1、BRITISH STANDARD BS 7462:1991 Specification for Electrical safety of domestic gas appliancesBS7462:1991 This British Standard, having been prepared under the direction of the Gas Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 29 November
2、 1991 BSI 02-2000 The following BSI references relate to the work on this standard: Committee reference GSE/17 Draft for comment 89/79516 DC ISBN 0 580 19817 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Gas Standards Policy Committe
3、e (GSE/-) to Technical Committee GSE/17, upon which the following bodies were represented: Association for Consumer Research (ACRE) British Gas plc Consumer Policy Committee of BSI Department of Energy (Energy Efficiency Office) Department of the Environment (Construction Directorate) Department of
4、Trade and Industry (Consumer Safety Unit, CA Division) Gas Consumers Council Institution of Gas Engineers Liquefied Petroleum Gas Industry Technical Association (UK) National Caravan Council Limited Royal Society for the Prevention of Accidents Society of British Gas Industries Amendments issued sin
5、ce publication Amd. No. Date CommentsBS7462:1991 BSI 02-2000 i Contents Page Committees responsible Inside front cover Foreword iii 1 Scope 1 2 Definitions 1 3 General requirements 3 4 General conditions for the tests 3 5 Rating 4 6 Classification 4 7 Marking 4 8 Instructions 6 9 Protection against
6、electric shock 9 10 Starting of motors 11 11 Input and current 12 12 Temperature limits 12 13 Leakage current and dielectric strength at operating temperature 13 14 Moisture resistance 15 15 Insulation resistance and electric strength 19 16 Overload protection 20 17 Motors 21 18 Stability and mechan
7、ical hazards 22 19 Mechanical strength 22 20 Construction 23 21 Internal wiring 25 22 Components 26 23 Supply connection and external flexible cables and cords 27 24 Terminals for external conductors 32 25 Provision for earthing 35 26 Electrical connections and screws 35 27 Creepage distances, clear
8、ances and distances through insulation 37 28 Resistance to heat, fire and tracking 39 29 Resistance to rusting 41 Appendix A Electronic circuits 42 Appendix B Classification of controls as type 1 or type 2 in accordancewithBS3955 44 Appendix C Measurement of creepage distances and clearances 44 Figu
9、re 1 Standard test finger 10 Figure 2 Special test finger 10 Figure 3 Test pin 11 Figure 4 Load for rotating accessory 12 Figure 5 Diagram for leakage current measurement at operating temperature for class II parts 14 Figure 6 Diagram for leakage current measurement at operating temperature 14 Figur
10、e 7 Diagram for electric strength test at operating temperature 15 Figure 8 Vertical rain apparatus 17 Figure 9 Spray apparatus 18 Figure 10 Splash apparatus 18 Figure 11 Device for testing shoulders in conduit entries 23BS7462:1991 ii BSI 02-2000 Page Figure 12 Schematic representation of cord anch
11、orages 31 Figure 13 Typical examples of pillar, screw and stud terminals 34 Figure 14 Ball-pressure apparatus 39 Figure 15 Hot mandrel apparatus 40 Figure 16 Arrangement and dimensions of electrodes for tracking test 41 Table 1 Maximum temperature rises 7 Table 2 Test voltages for electric strength
12、test 20 Table 3 Limiting temperatures of windings 21 Table 4 Maximum temperature rises during motor tests 21 Table 5 Test force for screwed glands 22 Table 6 Size of cable and conduit entries 28 Table 7 Dimensions of pillar terminals 32 Table 8 Dimensions of screw terminals 33 Table 9 Dimensions of
13、stud terminals 33 Table 10 Torque values for screws and nuts 36 Table 11 Creepage distances and clearances 38 Table 12 Creepage distances and clearances for electronic circuits 44 Publication(s) referred to Inside back coverBS7462:1991 BSI 02-2000 iii Foreword This British Standard has been prepared
14、 under the direction of the Gas Standards Policy Committee. Its primary purpose is to supplement standards for the safety of domestic gas appliances, e.g. BS 5258, which, while purporting to cover electrical as well as gas and mechanical safety aspects, do so only by general reference to BS 3456-101
15、. This British Standard is intended for appliances of gas heat input not exceeding60kW and in which there is no intentional additional electrical heating. It is based on, and the format closely follows that of, BS 3456-101 which itself is the implementation in a British Standard of CENELEC 1)Harmoni
16、zation Document 251 S3. Attention is drawn to the requirements of the Low Voltage Electrical Equipment (Safety) Regulations 1989. 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. Compl
17、iance 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, pages1to 46, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have
18、had amendments incorporated. This will be indicated in the amendment table on the inside front cover. 1) European Committee for Electrotechnical Standardization.iv blankBS7462:1991 BSI 02-2000 1 1 Scope This British Standard specifies the electrical safety requirements for domestic gas appliances, h
19、ereinafter referred to as appliances, operating from a240V50Hz single phase supply without electrical heating and with a maximum electrical input of1kW and a maximum gas heat input of60kW. In this standard, references to “hazards” denote those hazards arising from the electrical equipment and wiring
20、. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this British Standard the following definitions apply. NOTEUnless otherwise specified, voltages and currents are expressed by their r.m.s. values. 2.1 accessible p
21、art or accessible surface a part or surface that can be touched by means of the test finger shown in Figure 1 2.2 all-pole disconnection disconnection of both supply conductors by a single switching action NOTEThe protective (earthing) conductor is not considered to be a supply conductor. 2.3 applia
22、nce for building-in a fixed appliance intended to be installed in a cabinet, in a prepared recess in a wall, or in a similar situation NOTEAppliances for building-in may not have an enclosure on all sides, full protection against electric shock being obtained after installation. 2.4 basic insulation
23、 insulation applied to live parts to provide basic protection against electric shock NOTEBasic insulation does not necessarily include insulation used exclusively for functional purposes. 2.5 body includes all accessible metal parts, shafts of handles, knobs, grips, etc. and metal foil in contact wi
24、th all accessible surfaces of insulating material but excluding inaccessible metal parts 2.6 class 1 appliance an appliance in which protection against electric shock does not rely on basic insulation only, but which includes an additional safety precaution in such a way that means are provided for
25、the connection of accessible conductive parts to the protective (earthing) conductor in the fixed wiring of the installation so that accessible conductive parts cannot become live in the event of a failure of the basic insulation NOTE 1Class 1 appliances may have parts with double insulation or rein
26、forced insulation, or parts operating at safety extra-low voltage (see 2.29). NOTE 2For appliances intended for use with a flexible cord or cable, this provision includes a protective (earthing) conductor as part of the flexible cord or cable. 2.7 class II part a part for which protection against el
27、ectric shock does not rely on basic insulation only, but which has additional safety precautions, such as double insulation or reinforced insulation between live parts and accessible metal parts, there being no provision for protective earthing 2.8 class III part a part in which protection against e
28、lectric shock relies on supply at safety extra-low voltage and in which voltages higher than this, excluding spark ignition, are not generated 2.9 clearance the shortest distance between two conductive parts, or between a conductive part and the bounding surface of the appliance, measured through ai
29、r NOTEThe bounding surface of the appliance is the outer surface of the enclosure, considered as though metal foil were pressed into contact with accessible surfaces of insulating material. 2.10 continuous operation operation under normal electrical load and rated heat input for an unlimited period
30、2.11 creepage distance the shortest path between two conductive parts, or between a conductive part and the bounding surface of the appliance, measured along the surface of the insulating material 2.12 detachable flexible cable or cord a flexible cable or cord, for supply or other purposes, intended
31、 to be connected to the appliance by means of a suitable appliance couplerBS7462:1991 2 BSI 02-2000 2.13 detachable part a part that can be removed without the aid of a tool NOTESee 2.36. 2.14 double insulation insulation comprising both basic insulation and supplementary insulation 2.15 extra-low v
32、oltage a voltage supplied from a source within the appliance and, when the appliance is operated at its rated voltage, not exceeding42V between conductors and between conductors and earth, the extra-low voltage circuits being separated from other circuits by basic insulation only 2.16 fixed applianc
33、e an appliance that is fastened to a support or otherwise secured in a specific situation 2.17 hot condition the appliance is operated in accordance with the test methods as specified in the appliance standards for the testing of component temperatures NOTEIn BS 5258, the test methods will be those
34、referred to under the heading “Component temperatures”. In BS 5386-1 they will be found under the heading “Temperature of control handles”, in BS 5386-3 and BS 5386-4 under the heading “Heating” and in BS 5386-5 under the heading “Temperature of components and control knobs”. 2.18 live (part) any pa
35、rt deliberately connected or intended to be connected to one or other pole of the electrical supply 2.19 non-detachable part a part that cannot be removed without the aid of a tool NOTESee 2.36. 2.20 non-self-resetting cut-out a thermal cut-out that requires resetting by hand, or replacement of a pa
36、rt, in order to restore the current 2.21 normal load the load to be applied to an appliance incorporating a motor so that the stress imposed corresponds to that occurring under normal conditions of use 2.22 power supply cord a flexible cable or cord, for supply purposes fixed to, or assembled with,
37、the appliance such that it can easily be replaced, without the aid of special purpose tools, by a similar flexible cable or cord not requiring any special preparation 2.23 rated current the current assigned to the appliance by the manufacturer NOTEIf no current is assigned to the appliance, the rate
38、d current for the purpose of this standard is determined by calculation from the rated input and the rated voltage and/or by measuring the current when the appliance is operating at rated voltage under normal load and at normal operating temperature. 2.24 rated frequency the frequency assigned to th
39、e appliance by the manufacturer 2.25 rated input the electrical input assigned to the appliance by the manufacturer 2.26 rated voltage the voltage assigned to the appliance by the manufacturer 2.27 rated voltage range the voltage range assigned to the appliance by the manufacturer, expressed by its
40、lower and upper limits 2.28 reinforced insulation a single insulation system applied to live parts that provides a degree of protection against electric shock equivalent to double insulation under the conditions specified in this standard NOTEThe term “insulation system” does not imply that the insu
41、lation should be one homogeneous piece. It may comprise several layers that cannot be tested singly as supplementary or basic insulation. 2.29 safety extra-low voltage a nominal voltage not exceeding42V between conductors and between conductors and earth, the no-load voltage not exceeding50V NOTE 1W
42、hen safety extra-low voltage is obtained from the supply mains, it is essential that it be through a safety isolating transformer (see 2.30) or a converter with separate windings. NOTE 2The voltage limits given are based on the assumption that the safety isolating transformer is operated at its rate
43、d supply voltage.BS7462:1991 BSI 02-2000 3 2.30 safety isolating transformer a transformer, the input winding of which is electrically separated from the output windings by an insulation at least equivalent to double insulation, and which is designed to supply a distribution circuit, an appliance or
44、 other equipment at safety extra-low voltage NOTETransformers complying with BS 3535, without provision for earthing and with the appropriate output voltages, are considered to be safety isolating transformers for the purposes of this standard. 2.31 self-resetting thermal cut-out a thermal cut-out t
45、hat automatically restores the current after the relevant part of the appliance has cooled down sufficiently 2.32 stationary appliance either a fixed appliance or an appliance having a mass exceeding18kg and not provided with a carrying handle 2.33 supplementary insulation independent insulation app
46、lied in addition to basic insulation, in order to ensure protection against electric shock in the event of failure of the basic insulation 2.34 thermal cut-out a device which, during abnormal operation, limits the temperature of an appliance, or of parts of it, by automatically opening the circuit o
47、r by reducing the current, and which is so constructed that its setting cannot be altered by the user 2.35 thermostat a temperature-sensing device, the operating temperature of which may be either fixed or adjustable and which, during normal operation, keeps the temperature of an appliance, or parts
48、 of it, between certain limits 2.36 tool a screwdriver, a coin or any other object that may be used to operate a screw or similar fixing means 2.37 type X attachment the method of attachment of a power supply cord NOTESee 2.22. 2.38 working voltage the maximum voltage to which the part under conside
49、ration can be subjected when the appliance is operating at its rated voltage and under normal conditions of use NOTE 1Normal conditions of use include changes of voltage within the appliance imposed by likely occurrences, such as the operation of a circuit-breaker or the failure of a lamp. NOTE 2When deducing the working voltage, the effect of possible transient voltages on the supply mains is ignored. 3 General requirements Appliances shall be so designed and constructed that, in normal use, the electrical function shall be
