In Europe, the process of harmonization of regulations has opened a new phase in technological development and, to all intents and purposes, can be considered a success of the process of integration of the European Union. The birth of the EEC, the establishment of the CENELEC and CEN technical committees, the first ATEX 94/9/EC regulation and then the new ATEX 2014/34/EU regulation... let's retrace together the last steps that led to the present day have a harmonized regulatory framework at Eu
by Andrea Battauz, R&D Project Engineer of Cortem Group
In the second half of the 20th century, in many industrial and developing countries, electrical equipment suitable for use in potentially explosive atmospheres was subject to different legislation than that concerning general industrial device. The procedure for placing an industrial device on the market usually consisted of the manufacturer's declaration of conformity to current legislation, which assumed responsibility for it. In the specific case of devices for areas classified as at risk of explosion, administrative bodies were appointed by the government of the States which guaranteed compliance with a standard as a third party with respect to the manufacturer. This approach was present in both Europe and the UK.
The European Economic Community, briefly referred to as the EEC, saw its establishment with the treaties of Rome in 1957 thanks to the founding countries: Italy, France, Belgium, Holland, Luxembourg, and Germany. In the following decades, the six initial members were joined by other nations reaching the current 27 .
The EEC, through the signing of numerous amending treaties, assumed the current structure of the European Union with the Treaty of Lisbon of 2007.
The initial purpose of the European economic community was to eliminate the obstacles to the free exchange of goods between the member countries. In the sector of equipment suitable for use in potentially explosive atmospheres, in addition to duties and other instruments of an economic nature, the diversity of national technical legislations constituted a barrier.
With a view to bringing national standards closer together and then subsequently replacing them with a common scheme, the European bodies indicated for standardization were CENELEC for the electrical part and CEN for the mechanical part. In different countries, the protection methods used and developed starting from mining applications were based on common concepts such as explosion containment (Ex-d), segregation (Ex-p, Ex-o, Ex-q) and energy limitation (Ex-i).
The technical committees CENELEC/TC31 and CEN/TC305 were given the task of examining the differences between national regulations for equipment suitable for use in potentially explosive atmospheres.
Not an easy process given that, even if the basic concepts were the same, the different constructive philosophies were often hidden in the details. As an example, in Germany the entry of the cable into explosion-proof enclosures was via increased safety connection enclosures. In Great Britain the explosion proof system was used while in France special cable entries could be used directly in the explosion proof enclosures.
Equally difficult was finding the common ground in the classification of plant zones, a process that began with the IEC 79-10 published in 1972. In the decade between 1967 and 1977, the European standards for sector equipment saw the light with the publication of the series of standards EN 50014-50019.
Since the end of the seventies, the instrument used for the harmonization of technical regulations has been the use of European directives.
We can divide the implementation of this process into two moments.In an initial twenty-year period, from 1976 to 1997, the directives made explicit reference to the regulations and protection methods that could be used. These included the directives concerning electrical equipment intended for use in places with danger of explosion from code 76/117/EEC to code 97/53/EC. However, it became evident that the legislative instrument of the directive struggled to keep pace with technological development. The latter turned out to be faster than the bureaucratic processes required to issue a directive and its subsequent implementation in the EU states.
The second period of regulatory harmonization began with directive 94/9/EC of March, 23rd 1994 with the specific aim of remedying this problem.
Directive 94/9/EC, in compliance with the so-called "new approach", sanctioned the concept that only the health and safety requirements were listed in the directive, while the technical requirements aimed at guaranteeing the rule of art were referred to the legislation.
The technical evolution could have been better followed by an instrument, that of legislation, characterized by decidedly shorter updating cycles than a directive of a transnational nature.
In the figure, the the Community trademark Ex introduced with directive 76/117/EEC and the CE mark in the new approach.
With the new millennium we have definitively entered the new approach of European directives. On June 30th 2003, Directive 94/9/EC  came into force for equipment, while on July, 1st 2006, directive 1999/92/EC  became mandatory for plants classified as at risk of explosion.
Finally, to get to the present day, the directive with code 2014/34/EU, the new ATEX directive currently in force for equipment, should be mentioned. On the regulatory side, in the early 2000s the series of EN50014…EN50039 standards gave way to the EN60079-… standards of IEC derivation .
Simultaneously with the updating of the equipment to the new regulatory standards, the first part of the acronym of the protection mode changed from EEx - to Ex- on the equipment plates. 
In Europe, the process of harmonisation of regulations has opened a new phase in technological development and, to all intents and purposes, can be considered a success of the process of integration of the European Union.
Following a similar path, the IECEx scheme was born which would like to extend the principle of regulatory harmonisation on a larger scale, involving the whole world.IECEx scheme is accepted only in some countries but it represents an important source of inspiration even where there is a specific national standard.
Notes and bibliographical references:
 the number is updated over the years
 known to most as the ATEX Equipment Directive
 known to most as the ATEX directive on workplaces, in this directive there is the concept of classification in zones of the different areas of the plant
 the latest standards of this series, coded EN 50018, EN 50017 and EN 50015, ceased the presumption of conformity in 2010, see: Official Journal of the European Union C20/16
 EN 50014-1998 27.5 c)