Worldwide, explosion protection is essentially based on the international IEC 60079 series of standards, European and American norms, standards, and directives. In the USA, the National Electrical Code (NEC) and in Canada the Canadian Electrical Code (CEC) form the basis.
For the CENELEC countries of the European Community and beyond, Directive 2014/34/EU is of central importance for manufacturers of equipment and protective systems. The worldwide requirements are confirmed by certification according to IECEx. Thus, the application is approved in the type of protection „Increased Safety“ Ex e in Zone 1 and 2.
According to EN IEC 60079-0, Ex terminal blocks are so-called Ex components. By definition, these are components required for the safe operation of devices and protection systems, without fulfilling an autonomous function, however.
They are approved for the type of protection equipment increased safety „e“ and are not marked with the CE mark according to the European ATEX directives 2014/34/ EU.
Notified bodies issue EU type examination certificates in accordance with EN IEC 60079-0; EN IEC 60079-7 and the ATEX Directive. By issuing the Production Quality Assurance Notification, a notified body confirms that the requirements of the ATEX Directive are fulfilled according to Annexes IV and VII.
The accessories you can use is listed in the Ex certificates. To adhere to the creepage and clearance distances for Ex e, use terminations and partition plates. Terminal blocks for intrinsically-safe circuits “i” are passive components.
Therefore, for use in intrinsically-safe circuits, you do not need a type examination certificate. We recommend blue terminals for clear identification and easy recognition. These, as well as the accessories, have to comply with the type according to EN 60079-11.
For applications with type of protection equipment intrinsic safety Ex i, no separate approval is required for terminal blocks. In addition to the Ex e approved terminal blocks, other standard terminal blocks can also be used, whereby the following more stringent spacing requirements apply in the Ex i area:
• Between conductor entries adjacent terminals
• Between conductor entries and grounded metal parts
• Increased requirements for clearances due to solid insulation
When test disconnect terminal blocks or fuse terminal blocks are used, they must have approval for the type of protection for equipment protection increased safety Ex ec. In this case, increased requirements apply to the terminal blocks and their functional units. For example, all disconnectable elements must have a release force greater than 15 N or 100 times their own weight to prevent unintentional opening.
Other national and international approvals and directives are based on the IECEx approval. For example, ATEX for the European market, CCC Ex for the Chinese market, KC for the South Korean market or EAC Ex for the Eurasian Economic Union, which includes Russia, Belarus, Kazakhstan, Kyrgyzstan and Armenia.
The explosion-protected equipment must be marked in such a way that it is used correctly according to its safety-related properties. For terminal blocks of the type of protection increased safety „e“ there is a marking obligation. This marking of the equipment is laid down in IEC/EN 60079 Part 0 and Part 7. The exemplary marking of a terminal block can be seen in the following illustrations.
1. Rated cross-section
2. Rated voltage
3. ATEX label
4. Type of protection label
5. ATEX certificate number
6. IECEx certificate number
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