Agree with Tony, This is the whole point of sealed conduit systems in hazardous areas. As for the wiring system, in the NEC normally calls for 105C to 125C insulation types.
Even the the panels and boxes related to class 1 division 1 are designed to give a controlled release of pressure within the containment installation. Which is why they are so dammed heavy, with large area flat sealing faces, they have to be able to contain initial internal explosions, while the sealing flat faces, expand enough to allow the escape of pressure.
One of the most important aspects of these conduit systems is the placement of sealing fittings and knowing Where to fit them. That significantly reduces the risk of flame paths from one area to another. It's similar to compartmentalising the conduit system into sections, thus confining/restricting any faults in the system to the area they originate in.