II (1) G Ex [ia Ga ] IIC (Ga) Associated Apparatus (Barrier) ATEX/ IEC Marking

Hi Could you please explain detail about the Barrier marking.

I am really confusing about the closed brackets(), and Square Brackets[] in the II (1) G Ex [ia Ga ] IIC (Ga) Marking.

Can anyone explain about the marking for Barrier installed in the safe area/ Hazardous area.

I Understand from the marking II (1) G Ex [ia Ga ] IIC (Ga).

II (1) G: Barrier is installed in the Category 1(Zone0) Hazardous area? does it required any enclosure?
 
Top