Flame Proof Box

How does one operate the breaker without opening the box and exposing live terminals in Zone 2 before operating it <rhetorical question>?

It's not practicable. Select a different solution.

• Here's one: position the circuit breaker outside the hazardous area and control the breaker from an EEx ib (minimum, though EEx ia is better) circuit connected to a pressure sensor inside the enclosure. The power sould not be applied to the 100A load until both the pressure in the box is higher than in the Zone 2 and a minimum number of air changes have taken place to purge any flammables out of the pressurised enclosure, which can be done using a timer outside the hazardous area. The installation is then EEx p.

I am using circuit breaker with door interlocking kit, and a 100A contactor inside this flame proof box. Rest of my electrical equipments are inside a purge panel. I will mount this flame proof box to the right hand side of purge panel. Any failure in purge (low pressure) should trip the main contactor insde the flame proof box. what am confusing is the heat released by this contactor during ON/OFF will cause any problem?

NEMA 4 materials are made for these areas. Seek professional electrical engineer to help with your project.

I for one, would never offer an answer to any problem concerning Ex equipment without seeing it first.

There's only so much information that can be given in a forum of this nature to ensure the respondent isn't left open to litigation.