Would like to know the definitions of the following.
EExed and EExde.

I have EExde on a push button by Stahl and thought EExde WAS A d enclosure with E internals but this enclosure is polycarbonate. can you explain?

 

The use of EEx de simply means that the equipment uses both Ex d and Ex e methods of protection - the actual details can vary widely. Sometimes the order of letters can indicate which is the main method of protection, but not always.

In the case of a push-button the usual arrangement is that the switch housing, terminals and internal wiring meet Ex e requirements. The actual switching element however is a potential source of sparks and cannot be dealt with using Ex e. To make the overall assembly safe, the contact elements are enclosed in an assembly which meets Ex d requirements.

 

Hi,

this is so called Hybrid method of protection but some cases quite difficult to identify which one is main part and other one is auxiliary part. For your case, In my point of view the enclosure is Exd certified without depend on type of material made from. Do not think that when enclosure is certified Exd, it must be made of metal.
Should be notice that Ex ed is same Ex de. Other device may be combine types of protection. For example Ex edq; Ex emib...

Hope it clear to you