Along with rigid metal conduit there are a number of cable types which are approved for use in these hazardous locations.
Cable used in explosion proof wiring.
Tmc2x cable connector for armoured cables 0 50 hub size aluminum 0 69 0 99 csa.
Explosion proof seals 0 fiber optic seals 1 hermetic wire feedthrough 1 high current feedthrough 0 non hermetic seals 0 stock items 15 terminal seals 0 thermocouple vacuum feedthrough 0 vacuum cable feedthrough 0 wire cable seals 3.
In europe and elsewhere suitably rated cable is connected directly to the equipment using certified flame proof cable glands.
In north america metal conduit must be used for field wiring.
Ex ia ex ib intrinsically safe cable glands designed in such a way that the energy of any spark is lower than that can ignite a flammable mixture.
If heat or sparks from faulty equipment within the enclosure ignite flammable gas present with it the resulting explosion is contained within the enclosure.
Imposes strict requirements for wiring methods in these locations.
Flameproof explosion proof protection methods.
So cable glands and seals may need to be considered but they are of lighter construction as they are not required to cool exploding gases only to prevent the flow of gases.
As you might suspect explosion proof wiring is typically much more expensive than intrinsically safe wiring.