Ex'ia' Enclosure With Non-IS Components

This is why it is nonsense:

• A junction box cannot be certified Ex ia; the concept is nonsense as the Ex ia method of protection renders the circuit incapable of causing an incendive spark with two faults applied on the basis of the maximum power dissipation and maximum temperature that can be produced in the hazardous area.
• Terminals are "simple apparatus" under the Ex ia method of explosion protection, as they don't store energy, so it doesn't matter what sort of enclosure the terminals are installed within.
• There is no need to provide Ex-labelled junction boxes in the hazardous area wiring of an Ex ia circuit; bare conductors are permissible in Ex ia circuits in zone 0, for illustration, as it is the barrier protection for the hazardous area equipment and the cable parameters that render the installation safe and not the certificate for any junction box.
• If the Ex ia circuit is supplying equipment located in zone 0 then the presence of an Ex e junction box in the wiring may raise a few eyebrows at inspection time. It isn't wrong, though neither is it necessary as the circuit is Ex ia.
• Nothing has ben mentioned about the cables to be installed downstream of the barrier; these have a greater influence on the safety of the circuit than anything other than the barrier and any Simple Apparatus. Try connecting a barrier to a really long length of MICC cable and creating a test spark at the far end; if the cable is long enough, all that capacitance in it can blow the hazardous area certification literally out of the window!
• The concept of having an Ex ia circuit with non-IS wiring inside an Ex e junction box is nonsense, and if it is being installed into zone 0 then it had better be ripped out again before it is energised.
• If the junction box is being installed in zone 1 or zone 2 then an Ex e box is acceptable provided it is installed correctly, however the circuit no longer needs to be Ex ia if the equipment supplied is in either of those two zones; Ex d equipment could be used instead together with Ex d cable glands installed at the cable entry to the Ex d equipment; Ex d glands are not necessary at Ex e terminal boxes.

This thread, like so many others, highlights the need for sufficient training to have been undertaken before specifying, designing, selecting, installing, testing or modifying hazardous area electrical equipment. So, stop work and ask for training locally. If sutable training were complete, these sorts of questions would never appear in this forum!