Standard specifies requirements for electrical wiring accessories for installation purposes, and for associated plugs and portable accessories including cable reels, not specifically covered by current British Standards, which are designed for use in single-phase a.c. or d.c. circuits in which the voltage between conductors exceeds extra low voltage (Band 1) and does not exceed 250 V a.c. or d.c. and the rated current does not exceed 45 A. This standard does not apply to electronic devices, or to plug-in devices incorporating timers, thermostats, transformers, etc. It does not apply to accessories intended primarily for industrial use. 2 References The titles of the publications referred to in this standard are listed on the inside back cover. 3 Definitions For the purposes of this British Standard the following definitions apply. 3.1 accessory a device associated with the wiring of an installation 3.2 adaptor an accessory for insertion into a socket outlet and containing metal contacts, to accommodate one or more plugs 3.3 rated voltage the voltage marked on the accessory, which can be either a voltage range (e.g. 230 V to 250 V) or a single voltage (e.g. 240 V) 3.4 maximum rated voltage the higher of the two voltages mentioned in 3.3 or the single marked voltage 3.5 rated current the current marked on the accessory or that current stated by the manufacturer as the current the accessory will carry under prescribed conditions 3.6 actuating member that part which is moved, pulled, pushed or turned by the user to operate the mechanism of a switching device 3.7 live parts current carrying parts, and those metal parts in contact with them during normal service. Earthing terminals are not considered to be current carrying parts 3.8 pillar terminal terminal in which the conductor is inserted into a hole or cavity, where it is clamped by the screw or screws. The clamping pressure may be applied directly by the end of the screw or through an intermediate clamping member to which pressure is applied by the end of the screw 3.9 screw terminal terminal in which the conductor is clamped under the head of a screw. The clamping pressure may be applied directly by the head of the screw or through an intermediate part, such as a washer, clamping plate or anti-spread device 3.10 stud terminal terminal in which the conductor is clamped under a nut. The clamping pressure may be applied directly by a suitably shaped nut or through an intermediate part, such as a washer, clamping plate or anti-spread device 3.11 saddle terminal terminal in which the conductor is clamped under a saddle by means of two or more screws or nuts 3.12 lug terminal terminal designed for clamping a cable lug or bar by means of a screw or nut 3.13 mantle terminal terminal in which the conductor is clamped against the base of a slot in a threaded stud by means of a nut, by a suitably shaped washer under the nut, by a central peg if the nut is a cap nut, or by an equally effective means for transmitting the pressure from the nut to the conductor within the slot 3.14 plug an accessory intended for connection to a flexible cord or cable which can be engaged manually with a socket outlet, and which has current carrying pins which may be exposed when not engaged Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 15:00:07 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5733:1979 2 © BSI 08-1999 3.15 shutter a movable device comprising one or more components intended to provide automatically an insulating screen to protect live contacts of accessories from access which would otherwise be exposed when a cooperating device is withdrawn when not in normal use 3.16 fixed accessory an accessory designed to be part of, and permanently connected to, a fixed installation 3.17 portable accessory an accessory designed for use other than as part of a fixed installation 3.18 extra low voltage (elv) a voltage which does not exceed 50 V a.c. r.m.s. between conductors, or between any conductor and earth NOTEThe appropriate d.c. voltage is under consideration. 3.19 tool a screwdriver, a coin or any other object that may be used to operate a screw or similar fixing means 3.20 micro-gap switch any switch which is designed and constructed to operate with clearances between the contacts less than the values specified in clause 9, irrespective of the speed of operation of the contacts 3.21 glow-wire a specified loop of resistance wire which is electrically heated to the required test temperature 3.22 test temperature the temperature to which the glow-wire is heated 3.23 application time the time during which the glow-wire is applied to the test specimen 3.24 test specimen hereinafter referred to as specimen. An electrical accessory or suitable part cut from it 3.25 cable reel an assembly comprising a plug and a socket-outlet connected together by a length of flexible cord and having provision for winding the cord onto a reel, the socket-outlet being attached to or integral with the reel 4 Service conditions The accessories shall be suitable for use under the following conditions of service. a) An ambient temperature having a peak value not exceeding 40 °C, with an average value not exceeding 35 °C in a period of 24 h, but not subject to exposure to direct radiation from the sun or any other source of heat likely to raise the temperature above the specified ambient temperature. b) An ambient temperature having a value not less than 5 °C c) An altitude not exceeding 2 000 m above sea level. d) An atmosphere not subject to excessive pollution by smoke, chemical fumes, salt laden spray, prolonged periods of high humidity or other abnormal conditions. NOTEUnder normal conditions of service the available cooling air is subject to natural atmospheric variations of temperature and hence the peak temperature occurs only occasionally during the hot season and, on those days when it does occur, it does not persist for lengthy periods. Meteorological records indicate that temperatures of at least 10 °C below the peak temperature will occur within the 24 h period and that the average temperature will be at least 5 °C below peak value. 5 General requirements 5.1 Accessories shall be so designed and constructed that in normal use they function reliably and cause no danger to persons or surroundings when installed in the proper manner. Compliance with the requirements of this standard shall be checked by carrying out all the relevant tests specified. 5.2 Where the standard is used for the purpose of granting nationally recognized certification marks, the designs or constructions, to which the tests specified cannot be precisely applied but which give an equivalent degree of safety and durability of safety may be regarded as complying with the requirements of this standard, subject to the findings of a special investigation by the authority granting the certification mark and pending the issue of an amendment or extension to this standard. Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 15:00:07 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5733:1979 © BSI 08-19993 5.3 Where tolerances are not specified in this standard, the quantities are to be regarded as nominal. 5.4 Accessories incorporating plug pins and/or socket contacts, intended to engage with socket-outlets or plugs complying with other British Standards, shall be so designed and constructed that such plug pins and/or socket contacts comply with these British Standards, with regard to their dimensions, configuration, other requirements and tests. Compliance shall be checked by inspection and measurement. 6 Marking 6.1 Every accessory shall be marked with the following. a) The name or trade mark of the manufacturer or responsible vendor. b) The number of this British Standard, i.e. BS 57331). Where applicable, accessories shall also be marked with the following. c) Rated current in amperes. In the case of cable reels the rated current shall have two values: 1) for the cord in its fully reeled condition; 2) for the cord in its fully unreeled condition. d) Rated voltage in volts. e) Symbol for nature of supply, if the accessory is not intended for both a.c. and d.c. or if the rating is different for a.c. and d.c. NOTEIn the case of cable reels, this marking is only re