Increased safety Ex e requires a high integrity of components, removing the ignition the ignition source, i.e. no potential sparking components. The internal temperature of the components is critical (which is different from Ex d where it was the external enclosure temperature which was assessed).
The main features are:
Generally an Ex e assembly is used for just for terminals i.e. Junction boxes.
There are two protection levels Ex eb and Ex ec for Zones 1 and 2 respectively, older equipment will just be labelled Ex e covering both Ex eb and Ex ec.
|Category||Zone of use|
|Ex ec||3||Zone 2||See Ex nA|
|Ex eb||2||Zone 1||Conventional Ex e|
The only real use for the older Ex e and Ex eb assemblies is junction or terminal boxes, although historically other components have had Ex e certification these have largely disappeared from the market leaving just terminals.
However, Ex e is often used in conjunction with another protection technique such as Ex de and Ex em encapsulation which enables additional components to be used inside an Ex e enclosure
This does allow a lot more flexibility than Ex eb, as it allows Ex nA and Ex ec internal components for a built solution using components other than terminals. The intention is it will completely replace the Ex nA protection method but not for some time yet.
Although older equipment has Ex e certification for dust, usually where the ambiguous 'GD' was often used. Modern certifications use Ex t as the easier protection method for dust.