arpadveress 
…on the other side a good example of iec 60079-26:
Examples of combinations of two independent Types of Protection (min Gb it shall be) are as follows (than it can go as Ga):
– inductive transmitters (for example proximity switches, electrical position sensors) with intrinsic safety “ib” enclosed by encapsulation “mb”. The connections to intrinsically safe “ib” circuits can be protected by the increased safety “e”;
– a luminaire designed as increased safety “e” may be included in a flameproof enclosure “d”;
– measuring transducers with intrinsic safety “ib” and a flameproof enclosure “d”;
– equipment with electrical circuits of intrinsic safety “ib”, additionally protected by powder
filling “q”;
– electromagnetic valves with encapsulation “mb”, enclosed by a flameproof enclosure “d”;
– increased safety “e”, with pressurized equipment “pxb”.
And NOT as one described earlier at Linkedin: in an Ex d box there are Ex e terminals, so it immediately becomes Ga.
Ex personnel competency matters!
Keep up good work!
Arpad
