A Brief History and Explanation of the Atex Guidelines

The Atex Directive has shifted and changed since it first began to be enforced during the summer of 2003. The purpose of the directive was to ensure a consistent approach to the requirements of Atex equipment, both electrical and mechanical, throughout Europe, and to provide an safer environment for employees who were already regularly exposed to dangerous situations. By making the same rules apply across the continent, nations were given a better guarantee toward worker safety.

Over the past ten years technology has shifted significantly, and the directive has worked to keep Atex equipment current with the latest safety features for explosive environments. The rules stated in Atex also apply to nations that sell products within Europe or who conduct work there. The latest update to the Atex Guidelines, the fourth edition, were published on September 2012. As of this publication, the proposed changes are still being reviewed by the European Parliament with an expected determination expected early in 2013.

To better understand Atex equipment and regulations, one should know the specific hazardous conditions defined by the directives.

Atex Definitions

While Atex can be applied to some devices that are used in less hazardous conditions, the directive predominantly covers the requirements of equipment used in potentially explosive environments. The Atex Directive states that all equipment is required to meet the restrictions of the guidelines, including andy machine, part of the controls, or mobile device that is meant to function in an environment where it could serve as a source of ignition or where it is instrumental in ensure safety measures are on place. One of the major changes was to include non-electrical equipment, including devices used outside of the explosive atmosphere that are meant to enhance the functioning of safety or mitigating equipment.


The directive further defines an explosive environment as having a mixture of the following four elements:

There is always oxygen present.
There is a flammable element present, and includes any vapors/gases or dust (only one of these three types must be present to qualify for this condition).
There must be an ignition source (the devices that must follow the directives fall under this condition).
Following ignition, the explosion could spread to all of the remaining source (condition 2). This guideline was added with the 2012 revision still under debate. Previously all three of the previous conditions were required. However, some dusts and other flammable elements do not necessarily burn in their entirety during the combustion.

Atex Criteria

The directive includes the all devices used in potentially explosive environments that meet any one of the following criteria.

• Sources that could cause potential ignition on their own.
• In the event of an explosion, any protective system that is meant to automatically attempt to stop the explosion, or failing that to mitigate the effects of the resulting pressure and fire.
• Any device that is supplementary or enhance the safety provided by devices that are designed for the two previous purposes.
• Any parts, including spare parts, or components that cannot work alone but are required for primary equipment or systems to properly function.

The full Atex Guidelines are available for further review. Special attention should be paid to the “Levels of Protection for various Categories of Equipment” to see where different types of Atex equipment fall in the directive. For instance, if the level of protection is normal, the requirements are far less rigid than for a product meant to meet a Very High level of protection that is part of the M 1 group.