Due to the national differences inherent within the ANSI, UL, ISA and CSA standards, as well as those contained in the prevailing wiring rules, it is not sufficient for equipment intended for use in hazardous locations to be certified solely for IECEx applications.
It must also be certified and marked with an AEx or Ex codification, signifying that it has been locally assessed, tested and certified to all of the relevant ANSI, UL, ISA or CSA standards. The equipment must then be installed in accordance with the API, NEC or CEC wiring practices respectively.
For example, a cable gland that is only IECEx certified for Class I Zone 1 Ex d IIC, must not be used in Class I Zone 1 AEx d IIC equipment or Class I Division 1 equipment.
Cable glands, and also equipment, should have suitable local certification and would typically be marked like these examples:
AEx db IIC
AEx d IIC Gb
The above rationale would not be limited only to cable glands, and would extend to other electrical equipment. Should there be applicable local standards they too would need to be assessed, tested and certified to ensure that they meet the required conditions before they can be considered for use in hazardous locations in these jurisdictions.