Explosion Protection—The "New Approach" in Europe

Bob Cooper

   Since 1976 there has been legislation in Europe governing the testing, certification and approval of electrical equipment for use in potentially explosive atmospheres, but compliance by manufacturers has been entirely voluntary. More recently, in 1996, a new directive went into force, making the testing, certification, and approval of such equipment mandatory. Beginning July 1, 2003, it will be a criminal offense to sell or place unapproved equipment on the market. This New Approach directive is known by the acronym ATEX, from the French phrase atmosphères explosives.

   The ATEX Directive follows the same lines in terms of conformity assessment as a number of other New Approach Directives, but differs from the existing directives that manufacturers throughout the member states in Europe have been following for more than two decades.

   With ATEX we see the introduction of new terminology. It is the aim of this article to explain how ATEX works from a manufacturer's viewpoint, to describe the roles of notified bodies in the conformity assessment procedures, and to give some examples of the new marking that we will start to see on approved equipment.

The "Old" Approach

   Traditionally, manufacturers and notified bodies have followed a voluntary product certification procedure based on the Directives 76/117/EEC of 18 December 1975, 79/196/EEC of 6 February 1979, and 82/130/EEC of 15 February 1982. Directive 76/117/EEC lays down a framework for the voluntary certification of equipment for use in potentially explosive atmospheres and is accordingly known as the Framework Directive. In 1979 the First Specific Directive, 79/196/EEC, went into more detail, listing the harmonized European standards with which equipment must comply before it can be marked in accordance with the directive and sold freely within Europe. Directive 82/130/EEC, the Gassy Mines Directive, specifically addresses equipment that is used in underground parts of mines and is endangered by firedamp (methane).

   These directives have been amended up to six times since 1979 to encompass amendments to European standards and to reflect the current state of the art in the design of explosion-protected electrical equipment. As standards developed, the directives were amended accordingly. This process of amendment resulted in delays of up to five years before a current standard could be used for certification.

   Implementation of these directives in the United Kingdom (UK) is achieved through a statutory instrument known as the Electrical Equipment for Explosive Atmospheres (Certification) Regulations 1990. This instrument embraces the legislative framework around which the voluntary certification scheme works. Similar instruments implementing these directives exist within the other 14 member states of the European Union. The objective has been to ensure that compliant products can pass freely across national boundaries within Europe without being subject to further controls. Although compliance is not mandatory, a product that did not comply with the directives would stand very little chance of being sold within Europe.

Standards under the Old Approach

   The amended directives list the harmonized standards to which equipment must be constructed and subsequently tested and assessed by notified bodies. These are widely known as the 50014 series of standards, which comprises a number of specific standards. The list below is not exhaustive, but it gives the most commonly used standards.

• EN 50014—General requirements
• EN 50015—Oil immersion "o"
• EN 50016—Pressurized apparatus "p"
• EN 50017—Powder filling "q"
• EN 50018—Flameproof "d"
• EN 50019—Increased safety "e"
• EN 50020—Intrinsic safety "i"
• EN 50028—Encapsulation "m"

   All of these standards were first published by the European Committee for Electrotechnical Standardization (CENELEC) in 1977, and have been amended up to five times in some cases. Between 1992 and 1995, when the second editions were published, manufacturers were keen to design and manufacture their equipment so that it complied with these new standards. However, every change to each standard resulted in an amendment to the directive, which in turn required a change in the member states' national legislation. This drawn-out process meant that, while the second edition of the General Requirements Standard was published by CENELEC in 1992 and the Flameproof Standard in 1994, not until February 1998 were manufacturers able to have equipment tested, assessed, and certified against second-edition standards. It is encouraging that the New Approach goes some way in addressing this problem.

Current Compliance Procedures

   Manufacturers have traditionally designed their products in accordance with the 50014 series of standards, then submitted a sample of the equipment together with descriptive documents (such as schematic drawings and circuit diagrams) to a notified body. The notified body conducts tests and assessments on the sample, examines the drawings, and issues a Certificate of Conformity. The manufacturer must then agree to some form of surveillance of manufacture, where the notified body visits the manufacturing site and assesses the manufacturer's capability to consistently manufacture compliant products.

   This surveillance has been a contentious subject throughout Europe for the last few years. While the requirement for surveillance is laid down in the Directive, the individual member states enforce it. The requirements therefore have been interpreted very differently throughout the member states. Even in the UK, the two notified bodies interpret the surveillance criteria very differently. Some member states choose not to carry out any form of surveillance of manufacture at all. This unsatisfactory state of affairs should be solved with the adoption of the New Approach ATEX Directive.

   Once they have undergone surveillance of manufacture, companies with a Certificate of Conformity can apply the appropriate mark of conformity, known as the distinctive community mark (see Figure 1).

   This mark has become well known over the past two decades both inside and outside Europe. Despite faults in the system, it has generally worked well, and the industry has enjoyed an excellent safety record.

The New Approach ATEX Directive

   Directive 94/9/EC of 23 March 1994 entered into force in March 1996 and is implemented in the UK by The Equipment & Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 1996. Known specifically as the ATEX 100A Directive, it was established under Article 100 of the treaty that first established what we now call the European Union (EU). Article 100a deals with placing products on the market, putting them into service within the EU, and the free movement of goods across national boundaries. It is not directly concerned with product safety.

   A proposed second directive, ATEX 118a, is directly related to safety. Article 118a of the treaty specifically addresses the protection of workers in the workplace. In its current form, 118a is complex. When the proposal was last considered, in January 1996, the UK government made a persuasive case against the proposal, stating that the cost to industry and the economy would be between £67 million and £100 million. Other member states share this view. Nonetheless, the proposal is expected to move forward now that the EU presidency has changed from the UK to Austria. Even so, it is unlikely to become legislation for a number of years.

   ATEX 100a is only one of some 20 New Approach directives that together cover a vast array of products, from low voltage equipment to toys. The Toy Safety Directive was one of the first directives to be adopted and employ the now familiar CE marking. We can expect to see many more New Approach directives in the future.

Why a New Approach?

   One of the primary objectives of the Treaty of Rome in 1957 was to facilitate the free movement of goods within what has since become the European Union. The Single European Act of 1987 introduced amendments to the Treaty with the aim of completing a real single European market by 1992. To achieve this goal, a radical change to the methods used to harmonize regulations within the individual member states was necessary.

   Before the adoption of the New Approach in 1985, CENELEC would write the standards, the standards would be implemented into directives, and the directives would be transposed into the laws of the member states. In essence, standards-making bodies were writing the laws in Europe. By contrast, the New Approach harmonizes safety objectives through a set of generally worded essential health and safety requirements (EHSRs), which lay down in broad terms the requirements equipment must meet. These EHSRs are supported by Harmonized Standards, although you will not find a list of them written in the directives.

Harmonized Standards

   When a New Approach directive comes into force, mandates are given to one of the three recognized standards-making bodies, CENELEC, the European Committee for Standardization (CEN), or the European Telecommunications Standards Institute (ETSI). CENELEC deals with electrical equipment and CEN with mechanical equipment. In the case of ATEX, committee TC 305 of CEN is responsible for writing the standards for mechanical equipment. For electrical equipment this responsibility is given to committee TC 31 of CENELEC. The CENELEC committee's job will be relatively easy, as it will simply amend the 50014 series of standards to third editions, which will in turn be adopted as the Harmonized Standards under ATEX.

    CEN has a more difficult task, as it will have to produce new standards for non-electrical equipment covered by ATEX. Since the standards-making process involves industry, manufacturers, users, and regulators, it often takes several years to develop a new standard. Thus a full set of harmonized European standards will probably not be in place when compliance with ATEX becomes mandatory in July 2003.

Requirements of ATEX

   There are two main differences between ATEX and the existing directives. First, ATEX applies not only to electrical but also to mechanical equipment. Second, ATEX introduces CE marking for the first time for this equipment. After July 2003, it will be illegal to sell or place on the market equipment that doesn't carry the CE marking.

   Before ATEX, there were two directives covering the same equipment. One applied to mining equipment, the other to nonmining equipment. These two directives were overseen by different parts of the European Commission, DG III in Brussels and DG V in Luxembourg, and the requirements of the two directives weren't always aligned. Because ATEX covers both types of equipment, it constitutes a fairly complicated set of requirements. To put this in perspective, the EHSRs listed in ATEX number about 40, compared with just three in the Low Voltage Directive.

   Having generally worded requirements means that there is no longer a need for continual amendment of the regulations as standards develop and new protection concepts are invented. The Directive also lays out a set of conformity assessment procedures, most which will be carried out by notified bodies.

The Role of Notified Bodies

   Under the old directives, there were 15 notified bodies in Europe assessing compliance. Under ATEX there are many more—27 in all, at last count. Not all of these notified bodies operate under all the different sets of the requirements of the directive. Some have been set up purely to assess the quality management systems that control the manufacturing process of certified equipment, a trend with a number of other New Approach directives.

   Annex X of the directive lays down what is required in a Declaration of Conformity. EN 45014 also gives some guidance on the preparation of a declaration. It is this declaration that allows the manufacturer to apply the CE mark.

Markings

   Figure 1 represents an example of the minimum marking we can expect to see on equipment that complies with the ATEX Directive. Some is required by the directive itself, some by the constructional standards. Many think there is too much marking and that it is not useful to the installer.

Conclusion

   The basic principles of the New Approach ATEX Directive are similar to those principles embodied in the existing directives. However, the new terminology and the different procedures will take some time to get used to. The major challenge facing notified bodies will be the uniform application of the requirements and the assessment of products without the aid of harmonized standards.

   Having a level playing field in Europe, where all notified bodies interpret the requirements for certification uniformly and unambiguously, is a distant dream. For example, the UK government recently noted a large number of differences between the English, French, and German versions of the directive. In some cases, different terminology is used, resulting in differing interpretations. However, notified bodies, manufacturers, and users are working hard, through their respective groups, committees, and trade associations, to develop this uniform approach.

   Nevertheless, the current set of constructional standards for electrical equipment has been developed over some 20 years and forms a solid base for electrical equipment manufacturers. For the majority of previously certified electrical equipment, compliance with the new directive should be possible after only minor changes.

Bob Cooper is general manager of SIRA Test Certification Ltd. (UK). He can be reached at +44 181 467 2636.

Back to July/August Table of Contents