Electrical earthing

BS 951:1999 pdf free.Electrical earthing- Clamps for earthing and bonding- Specification.
The following normative references contain provisions which, through reference in this text, constitute provisions of this British Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. For undated references, the latest edition of the publication referred to applies.
BS 1433, SpecifieaUon for copper for electrical purposes — Rod and bar.
[IS EN 1057, Capper (I iid rapper alloqs — Seamless, round copper tubes for water and gas in sanitary and healing applications.
3 Definitions
For the purposes of this British Standard, the following (lefInilion apl)hes.
tube
metal conduit, pipe or rod
4 General
4.1 The clamp shall comprise:
a) a device for making electrical contact with the tube;
b) a means of tightening the device on to the tube; c) a means of locking the arrangement given in item b);
d) a termination separate from the arrangement given in iteni h) for attaching the protective conductor to the device given in item a).
4.2 Each clamp shall be provided with a label to warn against its removal. The label shall have a means of being securely fixed to the clamp or protective conductor (see 5.4).
5 Construction
5.1 General
The clamp shall 1w such that effective electrical and mechanical contact can 1w made and nlalntalne(l between it and tubes with diameters within the range for which the clamp is intended.
The clamp shall make mechanical contact as specified in clause 8.
The design of the clamp shall be such that its attachment to the tube does not result in 11w inevitable deformation of the latter.
5.2 Terminations
The ternunation shall be such that effective electrical contact can be made and maintained between the clamp and an attached protective conductor. The clamp with (he lernunation in place shall he such that it can make electrical contact as specified in clause 7.
The form of construction of the tCrn)1!UItI()fl shall ensure that the conductor, solid or stranded, can be held captive in the terminal without deformation of the conductor to an extent which is likely to be detrimental to its strength and energy handling capability.
N( rr: The termination may he of a wrewed or scn’wle,js (‘OflS1flWtiofl.
Where a conductor i.s clamped by the end of a screw bearing directly upon it, the screw end shall be profiled so as not to damage the conductor.
A screw ternunation shall be capable of accepting one of the following:
a) a conductor clamped under a screw head proidcd with a captive washer so that the screw head does not act directly on the conductor, or b) 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; or
c) a bolted-on cable socket, from a range of sockets wiuch can acconunodate conductors having cross-sectional areas covering the whole range specified in Table 1.Clamps having terminations 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.
5.3 Screws
Screws which are used:
a) in a screw-threaded arrangement in a termination; or
b) for attaching a cable socket to a termination; or
c) for tightening the appropriate part of the clamp on to the tube;shall be capable of sustaining, without loss of function, the application of the appropriate torque specified in Table 2.
5.4 Warning label
A permanent label provided with each clamp shall be durably marked in a legible type not less than 3 mm high with the words“SAFETY ELECTRICAL CONNECTION一DO NOT REMOVE” in addition to the information given in 9.1a) and b) where this information is not given on the clamp.
6 Materials
With the exception of the warning label, all
components shall be made of metal. No part shall he nIa(le of femnis metal other than austenitic stainless steel containing at least 18% chromium. No part shall be made of unalloyed copper; alloys of copper shall be given additional protection where necessary, e.g. by electroplating.
N()TE I The nwlal(s) scleoed should he resistant to the levels ol eormsion that are likely to be encountered in service.
All parts of the clamp using material less than 1 mm thick shall be inherently resistant to cornslon, e.g. made of phosphor bronze.
NOTE 2 All parts designed in be tinder stress when istaIIed shoiikl haw adeqtLde strength to withstand this stTeS5.
Materials shall have a mmuiimin tensile strength of 38i N/nun2.
7 Electrical impedance
When tested in accordance with the method described in annex A, the impedance between the
protective conductor and the tithe shall not exceed 0.1 mft Where a clamp is suitable for a range of tube (lianieters, the smallest diameter tulw in the range shall be used for the test
8 Non-slipping torque
When a clamp is fitted to an appropriate diameter mandrel, and a torque having the value specified in Table 3 is applied in acconlance with annex B, any movement between the earth clamp band and the test mandrel shall not exceed (2 ± 0.5) mm.
If the clamp is suitable for a range of tube diameters, separate torque tests shall be performed using test mandreLs with (liameters equal to the minintuin and maximum nominal tube diameters for which the clamp is designed. A new sample shall be used for each test.
9 Marking
9.1 General
The following information shall be clearly and durably marked either on the clamp, or on the warning label provided with it (see 5.4):
a) the number and date of this British Standard,ie. BS 951:1999);
b) the maker’s name or trade mark;
c) where the clamp has a termination designed to accommodate a conductor directly by a screw-threaded arrangement, the appropriate termination references in accordance with Table 1. The limits of the range shall be presented in the form“X- -Y”, where X is the trmination reference of the smallest acceptable conductor and Y is the termination reference of the largest acceptable conductor.
9.2 Marking of the package
The package in which the clamp is supplied shall be marked with the following information:
a) specific types of tube for which application of the clamp is not suitable;
b) the diameter or range of diameters for which the clamp is suitable;
c) where the clamp has a termination designed to accommodate a conductor by a screw-threaded arrangement, the appropriate termination references in accordance with Table 1. The limits of the range shall be presented in the form“X-Y”, where X is the termination reference of the smallest acceptable conductor and Y is the termination reference of the largest acceptable conductor,
d) a warning“Not intended for use on the sheath or armour of a cable”.BS 951 pdf free download.Electrical earthing