1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI British StandardsWB9423_BSI_StandardColCov_noK_AW:BSI FRONT COVERS 5/9/08 12:55 Page 1Electrical earthing Clamps for earthing and bonding SpecificationBS 951:2009BS 951:2009 BRITISH STANDARDPublishin
2、g and copyright informationThe BSI copyright notice displayed in this document indicates when the document was last issued. BSI 2009ISBN 978 0 580 55260 1ICS 21.060.70, 29.120.20The following BSI references relate to the work on this standard: Committee reference GEL/600 Draft for comment 08/3013218
3、1 DCPublication historyFirst published August 1940Second edition February 1948Third edition January 1986Fourth edition November 1999Fifth edition August 2009Amendments issued since publicationDate Text affected BRITISH STANDARD BSI 2009 iBS 951:2009ContentsForeword ii1 Scope 12 Normative references
4、13 Terms and definitions 14 General 25 Construction 26 Material 47 Electrical characteristics 48 Non-slipping torque 59 Marking 5AnnexesAnnex A (normative) Tests for electrical impedance and temperature rise 6Annex B (normative) Short-time withstand current test 8Annex C (normative) Torque test 10Bi
5、bliography 12List of figuresFigure A.1 Test arrangement 7Figure B.1 Test arrangement 9Figure C.1 Apparatus for the torque test 10List of tablesTable 1 Termination reference and conductor size 3Table 2 Maximum torques for screws 3Table A.1 Test currents for temperature rise 7Table B.1 Test currents f
6、or short-time withstand current (based on IEC 60364-5-54:2002, Table A.54.2 with value of k=143) 9Table C.1 Non-slipping torque values 11Summary of pagesThis document comprises a front cover, an inside front cover, pages i to ii, pages 1 to 12, an inside back cover and a back cover.BS 951:2009ii BSI
7、 2009BRITISH STANDARDForewordPublishing informationThis British Standard is published by BSI and came into effect on 31 August 2009. It was prepared by Technical Committee GEL/600, Earthing. A list of organizations represented on this committee can be obtained on request to its secretary. Informatio
8、n about this documentBS 951:2009 supersedes BS 951:1999, which is withdrawn.This revision incorporates more performance-based requirements and new tests for temperature rise and short-circuit.Annex A, Annex B and Annex C are normative.Presentational conventionsThe provisions of this standard are pre
9、sented in roman (i.e. upright) type. Its requirements are expressed in sentences in which the principal auxiliary verb is “shall”.Commentary, explanation and general informative material is presented in notes in smaller italic type, and does not constitute a normative element.Contractual and legal c
10、onsiderationsThis publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.BRITISH STANDARD BSI 2009 1BS 951:20091 ScopeThis British Standard
11、specifies performance and mechanical requirements for clamps used to provide mechanically and electrically sound means of earthing and/or bonding, which are primarily intended for use in electrical installations for the connection of:a) earthing conductors, having a cross-sectional area in the range
12、 2.5 mm2to 70mm2, to earth electrode rods or other means of earthing;b) bonding conductors to metal tubes of circular cross-section that have circumferences of not less than 18.8 mm (i.e. diameters of not less than 6 mm).NOTE 1 These clamps are also suitable for electrically bonding other conductive
13、 parts, where at least one is a tube of circular cross-section. Such clamps are not intended for connection to the armour or sheath of a cable.NOTE 2 Clamps specified in this standard are intended to be used singly.NOTE 3 There is no correlation between the size of the conductor which the clamp cond
14、uctor can accommodate and the size of tube to which it is intended to be fitted.2 Normative referencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the ref
15、erenced document (including any amendments) applies.BS EN 1057, Copper and copper alloys Seamless, round copper tubes for water and gas in sanitary and heating applicationsBS EN 13601, Copper and copper alloys Copper rod, bar and wire for general electrical purposes3 Terms and definitionsFor the pur
16、poses of this British Standard, the following terms and definitions apply.3.1 tubemetal conduit, pipe or rod3.2 terminalconductive part of the conductor clamping unit required for the mechanical clamping and the electrical connection of the conductor(s), including the parts which are necessary to en
17、sure the correct contact pressureBS EN 60999-1:2000, modifiedBS 951:20092 BSI 2009BRITISH STANDARD4 GeneralThe clamp shall comprise:a) a device for making electrical contact with the tube;b) a means of tightening the device on to the tube and maintaining tightness;c) a means of termination separate
18、from the arrangement given in item b) for attaching the protective conductor to the device in item a).The clamp shall be provided with a label or other permanent marking warning against the removal of the clamp, which shall have a means of being securely fixed either to the clamp or the protective c
19、onductor (see 5.5).5 Construction5.1 GeneralThe clamp shall be such that effective electrical and mechanical contact can be made and maintained between the clamp and tubes with diameters within the range for which the clamp is intended.The clamp shall make mechanical contact as specified in Clause 8
20、.The design of the clamp shall be such that its attachment to the tube is not likely to result in the deformation of the latter.5.2 Electrical connectionsElectrical connections, including the connection to the tube, shall be designed in such a way that contact pressure is not transmitted through ins
21、ulating material, other than ceramic, pure mica or other material with relevant characteristics, unless there is sufficient resiliency in the conductive parts to compensate for any possible shrinkage or creep of the insulating material.5.3 TerminalsTerminals shall be such that effective electrical c
22、ontact can be made and maintained between the clamp and an attached protective conductor. The clamp, when installed with the terminal(s) in place, shall be such that it can make electrical contact as specified in Clause 7.The form of construction of the terminal shall ensure that the conductor, soli
23、d or stranded, can be held captive in the clamping unit without deformation of the conductor to an extent which is likely to be detrimental to its strength and energy handling capability.NOTE The terminal may be of a screwed or screwless construction.When a conductor is clamped by the end of a screw
24、 bearing directly upon it, the screw end shall be profiled so as not to damage the conductor. Conformity shall be checked by inspection.A screw terminal shall be capable of accepting one of the following:a) a conductor clamped under a screw head provided with a captive washer so that the screw head
25、does not act directly on the conductor; orBRITISH STANDARD BSI 2009 3BS 951:2009b) a single conductor clamped directly by a screw-threaded arrangement, the cross-sectional area of the conductor being within the range specified in Table 1; orc) a bolted-on cable socket from a range of sockets which c
26、an accommodate conductors having cross-sectional areas covering the whole range specified in Table 1.Clamps having terminals in accordance with a) or b) shall be marked in accordance with 9.1c). It shall be possible to loop in and out of a screw-threaded arrangement with an unbroken conductor.Table
27、1 Termination reference and conductor sizeTermination reference Nominal cross-sectional area of conductormm2A 2.5B 4C 6D 10E 16F 25G 35H 50I 705.4 ScrewsScrews which are used:a) in a screw-threaded arrangement in a termination; orb) for attaching a cable socket to a termination; orc) for tightening
28、the appropriate part of the clamp on to the tubeshall be capable of sustaining, without loss of function, the application of the appropriate torque specified in Table 2.Table 2 Maximum torques for screwsNominal diameter of screwmmTorqueType I screws A)NmType II screws B)NmUp to and including 2.8 0.2
29、 0.4Over 2.8, up to and including 3.0 0.25 0.5Over 3.0, up to and including 3.2 0.3 0.6Over 3.2, up to and including 3.6 0.4 0.8Over 3.6, up to and including 4.1 0.7 1.2Over 4.1, up to and including 4.7 0.8 1.8Over 4.7, up to and including 5.3 0.8 2.0Over 5.3, up to and including 6.0 2.5A)Grub screw
30、s which, when tightened, do not protrude from the hole, and other metal screws which cannot be tightened by a tool wider than the minor diameter of the threaded hole.B)Other metal screws.BS 951:20094 BSI 2009BRITISH STANDARD5.5 Warning provisionA permanent label or marking provided with each clamp s
31、hall be durably marked in a legible type not less than 2.5 mm high with the words “SAFETY ELECTRICAL CONNECTION DO NOT REMOVE” in addition to the information specified in 9.1a) and b) where this information is not given on the clamp.6 MaterialMetal components, including current-carrying parts, shall
32、, according to the intended use (see 9.2), have adequate mechanical strength, resistance to corrosion and, in the case of current-carrying parts, electrical conductivity.Conformity shall be checked by inspection and, if necessary, by chemical analysis.The following metals and coatings can be used in
33、 normal conditions of chemical pollution. Stainless steel containing at least 13% chromium and not more than 0.09% carbon. Phosphor bronze. Alloy of copper with additional protection, e.g. tin or nickel. Steel with a suitable protection, such as: an electroplated coating of zinc according to ISO 208
34、1, the coating having a thickness of at least 20 m; an electroplated coating of nickel and chromium according to BS IS0 1456, the coating having a thickness of at least 20 m; an electroplated coating of tin according to ISO 2093, the coating having a thickness of at least 20 m.Others coatings with a
35、n equivalent degree of protection can be used.No part shall be made of unalloyed copper.All parts of the clamp using material less than 1 mm thick shall be inherently resistant to corrosion, e.g. made of phosphor bronze or stainless steel.7 Electrical characteristics7.1 Electrical impedance testWhen
36、 tested in accordance with Annex A, the impedance between the protective conductor and the tube shall not exceed 0.4 mX. 7.2 Temperature riseWhen tested in accordance with Annex A, the temperature rise measured at the termination of the conductor and the interface of the pipe shall not exceed 52 K.7
37、.3 Short-time withstand current testWhen tested in accordance with Annex B, no damage that might impair further use shall have occurred to any part of the clamp and BRITISH STANDARD BSI 2009 5BS 951:2009the impedance between the protective conductor and the tube shall not exceed 1 mX. 8 Non-slipping
38、 torqueWhen a clamp is tested in accordance with Annex C, any movement between the earth clamp band and the test mandrel shall not exceed (2 null0.5) mm.9 Marking9.1 GeneralThe following information shall be clearly and durably marked, either on the clamp or on the warning label provided with it (se
39、e Clause 4 and 5.5):a) the number and date of this British Standard, i.e. BS 951:2009 1);b) the makers name or trademark; andc) where the clamp has a termination designed to accommodate a range of conductor sizes: 1) the appropriate termination references in accordance with Table 1, with the limits
40、of the range presented in the form “XY”, where X is the termination reference of the smallest acceptable conductor and Y is the termination reference of the largest acceptable conductor; or 2) the range of conductor sizes in mm2, e.g. 2.56.0.9.2 Marking of the packageThe package in which the clamp i
41、s supplied shall be marked with the following information:a) the type of application and environment for which it is intended;b) specific types of tube for which application of the clamp is suitable;c) the diameter or range of diameters for which the clamp is suitable;d) where the clamp has a termin
42、ation designed to accommodate a conductor by a screw-threaded arrangement:1) the appropriate termination references in accordance with Table 1, with the limits of the range presented in the form “XY”, where X is the termination reference of the smallest acceptable conductor and Y is the termination
43、reference of the largest acceptable conductor; or2) the range of conductor sizes in mm2, e.g. 2.56.0;e) a warning, “Not intended for use on the sheath or armour of a cable”.1)Marking BS 951:2009 on or in relation to a product represents a manufacturers declaration of conformity, i.e. a claim by or o
44、n behalf of the manufacturer that the product meets the requirements of the standard. The accuracy of the claim is solely the claimants responsibility. Such a declaration is not to be confused with third-party certification of conformity.BS 951:20096 BSI 2009BRITISH STANDARDAnnex A (normative) Tests
45、 for electrical impedance and temperature riseA.1 ApparatusA.1.1 Tube, of diameter appropriate to the size of clamp to be tested, made from copper rod conforming to BS EN 13601 or from thick walled copper tube conforming to BS EN 1057, with a bright finish produced by the manual application of fine
46、wire-wool, and subsequently degreased.A.1.2 Protective conductor, having a cross-sectional area of 2.5 mm2or a value corresponding to the smallest conductor size the clamp is designed to accept when this exceeds 2.5 mm2.A.1.3 Voltmeter.A.2 ProcedureA.2.1 General arrangementsMount the clamp under tes
47、t upon a length of tube (A.1.1) of a nominal diameter appropriate to the design of clamp, as illustrated in Figure A.1. Where the means of tightening the appropriate part of the clamp onto the tube incorporates a screw thread, apply a torque of the appropriate value specified in Table 2.Attach the p
48、rotective conductor (A.1.2) to the clamp under test (see Figure A.1).A.2.2 Electrical impedanceWhere a clamp is suitable for a range of tube diameters, test the smallest diameter tube in the range.Connect one terminal of the voltmeter (A.1.3) to a point on the protective conductor adjacent to the cl
49、amp termination and the other terminal to a point on the tube adjacent to the clamp, but on that part of the tube not carrying the test current.Pass an alternating current of 25 A, having a no-load voltage not exceeding 12 V, for 1 min, between the protective conductor and the tube.NOTE The means of attaching the conductor completing the circuit to the tube (see Figure A.1) should be such that negligible impedance exists at that point.Measure the potential drop across the interface between the protective conductor
