Ex e Terminal Box - Gas group

[Charz]

Why there is no marking of the gas group on an Ex e Terminal box? For example, Zone 1 AEx e II T6 -- In this why no gas group marking such as IIA, IIB, or IIC?

 

[rbalex]

Why there is no marking of the gas group on an Ex e Terminal box? For example, Zone 1 AEx e II T6 -- In this why no gas group marking such as IIA, IIB, or IIC?

It does indirectly; it depends on the strict definition of Increased Safety:

Increased Safety "e." Type of protection applied to electrical equipment that does not produce arcs or sparks in normal service and under specified abnormal conditions, in which additional measures are applied so as to give increased security against the possibility of excessive temperatures and of the occurrence of arcs and sparks.

The simple "II" indicates it is suitable for all subgroups "A", "B", and "C" as well. Under some specific conditions, certain "AEx" protection techniques may add markings for specific gases. [See Section 505.9(B)(2)] This does not apply to Type AEx e. In coordination with the "Temperature Classification" (T6), the terminal box's suitability should be readily determined.

[EDIT ADD] BIG NOTE Even though it is suitable for Zone 1, Type AEx e is NOT suitable for Division 1. [See Section 501.5] I have said before NEC Zone 1 is a glorified Division 2.