The GMTC Guide to BS EN 50262 and BS 6121 (new edition), Parts 1 and 5
the new standards for Electrical Cable Glands, their accessories and use
The Gland Manufacturers Trade Committee (formerly Technical Committee) was founded in 1975, and represents the cable gland manufacturers within the UK. It is represented on several UK and European standards committees, and collectively ensures the safe design manufacture and installation of cable glands.
Issue
3 dated 10th December 2005.
E&OE. This page and subsidiary pages are for information only.
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Contents:
New Standards for Cable Glands
A new European standard for Cable Glands, EN 50262, was published in September 1998. The new standard is very different from the previous British standards in four important respects.
EN 50262 was published in the UK in March 1999, and the pre-1999 BS 6121 series of British Standards for Mechanical Cable Glands has subsequently been revised or withdrawn because they contain conflicting requirements. Because BS EN 50262 does not cover all the types of cable glands covered by the pre-1999 BS 6121 series, a revised BS 6121 Part 1 has been published, covering only those gland types not covered by BS EN 50262. BS 6121 Part 5 has been extensively revised, providing a code of practice for selection, installation and maintenance of all cable glands.
The New Methodology of The European Standard
It is important to understand the key change in methodology. The pre-2000 BS 6121 was a dimensional standard ensuring a single and relatively high level of performance, expected to cover the vast majority of users’ requirements. The new standards require only that a product meets the minimum requirements for safety. This means that users can no longer simply specify or buy any product, assuming it will meet his needs. The new standards allow the product to be classified as meeting performance levels above the minimum, but the user must be careful to ensure the specification of the cable gland and accessories meets his needs. The most basic products meeting the requirements of EN 50262 will not go anywhere near meeting all users' requirements.The manufacturer must now publish more detailed information about his products. This includes a complete performance classification to help specification and selection and full installation instructions to ensure safety. There is now a greater onus on the user to investigate published information on the product in terms of his own needs. Manufacturer’s will provide much more information than before, but the user must now make more decisions regarding the suitability of the product for the application.
The change in methodology will allow a wider choice of products, some traditional, some innovative, only some of which will be to familiar designs and suitable for normal UK installation practice. Conversely this means that manufacturers can offer products tailor-made for specific applications, provided they meet the mandatory requirements of the new standards.
The new EN standard does not include all products which were included in BS 6121, because the new standard defines a cable gland as having three functions/features: metric threads, cable retention and cable sealing. Products which we would have described as cable glands in the past that do not offer cable sealing are outside of the scope of EN 50262 and so are included in the revision of BS 6121. Cable glands with non-metric entry threads are covered by a UK National Annex to EN 50262.
Cable glands, as electrical products, must comply with the Essential Safety Requirements of the Low Voltage Directive, and so have to be sold CE marked. Under the LVD, unlike products covered by the “new approach” Directives, products made to any EN standard are deemed to meet the Essential Safety Requirements of the Directive, whether or not the standard has been listed in the Official Journal of the EU. The new EN (at amendment level A1) has been listed under the LVD. A user who wants to ensure he meets the requirements of the LVD is advised to always buy from a supplier who both provides the technical (catalogue) information required by the standard and retains the CE Marking technical file required by the Directive. It is important to note that where the product is of non-EU origin the company importing the product into the EU is responsible for applying the CE mark and maintaining the technical file.
The new standards do not require any third party certification. It is sufficient that a manufacturer declares that his products conform. The same declaration will in effect be the manufacturer’s declaration required under the rules for CE Marking.
No new designs tested to the pre-2000 editions of BS 6121 may be launched after 01/03/2001.
Designs tested to BS EN 50262 may be put on the market any time from 01/03/1999.
Designs tested to the revised BS 6121 may be put after 21/02/2005.
According to information received by GMTC, the following applies to industrial glands, i.e. all except those manufactured for use in hazardous areas:-
All industrial glands must be CE marked, but marking may be on packaging.
Products made to the new EN standard, as well as those made to any new BS standards which are not yet (or will not be) published at European level, will meet the requirements of the LVD.
It is not enough for a manufacturer to simply mark products with a C and an E. It is necessary for the manufacturer or importer to maintain a Technical File and to make and publish a Declaration of Conformity. This system is policed by the Trading Standards Office.
For products of non-EU origin, the importer must physically keep the Technical File in the EU country into which the goods are first imported.
According to the Low Voltage Directive (73/72/EC) most low voltage electrical equipment must meet certain essential safety requirements before it can be sold in EU member states. All such equipment (except items which are purely components) must also be CE marked in accordance with Directive 93/68/EEC. To bear the CE mark, equipment must meet the essential safety requirements of the Directive, and the manufacturer or importer must maintain a file in which he keeps (amongst other information) details of how he can demonstrate that the products meet these requirements.
It is possible to meet the requirements by ensuring and demonstrating that the equipment is designed and constructed in accordance with those requirements. However it is easier if the product is “presumed to comply”. Such a presumption is made if the products are manufactured in accordance with harmonised European standard documents (of types EN or HD), or IEC standards (where no EN/HD exists) or National standards (where not yet published at European level).
At one time the definition of a “harmonised” standard in the context of the LVD was not the same as in the case of other “New Approach” Directives, where “harmonisation” is concluded only once the EN standard is listed in the Official Journal of the EU as offering a presumption of conformity with a particular Directive. In the case of the LVD, the EN standard became “harmonised” on publication at national level. This now appears to have changed so that the LVD works like other directives. There is now a nationally published European (EN) standard for cable glands (BS EN 50262:1999) which covers all cable glands which feature cable retention, cable sealing and metric threads.
The EU issues a Guide to the LVD and in this guide states quite clearly that cable management systems are included in the scope of the Directive as equipment. Coupled with advice received from both BEAMA and the DTI, the GMTC has for a long time adopted the policy that cable glands are both completely within the scope of the Directive and must be CE marked. The hierarchy of methods GMTC members adopt to meet the essential safety requirements of the Directive is therefore:
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Glands with sealing and metric entry threads |
Presumed to meet requirements where they are manufactured in accordance with BS EN 50262:1999. |
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Glands with sealing and non-metric entry threads |
Compliance with requirements via testing in accordance with BS EN 50262:1999 and its UK National Annex. |
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Glands with no sealing |
These products (formerly known as BW cable glands) are now referred to as armour glands, and compliance with requirements is demonstrated by testing in accordance with the new edition of BS 6121 Part 1 (there is not an EN standard for these products). |
New and Old Standards
In one important respect the old and new standards are the same: Neither of them require third party certification. In both cases it is enough that the manufacturer certifies or declares that his products conform. In nearly every other way, the philosophy of the new standards differs from the old ones, as follows:
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New Standards |
Pre-2000 BS 6121 Standards |
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Are performance and safety standards. The EN plus amendment A1 is currently harmonised under the Low Voltage Directive. (A1 is mandatory for compliance after 1/4/2003).
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Was a construction and type test compliance standard. |
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Are written primarily for test house use, except for BS 6121 Part 5, so users need only buy the new revision of BS 6121, Part 5.
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Was written in such a way as to be readily understandable by specifiers as well testers. |
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Are generally entitled "Cable Glands for Electrical Installations".
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Were generally entitled "Mechanical Cable Glands". |
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Do not specify any named types of cable glands. |
Specified distinct types of product (e.g. BW, CW, E1W etc).
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Are not prescriptive about design (they are not blue-prints).
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Specified dimensional properties (they were blue-prints). |
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Require classifications by manufacturer (some being mandatory and some optional). Some classifications have defined sub-categories to represent levels of performance, whilst some simply specify a minimum and leave the manufacturer to declare a higher performance.
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Required simply that the products met the tests specified in the standard. |
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Do not mention different types of cable, except that some tests refer loosely to "armoured" cable.
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Specified gland types for use with various particular types of cable. |
The structure of the new standards differs from the old ones, as follows:
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New Standards |
Pre-2000 BS 6121 Standards |
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The European standard (EN) only covers cable glands with metric threads and sealing. |
There was no European standard. |
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A National Annex to EN 50262 deals with testing glands with non-metric threads. The revision to BS 6121 will cover products outside the scope of the EN:
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The old BS standard comprised four parts as follows:
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The various parts of the new BS standard are no longer about different materials. Cable glands of any material are covered either by the EN or the new BS standard. |
The various parts of the old BS standard concerned different materials. Requirements were different according to material. |
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BS 6121 Part 1 refers to tests specified in EN 50262. |
Each part of the standards had its own test requirements. |
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The EN cross-refers only to IEC and EN standards, whilst the BS standard will refer to certain HD and BS documents. BS 6121 Part 5 refers to the IEE Wiring Regulations. |
The standards referred to various BS documents. |
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The new standards (except BS 6121, Part 5) are based on the following structure:
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The old standards were based on the following structure (using Part 1 as the example):
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Table 1 lists the actual test requirements of the new EN, compared to those of BS 6121, Part 1 (metal glands).
Table 2 shows the classifications available to manufacturers under the new standards.
Table 3 cross-refers to some common BS6121 glands, showing what a user should look for if he is used to ordering a particular BS 6121 gland type.
Information which must be supplied by the manufacturer or user includes:
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New Standards |
Pre-2000 BS 6121 Standards |
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On the Product:
In the Literature:
From user with order:
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On the Product:
In the Literature:
From user with order:
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The new standards state that cable glands should comply with EN 50262 (and/or BS 6121 as revised) and that there may be other/different requirements for glands for use in hazardous areas. This clause is open to interpretation, and it may be that some hazardous area products are tested only to the hazardous area standards.
There is no relationship between the bodies who write the industrial standards and the hazardous area ones, so it is not to be expected that there will be any commonality between the requirements. (There is certainly none now).
The rules about using cable entries in EExi or ExN equipment are specified in the hazardous area standards, and it may be the case that industrial glands made to non-hazardous area standards will suffice.
Be aware that some two-part grommets might need to meet these requirements.
Sealing arrangements which are integral to the equipment, such as a male bush with a sealing ring may be deemed to be a cable gland and therefore must meet these requirements.
The information in this document is intended to be used as a guide only. It is intended to help GMTC members’ clients. For detailed information and advice, you should refer to the relevant published standards.
Nothing in this document should be taken as conflicting with the requirements of BS 6121, Part 5:2005.
Any errors or omissions should be reported to:
GMTC
Secretariat
c/o 1 Ambarrow Crescent
SANDHURST
GU47 8JA
Fax:
01252 878883
e-mail:
secretary@gmtc.org.uk
© GMTC 2003
Last updated 02/06/03