Detailed in EN 60079‑0 the marking, which is usually in the form of a label, is critical for compliance in every certification regime worldwide. Although there are some local variations, the basic IEC1 markings are fairly universal across all certification systems Worldwide with the exception of the North American certifications (USA and Canada) based on the NEC 500 standard. Even within North America there has been a move towards the IEC system with NEC 505 based on zones rather than the traditional class and divisions. Atex marking contains additional information to that of the UK2, the information here refers to the UK, EU implementation and does not neccessarily cover other certification systems.
As labeling and marking is critical to compliance, equipment labels are designed to make it obvious if they have been altered, defaced, or replaced. As in this example, although the label may have just come loose it is clearly damaged and it is equally possibile it was transferred from another item or taken off to perform un-authorised maintenance. There is no way of determining its validity and would fail any inspection as the motor certification is now invalid.
The requirments for marking are the same irrespective of the apparatus being certifed by an (Atex) Notified Body, Certifying body, or manufacturer. One of the biggest issues of 'self-certifcation' is the incorrect documentation and subsequent marking.
Marking to be on the main part of the equipment and visible on exterior of apparatus when installed. If this is not possible such as on extremely small parts or remote items the marking can be duplicated internally internal as long as it is clearly marked. (See clause 29.11)
The marking shall include:
Combinations of the protection method are allowed where multiple protection methods are used e.g.
Note that for older certification only intrinsic safety will have the EPL 'a', 'b' or 'c' suffix
Where both 'G' & 'D' are on the same line it can be assumed to mean Gas or Dust use Not Gas and Dust unless the certificate states the condition for use in a Hybrid atmosphere. Standard certification for a hybrid (Gas and Dust) atmosphere very rarely exists if at all.
Almost any combination of the following can be used.
Older equipment for used in dust environments has temperature listed as a number rather than the T1 to 6 grouping for gas, it should have units i.e. °C (which are sometimes omitted erroneously) and despite some equipment being available on the market (usually 'self certified' category 3) should never refer to the gas T groupings. Recent versions of En 60079‑0 have clarified the temperature labelling requirements for dust.
For EPL Da a layer depth is required e.g. T200 320°C indicating the maximum surface temperature with a 200mm depth of dust.
Surface temperature without a defined deth of dust is no longer allowed.
(Dust depth of more than 200 mm does not give rise to a further temperature increase that would need to be taken into account)
For EPL Db and Dc If the T rating does not include depth of dust then it is assumed that has been tested without a layer of dust. Otherwise the maximum layer of dust used for test must be included e.g. T20 320°C In addition if the test included for a specified orientation an 'L' subscript must be used e.g. TL 320°C
Such items such as cable gland, blanking glands, adapters etc do not need to be marked with a maximum surface temperature.
If the equipement has multiple temperatures because it has different ambiant ranges conditions or power ratings for example it can be labelled with a range e.g. “T80°C...T195°C” and the certifcate would have an 'X' to indicate special conditions.
The International Electrotechnical Commission is an international body which prepares and prepares and publishes electrotechnology standards, most of the EN 60079 standards are identical to the EIC versions. ↩
Unless of course the UK Government decided to completely mirror the Atex directives ↩
A completely encapsulated device would not have any electrical connections so Ex m is usually used in conjunction with Ex e. The exception being an Ex m component where there could be a flying lead. ↩