All equipment certified for use in hazardous areas must be labelled to show the type and level of protection applied.
In Europe the label must show the CE mark and the code number of the certifying body (Notified Body). The CE marking is complemented with the Ex mark, followed by the indication of the Group, Category and, if group II equipment, the indication relating to gases (G) or dust (D). For example: Ex II 1 G (Explosion protected, Group 2, Category 1, Gas) Specific type or types of protection being used will be marked.
• Ex ia IIC T4. (Type ia, Group 2C gases, Temperature class 4).
• Ex nA II T3 X (Type n, non-sparking, Group 2 gases, Temperature class 3, special conditions apply).
Industrial electrical equipment for hazardous area has to conform to appropriate parts of standard EN 60079 and in some cases, certified as meeting that standard. Independent test houses (known as Notified Bodies) are established in most European countries, and a certificate from any of these will be accepted across the EU. In the United Kingdom, the DTI appoint and maintain a list of Notified Bodies within the UK, of which Sira and Baseefa are the most well known.
In North America the suitability of equipment for the specific hazardous area must be tested by a Nationally Recognized Testing Laboratory. Such institutes are UL, MET,FM, CSA or Intertek (ETL), for example.
The label will always list the Class(es), Division(s) and may list the Group(s) and temperature Code. Directly adjacent on the label one will find the mark of the listing agency.
Some manufacturers claim "suitability" or "built-to" hazardous areas in their technical literature, but in effect lack the testing agency's certification and thus unacceptable for the AHJ (Authority Having Jurisdiction) to permit operation of the electrical installation/system.
All equipment in Division 1 areas must have an approval label, but certain materials, such as rigid metallic conduit, does not have a specific label indicating the Cl./Div.1 suitability and their listing as approved method of installation in the NEC serves as the permission. Some equipment in Division 2 areas do not require a specific label, such as standard 3 phase induction motors that do not contain normally arcing components.
Also included in the marking are the manufacturers name or trademark and address, the apparatus type, name and serial number, year of manufacture and any special conditions of use. The NEMA enclosure rating or IP code may also be indicated, but it is usually independent of the Classified Area suitability.