1、BRITISH STANDARD CONFIRMED DECEMBER 1985 BS4678-2: 1973 (Reprinted, incorporating Amendment No.1) Specification for Cable trunking Part 2: Steel underfloor (duct) trunking UDC621.315.671:669.14-461:621.316.17:696.6BS4678-2:1973 This British Standard, having been approved by the Electrical Industry S
2、tandards Committee, was published underthe authorityof the Executive Boardon 15October1973 BSI 04-1999 The following BSI references relate to the work on this standard: Committee reference ELE/80/3 Draft for comment71/29986DC ISBN0580075664 Co-operating organizations The Electrical Industry Standard
3、s Committee under whose supervision this British Standard was prepared consists of representatives from the following Government departments and scientific and industrial organizations: Associated Offices Technical Committee Department of Trade and Industry Association of Consulting Engineers* Elect
4、ric Cable Makers Confederation Association of Manufacturers of Domestic Electrical Contractors Association* Electrical Appliances Electrical Contractors Association of Association of Mining Electrical and Scotland Mechanical Engineers Electrical Research Association Association of Mining Electrical
5、and Electricity Council, the Central Electricity Mechanical Engineers Generating Board and the Area Boards in Association of Supervisory and Executive England and Wales* Engineers* Electronic Engineering Association British Electrical and Allied Manufacturers Engineering Equipment Users Association
6、Association Engineering Equipment Users Association British Electrotechnical Approvals Board for Institution of Electrical Engineers* Household Equipment Institution of Electrical and Electronics British Radio Equipment Manufacturers Technician Engineers Association Lighting Industry Federation Limi
7、ted British Railways Board Ministry of Defence British Steel Corporation National Inspection Council for Electrical Crown Agents for Oversea Governments and Installation Contracting* Administrations Oil Companies Materials Association Department of Employment (HM Factory Post Office* Inspectorate)*
8、South of Scotland Electricity Board Department of the Environment* The Government departments and scientific and industrial 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
9、Standard: Aluminium Federation Electrical Installation Equipment Association of Industrialized Building Manufacturers Association Component Manufacturers Light Metal Founders Association British Electrical Systems Association Ministry of Defence (Army) British Plastics Federation Zinc Development As
10、sociation Confederation of British Industry Amendments issued since publication Amd. No. Date of issue CommentsBS4678-2:1973 BSI 04-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 General requirements 1 4 General conditions for the tests det
11、ailed in Appendix A of BS4678-1 1 5 Classification 1 6 Marking 1 7 Details of construction 1 8 Dimensions 2 9 Resistance to corrosion 2 10 Electrical continuity test 2 Table 1 Sizes and preferred lengths 3 Publications referred to Inside back coverBS4678-2:1973 ii BSI 04-1999 Foreword BS4678-2 has b
12、een prepared at the request of the British Electrical Systems Association. The specification includes overall dimensions and the general construction. The requirements and tests specified in BS4678-1, modified as necessary for underfloor trunking, are applicable to this Part. A British Standard does
13、 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 insid
14、e front cover, pagesi andii, pages1 to 4, 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 theinside front cover.BS4678-2:1973 BSI 04-1999 1 1 Scope This British Stand
15、ard specifies requirements for steel underfloor (duct) trunking, and connectors, intended for the protection of cables in electrical installations which are laid on a structural floor and subsequently covered with a floor screed. The specification includes underfloor (duct) trunking having nominal s
16、izes of 75.0 25.0 millimetres to225.0 37.5millimetres. It does not relate to surface (see BS4678-1), bench, flush floor, overhead lighting or skirting trunking. NOTEThe titles of the British Standards referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of
17、 this British Standard the following definitions shall apply: 2.1 steel underfloor (duct) trunking a fabricated system of metal enclosures assembled by means of connectors, for the protection of cables 2.2 connectors a device for joining together lengths of underfloor (duct) trunking 2.3 base of und
18、erfloor (duct) trunking that part of the trunking which is in contact with the floor slab and is not considered to be load-bearing 2.4 external dimensions the external dimensions of the cable trunking body only, that is the width and depth not including any projections such as couplings, fixings, fl
19、anges, strengthening angles or stirrups, or continuity strips 3 General requirements 3.1 Underfloor (duct) trunking shall be so designed and constructed as to permit the laying of the trunking on a structural floor without the ingress of cement whilst the floor is being screeded. The trunking shall
20、permit the drawing in of cables and give reliable mechanical protection to the cables. 3.2 The underfloor (duct) trunking shall provide adequate electrical continuity when tested as described in Clause10. 3.3 Connectors shall provide adequate mechanical joints to the trunking. One connector shall be
21、 provided per length of trunking. 4 General conditions for the tests detailed in Appendix A of BS4678-1 The conditions given in BS4678-1 shall apply to this specification. 5 Classification The requirements for Classes2 and3 given in BS4678-1 shall apply to this specification. 6 Marking 6.1 The body
22、of each length of trunking shall be clearly and durably marked with the following particulars: 1) The name or identification mark of the manufacturer, or responsible vendor. 2) The number of this British Standard, i.e.BS4678-2. 3) The class of finish. The marking shall be easily legible and durable.
23、 6.2 Compliance with these requirements shall be checked by inspection. Durability of marking shall be tested by the method described in Appendix A of BS4678-1. After the test the marking shall remain legible. NOTE 1Marking may be achieved by, for example, stampings, printed adhesive labels or water
24、slide transfers. NOTE 2Attention is drawn to certification facilities offered by BSI; see the back cover of this standard. 7 Details of construction 7.1 Underfloor (duct) trunking and connectors shall be made from steel to the dimensions given in Table 1 and shall be protected against corrosion in a
25、ccordance with the requirements given in Clause9. 7.2 If screws are used to assemble the underfloor (duct) trunking, they shall not project internally in such a way as to cause damage to cable insulation. Screws shall have ISO metric threads and shall comply with the requirements of BS4183. Screws s
26、hall be of brass or steel, and, if of steel, shall be protected against corrosion by a finish at least equivalent to zinc coating complying with either BS729-2 or BS3382-2. If self-tapping screws are used these shall be of recognized standard thread cutting type complying with BS4174. Electro-brass
27、plated screws shall not be used. 7.3 Where provision is made for partitions or dividers for the segregation of circuits these shall be adequately secured to the main body of the trunking and shall be the full depth to provide support and strength to the top surface of the assembly.BS4678-2:1973 2 BS
28、I 04-1999 7.4 Knockouts intended for the acceptance of conduits, where provided, shall have a diameter equal to the nominal conduit diameter plus0.25millimetres with a tolerance of millimetres. Where knockouts are provided, these shall be tested as described in Appendix A of BS4678-1. After the test
29、 the knockout shall not have moved relative to the fitting. 7.5 If necessary to meet the requirements for electrical continuity in Clause10, bonding links shall be provided and may be of any material which will minimize the possibility of electrolytic corrosion. 8 Dimensions Steel underfloor (duct)
30、 trunking sizes, thicknesses and preferred lengths shall be those given in Table 1. Preferred lengths3metres, minimum2metres, maximum3metres NOTE 1The thickness of the base may be reduced to a minimum of1.0millimetres if desired. NOTE 2Where a body has more than one compartment and is not made up fr
31、om smaller sizes, the nominal thickness of the body is that specified for the largest compartment. Underfloor (duct) trunking to special order having dimensions differing from the above may be deemed to comply with this specification provided it meets all its other requirements. 9 Resistance to corr
32、osion Trunking and connectors shall be adequately protected against corrosion both inside and outside and shall comply with the requirements for resistance to corrosion for Classes2 and3 in BS4678-1. 10 Electrical continuity test Ten manufactured lengths of underfloor (duct) trunking shall be couple
33、d together with connectors, with their continuity devices fitted where appropriate, in the manner of use stated by the manufacturer. These shall be tested for continuity between the ends of the assembly. The resistance so measured shall not exceed0.057 . 0.5 0.00BS4678-2:1973 BSI 04-1999 3 Table 1 S
34、izes and preferred lengths All dimensions are in millimetres External dimensions (excluding flange projections) Number of compartments Nominal thickness of body (see Note 2) Nominal thickness of partitions and connector material compartments width up to and including 100mm over100mm up to and includ
35、ing 150mm Width Depth 754 251.2 One 1.2 1.0 754 37.52 One 1.2 1.0 1005 251.2 One or two 1.2 1.0 1005 37.52 One or two 1.2 1.0 1507.5 251.2 Two or three 1.2 1.6 1.0 1507.5 37.52 Tow or three 1.2 1.6 1.0 1507.5 251.2 One 1.6 1.0 1507.5 37.52 One 1.6 1.0 22511.2251.2 Three 1.2 1.6 1.0 22511.237.52 Thre
36、e 1.2 1.6 1.0 22511.2251.2 Two 1.2 1.6 1.0 22511.237.52 Two 1.2 1.6 1.04 blankBS4678-2:1973 BSI 04-1999 Publications referred to This British Standard makes reference to the following British Standards: BS729, Zinc coatings on iron and steel articles. BS729-2, Sherardized coatings. BS3382, Electropl
37、ated coatings on threaded components. BS3382-2, Zinc on steel components. BS4174, Selftapping screws and metallic drive screws. BS4183, Machine screws and machine screw nuts-metric series. BS4678, Cable trunking. BS4678-1, Steel surface trunking. BSI Certification Trade Mark The Kitemark The British
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